Theory Affine_Arithmetic.Affine_Form

section ‹Affine Form›
theory Affine_Form
imports
  "HOL-Analysis.Multivariate_Analysis"
  "HOL-Combinatorics.List_Permutation"
  Affine_Arithmetic_Auxiliarities
  Executable_Euclidean_Space
begin

subsection ‹Auxiliary developments›

lemma sum_list_mono:
  fixes xs ys::"'a::ordered_ab_group_add list"
  shows
    "length xs = length ys ⟹ (⋀x y. (x, y) ∈ set (zip xs ys) ⟹ x ≤ y) ⟹
      sum_list xs ≤ sum_list ys"
  by (induct xs ys rule: list_induct2) (auto simp: algebra_simps intro: add_mono)

lemma
  fixes xs::"'a::ordered_comm_monoid_add list"
  shows sum_list_nonneg: "(⋀x. x ∈ set xs ⟹ x ≥ 0) ⟹ sum_list xs ≥ 0"
  by (induct xs) (auto intro!: add_nonneg_nonneg)

lemma map_filter:
  "map f (filter (λx. P (f x)) xs) = filter P (map f xs)"
  by (induct xs) simp_all

lemma
  map_of_zip_upto2_length_eq_nth:
  assumes "distinct B"
  assumes "i < length B"
  shows "(map_of (zip B [0..<length B]) (B ! i)) = Some i"
proof -
  have "length [0..<length B] = length B"
    by simp
  from map_of_zip_is_Some[OF this, of i] assms
  have "map_of (zip B [0..<length B]) (B ! i) = Some i"
    using assms by (auto simp: in_set_zip)
  thus ?thesis by simp
qed

lemma distinct_map_fst_snd_eqD:
  "distinct (map fst xs) ⟹ (i, a) ∈ set xs ⟹ (i, b) ∈ set xs ⟹ a = b"
  by (metis (lifting) map_of_is_SomeI option.inject)

lemma length_filter_snd_zip:
  "length ys = length xs ⟹ length (filter (p ∘ snd) (zip ys xs)) = length (filter p xs)"
  by (induct ys xs rule: list_induct2) (auto )

lemma filter_snd_nth:
  "length ys = length xs ⟹ n < length (filter p xs) ⟹
    snd (filter (p ∘ snd) (zip ys xs) ! n) = filter p xs ! n"
  by (induct ys xs arbitrary: n rule: list_induct2) (auto simp: o_def nth_Cons split: nat.split)

lemma distinct_map_snd_fst_eqD:
  "distinct (map snd xs) ⟹ (i, a) ∈ set xs ⟹ (j, a) ∈ set xs ⟹ i = j"
  by (metis Pair_inject inj_on_contraD snd_conv distinct_map)

lemma map_of_mapk_inj_on_SomeI:
  "inj_on f (fst ` (set t)) ⟹ map_of t k = Some x ⟹
    map_of (map (case_prod (λk. Pair (f k))) t) (f k) = Some x"
  by (induct t) (auto simp add: inj_on_def dest!: map_of_SomeD split: if_split_asm)

lemma map_abs_nonneg[simp]:
  fixes xs::"'a::ordered_ab_group_add_abs list"
  shows "list_all (λx. x ≥ 0) xs ⟹ map abs xs = xs"
  by (induct xs) auto

lemma the_inv_into_image_eq: "inj_on f A ⟹ Y ⊆ f ` A ⟹ the_inv_into A f ` Y = f -` Y ∩ A"
  using f_the_inv_into_f the_inv_into_f_f[where f = f and A = A]
  by force

lemma image_fst_zip: "length ys = length xs ⟹ fst ` set (zip ys xs) = set ys"
  by (metis dom_map_of_conv_image_fst dom_map_of_zip)

lemma inj_on_fst_set_zip_distinct[simp]:
  "distinct xs ⟹ length xs = length ys ⟹ inj_on fst (set (zip xs ys))"
  by (force simp add: in_set_zip distinct_conv_nth intro!: inj_onI)

lemma mem_greaterThanLessThan_absI:
  fixes x::real
  assumes "abs x < 1"
  shows "x ∈ {-1 <..< 1}"
  using assms by (auto simp: abs_real_def split: if_split_asm)

lemma minus_one_less_divideI: "b > 0 ⟹ -b < a ⟹ -1 < a / (b::real)"
  by (auto simp: field_simps)

lemma divide_less_oneI: "b > 0 ⟹ b > a ⟹ a / (b::real) < 1"
  by (auto simp: field_simps)

lemma closed_segment_real:
  fixes a b::real
  shows "closed_segment a b = (if a ≤ b then {a .. b} else {b .. a})" (is "_ = ?if")
proof safe
  fix x assume "x ∈ closed_segment a b"
  from segment_bound[OF this]
  show "x ∈ ?if" by (auto simp: abs_real_def split: if_split_asm)
next
  fix x
  assume "x ∈ ?if"
  thus "x ∈ closed_segment a b"
    by (auto simp: closed_segment_def intro!: exI[where x="(x - a)/(b - a)"]
      simp: divide_simps algebra_simps)
qed


subsection ‹Partial Deviations›

typedef (overloaded) 'a pdevs = "{x::nat ⇒ 'a::zero. finite {i. x i ≠ 0}}"
  ― ‹TODO: unify with polynomials›
  morphisms pdevs_apply Abs_pdev
  by (auto intro!: exI[where x="λx. 0"])

setup_lifting type_definition_pdevs

lemma pdevs_eqI: "(⋀i. pdevs_apply x i = pdevs_apply y i) ⟹ x = y"
  by transfer auto

definition pdevs_val :: "(nat ⇒ real) ⇒ 'a::real_normed_vector pdevs ⇒ 'a"
  where "pdevs_val e x = (∑i. e i *⇩R pdevs_apply x i)"

definition valuate:: "((nat ⇒ real) ⇒ 'a) ⇒ 'a set"
  where "valuate x = x ` (UNIV → {-1 .. 1})"

lemma valuate_ex: "x ∈ valuate f ⟷ (∃e. (∀i. e i ∈ {-1 .. 1}) ∧ x = f e)"
  unfolding valuate_def
  by (auto simp add: valuate_def Pi_iff) blast

instantiation pdevs :: (equal) equal
begin

definition equal_pdevs::"'a pdevs ⇒ 'a pdevs ⇒ bool"
  where "equal_pdevs a b ⟷ a = b"

instance proof qed (simp add: equal_pdevs_def)
end


subsection ‹Affine Forms›

text ‹The data structure of affine forms represents particular sets, zonotopes›

type_synonym 'a aform = "'a × 'a pdevs"


subsection ‹Evaluation, Range, Joint Range›

definition aform_val :: "(nat ⇒ real) ⇒ 'a::real_normed_vector aform ⇒ 'a"
  where "aform_val e X = fst X + pdevs_val e (snd X)"

definition Affine ::
    "'a::real_normed_vector aform ⇒ 'a set"
  where "Affine X = valuate (λe. aform_val e X)"

definition Joints ::
    "'a::real_normed_vector aform list ⇒ 'a list set"
  where "Joints XS = valuate (λe. map (aform_val e) XS)"

lemma Joints_nthE:
  assumes "zs ∈ Joints ZS"
  obtains e where
    "⋀i. i < length zs ⟹ zs ! i = aform_val e (ZS ! i)"
    "⋀i. e i ∈ {-1..1}"
  using assms
  by atomize_elim (auto simp: Joints_def Pi_iff valuate_ex)

lemma Joints_mapE:
  assumes "ys ∈ Joints YS"
  obtains e where
    "ys = map (λx. aform_val e x) YS"
    "⋀i. e i ∈ {-1 .. 1}"
  using assms
  by (force simp: Joints_def valuate_def)

lemma
  zipped_subset_mapped_Elem:
  assumes "xs = map (aform_val e) XS"
  assumes e: "⋀i. e i ∈ {-1 .. 1}"
  assumes [simp]: "length xs = length XS"
  assumes [simp]: "length ys = length YS"
  assumes "set (zip ys YS) ⊆ set (zip xs XS)"
  shows "ys = map (aform_val e) YS"
proof -
  from assms have ys: "⋀i. i < length xs ⟹ xs ! i = aform_val e (XS ! i)"
    by auto
  from assms have set_eq: "{(ys ! i, YS ! i) |i. i < length ys ∧ i < length YS} ⊆
    {(xs ! i, XS ! i) |i. i < length xs ∧ i < length XS}"
    using assms(2)
    by (auto simp: set_zip)
  hence "∀i<length YS. ∃j<length XS. ys ! i = xs ! j ∧ YS ! i = XS ! j"
    by auto
  then obtain j where j: "⋀i. i < length YS ⟹ ys ! i = xs ! (j i)"
    "⋀i. i < length YS ⟹ YS ! i = XS ! (j i)"
    "⋀i. i < length YS ⟹ j i < length XS"
    by metis
  show ?thesis
    using assms
    by (auto simp: Joints_def j ys intro!: exI[where x=e] nth_equalityI)
qed

lemma Joints_set_zip_subset:
  assumes "xs ∈ Joints XS"
  assumes "length xs = length XS"
  assumes "length ys = length YS"
  assumes "set (zip ys YS) ⊆ set (zip xs XS)"
  shows "ys ∈ Joints YS"
proof -
  from Joints_mapE assms obtain e where
    ys: "xs = map (λx. aform_val e x) XS"
    and e: "⋀i. e i ∈ {-1 .. 1}"
    by blast
  show "ys ∈ Joints YS"
    using e zipped_subset_mapped_Elem[OF ys e assms(2-4)]
    by (auto simp: Joints_def valuate_def intro!: exI[where x=e])
qed

lemma Joints_set_zip:
  assumes "ys ∈ Joints YS"
  assumes "length xs = length XS"
  assumes "length YS = length XS"
  assumes sets_eq: "set (zip xs XS) = set (zip ys YS)"
  shows "xs ∈ Joints XS"
proof -
  from assms have "length ys = length YS"
    by (auto simp: Joints_def valuate_def)
  from assms(1) this assms(2) show ?thesis
    by (rule Joints_set_zip_subset) (simp add: assms)
qed

definition Joints2 ::
    "'a::real_normed_vector aform list ⇒'b::real_normed_vector aform ⇒ ('a list × 'b) set"
  where "Joints2 XS Y = valuate (λe. (map (aform_val e) XS, aform_val e Y))"

lemma Joints2E:
  assumes "zs_y ∈ Joints2 ZS Y"
  obtains e where
    "⋀i. i < length (fst zs_y) ⟹ (fst zs_y) ! i = aform_val e (ZS ! i)"
    "snd (zs_y) = aform_val e Y"
    "⋀i. e i ∈ {-1..1}"
  using assms
  by atomize_elim (auto simp: Joints2_def Pi_iff valuate_ex)

lemma nth_in_AffineI:
  assumes "xs ∈ Joints XS"
  assumes "i < length XS"
  shows "xs ! i ∈ Affine (XS ! i)"
  using assms by (force simp: Affine_def Joints_def valuate_def)

lemma Cons_nth_in_Joints1:
  assumes "xs ∈ Joints XS"
  assumes "i < length XS"
  shows "((xs ! i) # xs) ∈ Joints ((XS ! i) # XS)"
  using assms by (force simp: Joints_def valuate_def)

lemma Cons_nth_in_Joints2:
  assumes "xs ∈ Joints XS"
  assumes "i < length XS"
  assumes "j < length XS"
  shows "((xs ! i) #(xs ! j) # xs) ∈ Joints ((XS ! i)#(XS ! j) # XS)"
  using assms by (force simp: Joints_def valuate_def)

lemma Joints_swap:
  "x#y#xs∈Joints (X#Y#XS) ⟷ y#x#xs ∈ Joints (Y#X#XS)"
  by (force simp: Joints_def valuate_def)

lemma Joints_swap_Cons_append:
  "length xs = length XS ⟹ x#ys@xs∈Joints (X#YS@XS) ⟷ ys@x#xs ∈ Joints (YS@X#XS)"
  by (auto simp: Joints_def valuate_def)

lemma Joints_ConsD:
  "x#xs∈Joints (X#XS) ⟹ xs ∈ Joints XS"
  by (force simp: Joints_def valuate_def)

lemma Joints_appendD1:
  "ys@xs∈Joints (YS@XS) ⟹ length xs = length XS ⟹ xs ∈ Joints XS"
  by (force simp: Joints_def valuate_def)

lemma Joints_appendD2:
  "ys@xs∈Joints (YS@XS) ⟹ length ys = length YS ⟹ ys ∈ Joints YS"
  by (force simp: Joints_def valuate_def)

lemma Joints_imp_length_eq: "xs ∈ Joints XS ⟹ length xs = length XS"
  by (auto simp: Joints_def valuate_def)

lemma Joints_rotate[simp]: "xs@[x] ∈ Joints (XS @[X]) ⟷ x#xs ∈ Joints (X#XS)"
  by (auto simp: Joints_def valuate_def)


subsection ‹Domain›

definition "pdevs_domain x = {i. pdevs_apply x i ≠ 0}"

lemma finite_pdevs_domain[intro, simp]: "finite (pdevs_domain x)"
  unfolding pdevs_domain_def by transfer

lemma in_pdevs_domain[simp]: "i ∈ pdevs_domain x ⟷ pdevs_apply x i ≠ 0"
  by (auto simp: pdevs_domain_def)


subsection ‹Least Fresh Index›

definition degree::"'a::real_vector pdevs ⇒ nat"
  where "degree x = (LEAST i. ∀j≥i. pdevs_apply x j = 0)"

lemma degree[rule_format, intro, simp]:
  shows "∀j≥degree x. pdevs_apply x j = 0"
  unfolding degree_def
proof (rule LeastI_ex)
  have "⋀j. j > Max (pdevs_domain x) ⟹ j ∉ (pdevs_domain x)"
    by (metis Max_less_iff all_not_in_conv less_irrefl_nat finite_pdevs_domain)
  then show "∃xa. ∀j≥xa. pdevs_apply x j = 0"
    by (auto intro!: exI[where x="Max (pdevs_domain x) + 1"])
qed

lemma degree_le:
  assumes d: "∀j ≥ d. pdevs_apply x j = 0"
  shows "degree x ≤ d"
  unfolding degree_def
  by (rule Least_le) (rule d)

lemma degree_gt: "pdevs_apply x j ≠ 0 ⟹ degree x > j"
  by auto

lemma pdevs_val_pdevs_domain: "pdevs_val e X = (∑i∈pdevs_domain X. e i *⇩R pdevs_apply X i)"
  by (auto simp: pdevs_val_def intro!: suminf_finite)

lemma pdevs_val_sum_le: "degree X ≤ d ⟹ pdevs_val e X = (∑i < d. e i *⇩R pdevs_apply X i)"
  by (force intro!: degree_gt sum.mono_neutral_cong_left simp: pdevs_val_pdevs_domain)

lemmas pdevs_val_sum = pdevs_val_sum_le[OF order_refl]

lemma pdevs_val_zero[simp]: "pdevs_val (λ_. 0) x = 0"
  by (auto simp: pdevs_val_sum)

lemma degree_eqI:
  assumes "pdevs_apply x d ≠ 0"
  assumes "⋀j. j > d ⟹ pdevs_apply x j = 0"
  shows "degree x = Suc d"
  unfolding eq_iff
  by (auto intro!: degree_gt degree_le assms simp: Suc_le_eq)

lemma finite_degree_nonzero[intro, simp]: "finite {i. pdevs_apply x i ≠ 0}"
  by transfer (auto simp: vimage_def Collect_neg_eq)

lemma degree_eq_Suc_max:
  "degree x = (if (∀i. pdevs_apply x i = 0) then 0 else Suc (Max {i. pdevs_apply x i ≠ 0}))"
proof -
  {
    assume "⋀i. pdevs_apply x i = 0"
    hence ?thesis
      by auto (metis degree_le le_0_eq)
  } moreover {
    fix i assume "pdevs_apply x i ≠ 0"
    hence ?thesis
      using Max_in[OF finite_degree_nonzero, of x]
      by (auto intro!: degree_eqI) (metis Max.coboundedI[OF finite_degree_nonzero] in_pdevs_domain
        le_eq_less_or_eq less_asym pdevs_domain_def)
  } ultimately show ?thesis
    by blast
qed

lemma pdevs_val_degree_cong:
  assumes "b = d"
  assumes "⋀i. i < degree b ⟹ a i = c i"
  shows "pdevs_val a b = pdevs_val c d"
  using assms
  by (auto simp: pdevs_val_sum)

abbreviation degree_aform::"'a::real_vector aform ⇒ nat"
  where "degree_aform X ≡ degree (snd X)"

lemma degree_cong: "(⋀i. (pdevs_apply x i = 0) = (pdevs_apply y i = 0)) ⟹ degree x = degree y"
  unfolding degree_def
  by auto

lemma Least_True_nat[intro, simp]: "(LEAST i::nat. True) = 0"
  by (metis (lifting) One_nat_def less_one not_less_Least not_less_eq)

lemma sorted_list_of_pdevs_domain_eq:
  "sorted_list_of_set (pdevs_domain X) = filter ((≠) 0 o pdevs_apply X) [0..<degree X]"
  by (auto simp: degree_gt intro!: sorted_distinct_set_unique sorted_filter[of "λx. x", simplified])


subsection ‹Total Deviation›

definition tdev::"'a::ordered_euclidean_space pdevs ⇒ 'a" where
  "tdev x = (∑i<degree x. ¦pdevs_apply x i¦)"

lemma abs_pdevs_val_le_tdev: "e ∈ UNIV → {-1 .. 1} ⟹ ¦pdevs_val e x¦ ≤ tdev x"
  by (force simp: pdevs_val_sum tdev_def abs_scaleR Pi_iff
    intro!: order_trans[OF sum_abs] sum_mono scaleR_left_le_one_le
    intro: abs_leI)


subsection ‹Binary Pointwise Operations›

definition binop_pdevs_raw::"('a::zero ⇒ 'b::zero ⇒ 'c::zero) ⇒
    (nat ⇒ 'a) ⇒ (nat ⇒ 'b) ⇒ nat ⇒ 'c"
  where "binop_pdevs_raw f x y i = (if x i = 0 ∧ y i = 0 then 0 else f (x i) (y i))"

lemma nonzeros_binop_pdevs_subset:
  "{i. binop_pdevs_raw f x y i ≠ 0} ⊆ {i. x i ≠ 0} ∪ {i. y i ≠ 0}"
  by (auto simp: binop_pdevs_raw_def)

lift_definition binop_pdevs::
    "('a ⇒ 'b ⇒ 'c) ⇒ 'a::zero pdevs ⇒ 'b::zero pdevs ⇒ 'c::zero pdevs"
  is binop_pdevs_raw
  using nonzeros_binop_pdevs_subset
  by (rule finite_subset) auto

lemma pdevs_apply_binop_pdevs[simp]: "pdevs_apply (binop_pdevs f x y) i =
  (if pdevs_apply x i = 0 ∧ pdevs_apply y i = 0 then 0 else f (pdevs_apply x i) (pdevs_apply y i))"
  by transfer (auto simp: binop_pdevs_raw_def)


subsection ‹Addition›

definition add_pdevs::"'a::real_vector pdevs ⇒ 'a pdevs ⇒ 'a pdevs"
  where "add_pdevs = binop_pdevs (+)"

lemma pdevs_apply_add_pdevs[simp]:
  "pdevs_apply (add_pdevs X Y) n = pdevs_apply X n + pdevs_apply Y n"
  by (auto simp: add_pdevs_def)

lemma pdevs_val_add_pdevs[simp]:
  fixes x y::"'a::euclidean_space"
  shows "pdevs_val e (add_pdevs X Y) = pdevs_val e X + pdevs_val e Y"
proof -
  let ?sum = "λm X. ∑i < m. e i *⇩R pdevs_apply X i"
  let ?m = "max (degree X) (degree Y)"
  have "pdevs_val e X + pdevs_val e Y = ?sum (degree X) X + ?sum (degree Y) Y"
    by (simp add: pdevs_val_sum)
  also have "?sum (degree X) X = ?sum ?m X"
    by (rule sum.mono_neutral_cong_left) auto
  also have "?sum (degree Y) Y = ?sum ?m Y"
    by (rule sum.mono_neutral_cong_left) auto
  also have "?sum ?m X + ?sum ?m Y = (∑i < ?m. e i *⇩R (pdevs_apply X i + pdevs_apply Y i))"
    by (simp add: scaleR_right_distrib sum.distrib)
  also have "… = (∑i. e i *⇩R (pdevs_apply X i + pdevs_apply Y i))"
    by (rule suminf_finite[symmetric]) auto
  also have "… = pdevs_val e (add_pdevs X Y)"
    by (simp add: pdevs_val_def)
  finally show "pdevs_val e (add_pdevs X Y) = pdevs_val e X + pdevs_val e Y" by simp
qed


subsection ‹Total Deviation›

lemma tdev_eq_zero_iff: fixes X::"real pdevs" shows "tdev X = 0 ⟷ (∀e. pdevs_val e X = 0)"
  by (force simp add: pdevs_val_sum tdev_def sum_nonneg_eq_0_iff
    dest!: spec[where x="λi. if pdevs_apply X i ≥ 0 then 1 else -1"] split: if_split_asm)

lemma tdev_nonneg[intro, simp]: "tdev X ≥ 0"
  by (auto simp: tdev_def)

lemma tdev_nonpos_iff[simp]: "tdev X ≤ 0 ⟷ tdev X = 0"
  by (auto simp: order.antisym)


subsection ‹Unary Operations›

definition unop_pdevs_raw::
    "('a::zero ⇒ 'b::zero) ⇒ (nat ⇒ 'a) ⇒ nat ⇒ 'b"
  where "unop_pdevs_raw f x i = (if x i = 0 then 0 else f (x i))"

lemma nonzeros_unop_pdevs_subset: "{i. unop_pdevs_raw f x i ≠ 0} ⊆ {i. x i ≠ 0}"
  by (auto simp: unop_pdevs_raw_def)

lift_definition unop_pdevs::
    "('a ⇒ 'b) ⇒ 'a::zero pdevs ⇒ 'b::zero pdevs"
  is unop_pdevs_raw
  using nonzeros_unop_pdevs_subset
  by (rule finite_subset) auto

lemma pdevs_apply_unop_pdevs[simp]: "pdevs_apply (unop_pdevs f x) i =
  (if pdevs_apply x i = 0 then 0 else f (pdevs_apply x i))"
  by transfer (auto simp: unop_pdevs_raw_def)

lemma pdevs_domain_unop_linear:
  assumes "linear f"
  shows "pdevs_domain (unop_pdevs f x) ⊆ pdevs_domain x"
proof -
  interpret f: linear f by fact
  show ?thesis
    by (auto simp: f.zero)
qed

lemma
  pdevs_val_unop_linear:
  assumes "linear f"
  shows "pdevs_val e (unop_pdevs f x) = f (pdevs_val e x)"
proof -
  interpret f: linear f by fact
  have *: "⋀i. (if pdevs_apply x i = 0 then 0 else f (pdevs_apply x i)) = f (pdevs_apply x i)"
    by (auto simp: f.zero)
  have "pdevs_val e (unop_pdevs f x) =
      (∑i∈pdevs_domain (unop_pdevs f x). e i *⇩R f (pdevs_apply x i))"
    by (auto simp add: pdevs_val_pdevs_domain *)
  also have "… = (∑xa∈pdevs_domain x. e xa *⇩R f (pdevs_apply x xa))"
    by (auto intro!: sum.mono_neutral_cong_left)
  also have "… = f (pdevs_val e x)"
    by (auto simp add: pdevs_val_pdevs_domain f.sum f.scaleR)
  finally show ?thesis .
qed


subsection ‹Pointwise Scaling of Partial Deviations›

definition scaleR_pdevs::"real ⇒ 'a::real_vector pdevs ⇒ 'a pdevs"
  where "scaleR_pdevs r x = unop_pdevs ((*⇩R) r) x"

lemma pdevs_apply_scaleR_pdevs[simp]:
  "pdevs_apply (scaleR_pdevs x Y) n = x *⇩R pdevs_apply Y n"
  by (auto simp: scaleR_pdevs_def)

lemma degree_scaleR_pdevs[simp]: "degree (scaleR_pdevs r x) = (if r = 0 then 0 else degree x)"
  unfolding degree_def
  by auto

lemma pdevs_val_scaleR_pdevs[simp]:
  fixes x::real and Y::"'a::real_normed_vector pdevs"
  shows "pdevs_val e (scaleR_pdevs x Y) = x *⇩R pdevs_val e Y"
  by (auto simp: pdevs_val_sum scaleR_sum_right ac_simps)


subsection ‹Partial Deviations Scale Pointwise›

definition pdevs_scaleR::"real pdevs ⇒ 'a::real_vector ⇒ 'a pdevs"
  where "pdevs_scaleR r x = unop_pdevs (λr. r *⇩R x) r"

lemma pdevs_apply_pdevs_scaleR[simp]:
  "pdevs_apply (pdevs_scaleR X y) n = pdevs_apply X n *⇩R y"
  by (auto simp: pdevs_scaleR_def)

lemma degree_pdevs_scaleR[simp]: "degree (pdevs_scaleR r x) = (if x = 0 then 0 else degree r)"
  unfolding degree_def
  by auto

lemma pdevs_val_pdevs_scaleR[simp]:
  fixes X::"real pdevs" and y::"'a::real_normed_vector"
  shows "pdevs_val e (pdevs_scaleR X y) = pdevs_val e X *⇩R y"
  by (auto simp: pdevs_val_sum scaleR_sum_left)


subsection ‹Pointwise Unary Minus›

definition uminus_pdevs::"'a::real_vector pdevs ⇒ 'a pdevs"
  where "uminus_pdevs = unop_pdevs uminus"

lemma pdevs_apply_uminus_pdevs[simp]: "pdevs_apply (uminus_pdevs x) = - pdevs_apply x"
  by (auto simp: uminus_pdevs_def)

lemma degree_uminus_pdevs[simp]: "degree (uminus_pdevs x) = degree x"
  by (rule degree_cong) simp

lemma pdevs_val_uminus_pdevs[simp]: "pdevs_val e (uminus_pdevs x) = - pdevs_val e x"
  unfolding pdevs_val_sum
  by (auto simp: sum_negf)

definition "uminus_aform X = (- fst X, uminus_pdevs (snd X))"

lemma fst_uminus_aform[simp]: "fst (uminus_aform Y) = - fst Y"
  by (simp add: uminus_aform_def)

lemma aform_val_uminus_aform[simp]: "aform_val e (uminus_aform X) = - aform_val e X"
  by (auto simp: uminus_aform_def aform_val_def)


subsection ‹Constant›

lift_definition zero_pdevs::"'a::zero pdevs" is "λ_. 0" by simp

lemma pdevs_apply_zero_pdevs[simp]: "pdevs_apply zero_pdevs i = 0"
  by transfer simp

lemma pdevs_val_zero_pdevs[simp]: "pdevs_val e zero_pdevs = 0"
  by (auto simp: pdevs_val_def)

definition "num_aform f = (f, zero_pdevs)"


subsection ‹Inner Product›

definition pdevs_inner::"'a::euclidean_space pdevs ⇒ 'a ⇒ real pdevs"
  where "pdevs_inner x b = unop_pdevs (λx. x ∙ b) x"

lemma pdevs_apply_pdevs_inner[simp]: "pdevs_apply (pdevs_inner p a) i = pdevs_apply p i ∙ a"
  by (simp add: pdevs_inner_def)

lemma pdevs_val_pdevs_inner[simp]: "pdevs_val e (pdevs_inner p a) = pdevs_val e p ∙ a"
  by (auto simp add: inner_sum_left pdevs_val_pdevs_domain intro!: sum.mono_neutral_cong_left)

definition inner_aform::"'a::euclidean_space aform ⇒ 'a ⇒ real aform"
  where "inner_aform X b = (fst X ∙ b, pdevs_inner (snd X) b)"



subsection ‹Inner Product Pair›

definition inner2::"'a::euclidean_space ⇒ 'a ⇒ 'a ⇒ real*real"
  where "inner2 x n l = (x ∙ n, x ∙ l)"

definition pdevs_inner2::"'a::euclidean_space pdevs ⇒ 'a ⇒ 'a ⇒ (real*real) pdevs"
  where "pdevs_inner2 X n l = unop_pdevs (λx. inner2 x n l) X"

lemma pdevs_apply_pdevs_inner2[simp]: "pdevs_apply (pdevs_inner2 p a b) i = (pdevs_apply p i ∙ a, pdevs_apply p i ∙ b)"
  by (simp add: pdevs_inner2_def inner2_def zero_prod_def)

definition inner2_aform::"'a::euclidean_space aform ⇒ 'a ⇒ 'a ⇒ (real*real) aform"
  where "inner2_aform X a b = (inner2 (fst X) a b, pdevs_inner2 (snd X) a b)"

lemma linear_inner2[intro, simp]: "linear (λx. inner2 x n i)"
  by unfold_locales (auto simp: inner2_def algebra_simps)

lemma aform_val_inner2_aform[simp]: "aform_val e (inner2_aform Z n i) = inner2 (aform_val e Z) n i"
proof -
  have "aform_val e (inner2_aform Z n i) = inner2 (fst Z) n i + inner2 (pdevs_val e (snd Z)) n i"
    by (auto simp: aform_val_def inner2_aform_def pdevs_inner2_def pdevs_val_unop_linear)
  also have "… = inner2 (aform_val e Z) n i"
    by (simp add: inner2_def algebra_simps aform_val_def)
  finally show ?thesis .
qed


subsection ‹Update›

lemma pdevs_val_upd[simp]:
  "pdevs_val (e(n := e')) X = pdevs_val e X - e n * pdevs_apply X n + e' * pdevs_apply X n"
  unfolding pdevs_val_def
  by (subst suminf_finite[OF finite.insertI[OF finite_degree_nonzero], of n X],
    auto simp: pdevs_val_def sum.insert_remove)+

lemma nonzeros_fun_upd:
  "{i. (f(n := a)) i ≠ 0} ⊆ {i. f i ≠ 0} ∪ {n}"
  by (auto split: if_split_asm)

lift_definition pdev_upd::"'a::real_vector pdevs ⇒ nat ⇒ 'a ⇒ 'a pdevs"
  is "λx n a. x(n:=a)"
  by (rule finite_subset[OF nonzeros_fun_upd]) simp

lemma pdevs_apply_pdev_upd[simp]:
  "pdevs_apply (pdev_upd X n x) = (pdevs_apply X)(n:=x)"
  by transfer simp

lemma pdevs_val_pdev_upd[simp]:
  "pdevs_val e (pdev_upd X n x) = pdevs_val e X + e n *⇩R x - e n *⇩R pdevs_apply X n"
  unfolding pdevs_val_def
  by (subst suminf_finite[OF finite.insertI[OF finite_degree_nonzero], of n X],
    auto simp: pdevs_val_def sum.insert_remove)+

lemma degree_pdev_upd:
  assumes "x = 0 ⟷ pdevs_apply X n = 0"
  shows "degree (pdev_upd X n x) = degree X"
  using assms
  by (auto intro!: degree_cong split: if_split_asm)

lemma degree_pdev_upd_le:
  assumes "degree X ≤ n"
  shows "degree (pdev_upd X n x) ≤ Suc n"
  using assms
  by (auto intro!: degree_le)


subsection ‹Inf/Sup›

definition "Inf_aform X = fst X - tdev (snd X)"

definition "Sup_aform X = fst X + tdev (snd X)"

lemma Inf_aform:
  assumes "e ∈ UNIV → {-1 .. 1}"
  shows "Inf_aform X ≤ aform_val e X"
  using order_trans[OF abs_ge_minus_self abs_pdevs_val_le_tdev[OF assms]]
  by (auto simp: Inf_aform_def aform_val_def minus_le_iff)

lemma Sup_aform:
  assumes "e ∈ UNIV → {-1 .. 1}"
  shows "aform_val e X ≤ Sup_aform X"
  using order_trans[OF abs_ge_self abs_pdevs_val_le_tdev[OF assms]]
  by (auto simp: Sup_aform_def aform_val_def)


subsection ‹Minkowski Sum›

definition msum_pdevs_raw::"nat⇒(nat ⇒ 'a::real_vector)⇒(nat ⇒ 'a)⇒(nat⇒'a)" where
  "msum_pdevs_raw n x y i = (if i < n then x i else y (i - n))"

lemma nonzeros_msum_pdevs_raw:
  "{i. msum_pdevs_raw n f g i ≠ 0} = ({0..<n} ∩ {i. f i ≠ 0}) ∪ (+) n ` ({i. g i ≠ 0})"
  by (force simp: msum_pdevs_raw_def not_less split: if_split_asm)

lift_definition msum_pdevs::"nat⇒'a::real_vector pdevs⇒'a pdevs⇒'a pdevs" is msum_pdevs_raw
  unfolding nonzeros_msum_pdevs_raw by simp

lemma pdevs_apply_msum_pdevs: "pdevs_apply (msum_pdevs n f g) i =
  (if i < n then pdevs_apply f i else pdevs_apply g (i - n))"
  by transfer (auto simp: msum_pdevs_raw_def)

lemma degree_least_nonzero:
  assumes "degree f ≠ 0"
  shows "pdevs_apply f (degree f - 1) ≠ 0"
proof
  assume H: "pdevs_apply f (degree f - 1) = 0"
  {
    fix j
    assume "j≥degree f - 1"
    with H have "pdevs_apply f j = 0"
      by (cases "degree f - 1 = j") auto
  }
  from degree_le[rule_format, OF this]
  have "degree f ≤ degree f - 1"
    by blast
  with assms show False by simp
qed

lemma degree_leI:
  assumes "(⋀i. pdevs_apply y i = 0 ⟹ pdevs_apply x i = 0)"
  shows "degree x ≤ degree y"
proof cases
  assume "degree x ≠ 0"
  from degree_least_nonzero[OF this]
  have "pdevs_apply y (degree x - 1) ≠ 0"
    by (auto simp: assms split: if_split_asm)
  from degree_gt[OF this] show ?thesis
    by simp
qed simp

lemma degree_msum_pdevs_ge1:
  shows "degree f ≤ n ⟹ degree f ≤ degree (msum_pdevs n f g)"
  by (rule degree_leI) (auto simp: pdevs_apply_msum_pdevs split: if_split_asm)

lemma degree_msum_pdevs_ge2:
  assumes "degree f ≤ n"
  shows "degree g ≤ degree (msum_pdevs n f g) - n"
proof cases
  assume "degree g ≠ 0"
  hence "pdevs_apply g (degree g - 1) ≠ 0" by (rule degree_least_nonzero)
  hence "pdevs_apply (msum_pdevs n f g) (n + degree g - 1) ≠ 0"
    using assms
    by (auto simp: pdevs_apply_msum_pdevs)
  from degree_gt[OF this]
  show ?thesis
    by simp
qed simp

lemma degree_msum_pdevs_le:
  shows "degree (msum_pdevs n f g) ≤ n + degree g"
  by (auto intro!: degree_le simp: pdevs_apply_msum_pdevs)

lemma
  sum_msum_pdevs_cases:
  assumes "degree f ≤ n"
  assumes [simp]: "⋀i. e i 0 = 0"
  shows
    "(∑i <degree (msum_pdevs n f g).
      e i (if i < n then pdevs_apply f i else pdevs_apply g (i - n))) =
    (∑i <degree f. e i (pdevs_apply f i)) + (∑i <degree g. e (i + n) (pdevs_apply g i))"
  (is "?lhs = ?rhs")
proof -
  have "?lhs = (∑i∈{..<degree (msum_pdevs n f g)} ∩ {i. i < n}. e i (pdevs_apply f i)) +
    (∑i∈{..<degree (msum_pdevs n f g)} ∩ - {i. i < n}. e i (pdevs_apply g (i - n)))"
    (is "_ = ?sum_f + ?sum_g")
     by (simp add: sum.If_cases if_distrib)
  also have "?sum_f = (∑i = 0..<degree f. e i (pdevs_apply f i))"
    using assms degree_msum_pdevs_ge1[of f n g]
    by (intro sum.mono_neutral_cong_right) auto
  also
  have "?sum_g = (∑i∈{0 + n..<degree (msum_pdevs n f g) - n + n}. e i (pdevs_apply g (i - n)))"
    by (rule sum.cong) auto
  also have "… = (∑i = 0..<degree (msum_pdevs n f g) - n. e (i + n) (pdevs_apply g (i + n - n)))"
    by (rule sum.shift_bounds_nat_ivl)
  also have "… = (∑i = 0..<degree g. e (i + n) (pdevs_apply g i))"
    using assms degree_msum_pdevs_ge2[of f n]
    by (intro sum.mono_neutral_cong_right) (auto intro!: sum.mono_neutral_cong_right)
  finally show ?thesis
    by (simp add: atLeast0LessThan)
qed

lemma tdev_msum_pdevs: "degree f ≤ n ⟹ tdev (msum_pdevs n f g) = tdev f + tdev g"
  by (auto simp: tdev_def pdevs_apply_msum_pdevs intro!: sum_msum_pdevs_cases)

lemma pdevs_val_msum_pdevs:
  "degree f ≤ n ⟹ pdevs_val e (msum_pdevs n f g) = pdevs_val e f + pdevs_val (λi. e (i + n)) g"
  by (auto simp: pdevs_val_sum pdevs_apply_msum_pdevs intro!: sum_msum_pdevs_cases)

definition msum_aform::"nat ⇒ 'a::real_vector aform ⇒ 'a aform ⇒ 'a aform"
  where "msum_aform n f g = (fst f + fst g, msum_pdevs n (snd f) (snd g))"

lemma fst_msum_aform[simp]: "fst (msum_aform n f g) = fst f + fst g"
  by (simp add: msum_aform_def)

lemma snd_msum_aform[simp]: "snd (msum_aform n f g) = msum_pdevs n (snd f) (snd g)"
  by (simp add: msum_aform_def)

lemma finite_nonzero_summable: "finite {i. f i ≠ 0} ⟹ summable f"
  by (auto intro!: sums_summable sums_finite)

lemma aform_val_msum_aform:
  assumes "degree_aform f ≤ n"
  shows "aform_val e (msum_aform n f g) = aform_val e f + aform_val (λi. e (i + n)) g"
  using assms
  by (auto simp: pdevs_val_msum_pdevs aform_val_def)

lemma Inf_aform_msum_aform:
  "degree_aform X ≤ n ⟹ Inf_aform (msum_aform n X Y) = Inf_aform X + Inf_aform Y"
  by (simp add: Inf_aform_def tdev_msum_pdevs)

lemma Sup_aform_msum_aform:
  "degree_aform X ≤ n ⟹ Sup_aform (msum_aform n X Y) = Sup_aform X + Sup_aform Y"
  by (simp add: Sup_aform_def tdev_msum_pdevs)

definition "independent_from d Y = msum_aform d (0, zero_pdevs) Y"

definition "independent_aform X Y = independent_from (degree_aform X) Y"

lemma degree_zero_pdevs[simp]: "degree zero_pdevs = 0"
  by (metis degree_least_nonzero pdevs_apply_zero_pdevs)

lemma independent_aform_Joints:
  assumes "x ∈ Affine X"
  assumes "y ∈ Affine Y"
  shows "[x, y] ∈ Joints [X, independent_aform X Y]"
  using assms
  unfolding Affine_def valuate_def Joints_def
  apply safe
  subgoal premises prems for e ea
    using prems
    by (intro image_eqI[where x="λi. if i < degree_aform X then e i else ea (i - degree_aform X)"])
      (auto simp: aform_val_def pdevs_val_msum_pdevs Pi_iff
      independent_aform_def independent_from_def intro!: pdevs_val_degree_cong)
  done

lemma msum_aform_Joints:
  assumes "d ≥ degree_aform X"
  assumes "⋀X. X ∈ set XS ⟹ d ≥ degree_aform X"
  assumes "(x#xs) ∈ Joints (X#XS)"
  assumes "y ∈ Affine Y"
  shows "((x + y)#x#xs) ∈ Joints (msum_aform d X Y#X#XS)"
  using assms
  unfolding Joints_def valuate_def Affine_def
proof (safe, goal_cases)
  case (1 e ea a b zs)
  then show ?case
    by (intro image_eqI[where x = "λi. if i < d then e i else ea (i - d)"])
      (force simp: aform_val_def pdevs_val_msum_pdevs intro!: intro!: pdevs_val_degree_cong)+
qed

lemma Joints_msum_aform:
  assumes "d ≥ degree_aform X"
  assumes "⋀Y. Y ∈ set YS ⟹ d ≥ degree_aform Y"
  shows "Joints (msum_aform d X Y#YS) = {((x + y)#ys) |x y ys. y ∈ Affine Y ∧ x#ys ∈ Joints (X#YS)}"
  unfolding Affine_def valuate_def Joints_def
proof (safe, goal_cases)
  case (1 x e)
  thus ?case
    using assms
    by (intro exI[where x = "aform_val e X"] exI[where x = "aform_val ((λi. e (i + d))) Y"])
      (auto simp add: aform_val_def pdevs_val_msum_pdevs)
next
  case (2 x xa y ys e ea)
  thus ?case using assms
    by (intro image_eqI[where x="λi. if i < d then ea i else e (i - d)"])
       (force simp: aform_val_def pdevs_val_msum_pdevs Pi_iff intro!: pdevs_val_degree_cong)+
qed

lemma Joints_singleton_image: "Joints [x] = (λx. [x]) ` Affine x"
  by (auto simp: Joints_def Affine_def valuate_def)

lemma Collect_extract_image: "{g (f x y) |x y. P x y} = g ` {f x y |x y. P x y}"
  by auto

lemma inj_Cons: "inj (λx. x#xs)"
  by (auto intro!: injI)

lemma Joints_Nil[simp]: "Joints [] = {[]}"
  by (force simp: Joints_def valuate_def)

lemma msum_pdevs_zero_ident[simp]: "msum_pdevs 0 zero_pdevs x = x"
  by transfer (auto simp: msum_pdevs_raw_def)

lemma msum_aform_zero_ident[simp]: "msum_aform 0 (0, zero_pdevs) x = x"
  by (simp add: msum_aform_def)

lemma mem_Joints_singleton: "(x ∈ Joints [X]) = (∃y. x = [y] ∧ y ∈ Affine X)"
  by (auto simp: Affine_def valuate_def Joints_def)

lemma singleton_mem_Joints[simp]: "[x] ∈ Joints [X] ⟷ x ∈ Affine X"
  by (auto simp: mem_Joints_singleton)

lemma msum_aform_Joints_without_first:
  assumes "d ≥ degree_aform X"
  assumes "⋀X. X ∈ set XS ⟹ d ≥ degree_aform X"
  assumes "(x#xs) ∈ Joints (X#XS)"
  assumes "y ∈ Affine Y"
  assumes "z = x + y"
  shows "z#xs ∈ Joints (msum_aform d X Y#XS)"
  unfolding ‹z = x + y›
  using msum_aform_Joints[OF assms(1-4)]
  by (force simp: Joints_def valuate_def)

lemma Affine_msum_aform:
  assumes "d ≥ degree_aform X"
  shows "Affine (msum_aform d X Y) = {x + y |x y. x ∈ Affine X ∧ y ∈ Affine Y}"
  using Joints_msum_aform[OF assms, of Nil Y, simplified, unfolded mem_Joints_singleton]
  by (auto simp add: Joints_singleton_image Collect_extract_image[where g="λx. [x]"]
    inj_image_eq_iff[OF inj_Cons] )

lemma Affine_zero_pdevs[simp]: "Affine (0, zero_pdevs) = {0}"
  by (force simp: Affine_def valuate_def aform_val_def)

lemma Affine_independent_aform:
  "Affine (independent_aform X Y) = Affine Y"
  by (auto simp: independent_aform_def independent_from_def Affine_msum_aform)

lemma
  abs_diff_eq1:
  fixes l u::"'a::ordered_euclidean_space"
  shows "l ≤ u ⟹ ¦u - l¦ = u - l"
  by (metis abs_of_nonneg diff_add_cancel le_add_same_cancel2)

lemma compact_sum:
  fixes f :: "'a ⇒ 'b::topological_space ⇒ 'c::real_normed_vector"
  assumes "finite I"
  assumes "⋀i. i ∈ I ⟹ compact (S i)"
  assumes "⋀i. i ∈ I ⟹ continuous_on (S i) (f i)"
  assumes "I ⊆ J"
  shows "compact {∑i∈I. f i (x i) | x. x ∈ Pi J S}"
  using assms
proof (induct I)
  case empty
  thus ?case
  proof (cases "∃x. x ∈ Pi J S")
    case False
    hence *: "{∑i∈{}. f i (x i) |x. x ∈ Pi J S} = {}"
      by (auto simp: Pi_iff)
    show ?thesis unfolding * by simp
  qed auto
next
  case (insert a I)
  hence "{∑i∈insert a I. f i (xa i) |xa. xa ∈ Pi J S}
    = {x + y |x y. x ∈ f a ` S a ∧ y ∈ {∑i∈I. f i (x i) |x. x ∈ Pi J S}}"
  proof safe
    fix s x
    assume "s ∈ S a" "x ∈ Pi J S"
    thus "∃xa. f a s + (∑i∈I. f i (x i)) = (∑i∈insert a I. f i (xa i)) ∧ xa ∈ Pi J S"
      using insert
      by (auto intro!: exI[where x="x(a:=s)"] sum.cong)
  qed force
  also have "compact …"
    using insert
    by (intro compact_sums) (auto intro!: compact_continuous_image)
  finally show ?case .
qed

lemma compact_Affine:
  fixes X::"'a::ordered_euclidean_space aform"
  shows "compact (Affine X)"
proof -
  have "Affine X = {x + y|x y. x ∈ {fst X} ∧
      y ∈ {(∑i ∈ {0..<degree_aform X}. e i *⇩R pdevs_apply (snd X) i) | e. e ∈ UNIV → {-1 .. 1}}}"
    by (auto simp: Affine_def valuate_def aform_val_def pdevs_val_sum atLeast0LessThan)
  also have "compact …"
    by (rule compact_sums) (auto intro!: compact_sum continuous_intros)
  finally show ?thesis .
qed

lemma Joints2_JointsI:
  "(xs, x) ∈ Joints2 XS X ⟹ x#xs ∈ Joints (X#XS)"
  by (auto simp: Joints_def Joints2_def valuate_def)


subsection ‹Splitting›

definition "split_aform X i =
  (let xi = pdevs_apply (snd X) i /⇩R 2
  in ((fst X - xi, pdev_upd (snd X) i xi), (fst X + xi, pdev_upd (snd X) i xi)))"

lemma split_aformE:
  assumes "e ∈ UNIV → {-1 .. 1}"
  assumes "x = aform_val e X"
  obtains err where "x = aform_val (e(i:=err)) (fst (split_aform X i))" "err ∈ {-1 .. 1}"
    | err where "x = aform_val (e(i:=err)) (snd (split_aform X i))" "err ∈ {-1 .. 1}"
proof (atomize_elim)
  let ?thesis = "(∃err. x = aform_val (e(i := err)) (fst (split_aform X i)) ∧ err ∈ {- 1..1}) ∨
    (∃err. x = aform_val (e(i := err)) (snd (split_aform X i)) ∧ err ∈ {- 1..1})"
  {
    assume "pdevs_apply (snd X) i = 0"
    hence "X = fst (split_aform X i)"
      by (auto simp: split_aform_def intro!: prod_eqI pdevs_eqI)
    with assms have ?thesis by (auto intro!: exI[where x="e i"])
  } moreover {
    assume "pdevs_apply (snd X) i ≠ 0"
    hence [simp]: "degree_aform X > i"
      by (rule degree_gt)
    note assms(2)
    also
    have "aform_val e X = fst X + (∑i<degree_aform X. e i *⇩R pdevs_apply (snd X) i)"
      by (simp add: aform_val_def pdevs_val_sum)
    also
    have rewr: "{..<degree_aform X} = {0..<degree_aform X} - {i} ∪ {i}"
      by auto
    have "(∑i<degree_aform X. e i *⇩R pdevs_apply (snd X) i) =
        (∑i ∈ {0..<degree_aform X} - {i}. e i *⇩R pdevs_apply (snd X) i) +
        e i *⇩R pdevs_apply (snd X) i"
      by (subst rewr, subst sum.union_disjoint) auto
    finally have "x = fst X + …" .
    hence "x = aform_val (e(i:=2 * e i - 1)) (snd (split_aform X i))"
        "x = aform_val (e(i:=2 * e i + 1)) (fst (split_aform X i))"
      by (auto simp: aform_val_def split_aform_def Let_def pdevs_val_sum atLeast0LessThan
        Diff_eq degree_pdev_upd if_distrib sum.If_cases field_simps
        scaleR_left_distrib[symmetric])
    moreover
    have "2 * e i - 1 ∈ {-1 .. 1} ∨ 2 * e i + 1 ∈ {-1 .. 1}"
      using assms by (auto simp: not_le Pi_iff dest!: spec[where x=i])
    ultimately have ?thesis by blast
  } ultimately show ?thesis by blast
qed

lemma pdevs_val_add: "pdevs_val (λi. e i + f i) xs = pdevs_val e xs + pdevs_val f xs"
  by (auto simp: pdevs_val_pdevs_domain algebra_simps sum.distrib)

lemma pdevs_val_minus: "pdevs_val (λi. e i - f i) xs = pdevs_val e xs - pdevs_val f xs"
  by (auto simp: pdevs_val_pdevs_domain algebra_simps sum_subtractf)

lemma pdevs_val_cmul: "pdevs_val (λi. u * e i) xs = u *⇩R pdevs_val e xs"
  by (auto simp: pdevs_val_pdevs_domain scaleR_sum_right)

lemma atLeastAtMost_absI: "- a ≤ a ⟹ ¦x::real¦ ≤ ¦a¦ ⟹ x ∈ atLeastAtMost (- a) a"
  by auto

lemma divide_atLeastAtMost_1_absI: "¦x::real¦ ≤ ¦a¦ ⟹ x/a ∈ {-1 .. 1}"
  by (intro atLeastAtMost_absI) (auto simp: divide_le_eq_1)

lemma convex_scaleR_aux: "u + v = 1 ⟹ u *⇩R x + v *⇩R x = (x::'a::real_vector)"
  by (metis scaleR_add_left scaleR_one)

lemma convex_mult_aux: "u + v = 1 ⟹ u * x + v * x = (x::real)"
  using convex_scaleR_aux[of u v x] by simp

lemma convex_Affine: "convex (Affine X)"
proof (rule convexI)
  fix x y::'a and u v::real
  assume "x ∈ Affine X" "y ∈ Affine X" and convex: "0 ≤ u" "0 ≤ v" "u + v = 1"
  then obtain e f where x: "x = aform_val e X" "e ∈ UNIV → {-1 .. 1}"
    and y: "y = aform_val f X" "f ∈ UNIV → {-1 .. 1}"
    by (auto simp: Affine_def valuate_def)
  let ?conv = "λi. u * e i + v * f i"
  {
    fix i
    have "¦?conv i¦ ≤ u * ¦e i¦ + v * ¦f i¦"
      using convex by (intro order_trans[OF abs_triangle_ineq]) (simp add: abs_mult)
    also have "… ≤ 1"
      using convex x y
      by (intro convex_bound_le) (auto simp: Pi_iff abs_real_def)
    finally have "?conv i ≤ 1" "-1 ≤ ?conv i"
      by (auto simp: abs_real_def split: if_split_asm)
  }
  thus "u *⇩R x + v *⇩R y ∈ Affine X"
    using convex x y
    by (auto simp: Affine_def valuate_def aform_val_def pdevs_val_add pdevs_val_cmul algebra_simps
      convex_scaleR_aux intro!: image_eqI[where x="?conv"])
qed

lemma segment_in_aform_val:
  assumes "e ∈ UNIV → {-1 .. 1}"
  assumes "f ∈ UNIV → {-1 .. 1}"
  shows "closed_segment (aform_val e X) (aform_val f X) ⊆ Affine X"
proof -
  have "aform_val e X ∈ Affine X" "aform_val f X ∈ Affine X"
    using assms by (auto simp: Affine_def valuate_def)
  with convex_Affine[of X, simplified convex_contains_segment]
  show ?thesis
    by simp
qed


subsection ‹From List of Generators›

lift_definition pdevs_of_list::"'a::zero list ⇒ 'a pdevs"
  is "λxs i. if i < length xs then xs ! i else 0"
  by auto

lemma pdevs_apply_pdevs_of_list:
  "pdevs_apply (pdevs_of_list xs) i = (if i < length xs then xs ! i else 0)"
  by transfer simp

lemma pdevs_apply_pdevs_of_list_Nil[simp]:
  "pdevs_apply (pdevs_of_list []) i = 0"
  by transfer auto

lemma pdevs_apply_pdevs_of_list_Cons:
  "pdevs_apply (pdevs_of_list (x # xs)) i =
    (if i = 0 then x else pdevs_apply (pdevs_of_list xs) (i - 1))"
  by transfer auto

lemma pdevs_domain_pdevs_of_list_Cons[simp]: "pdevs_domain (pdevs_of_list (x # xs)) =
  (if x = 0 then {} else {0}) ∪ (+) 1 ` pdevs_domain (pdevs_of_list xs)"
  by (force simp: pdevs_apply_pdevs_of_list_Cons split: if_split_asm)

lemma pdevs_val_pdevs_of_list_eq[simp]:
  "pdevs_val e (pdevs_of_list (x # xs)) = e 0 *⇩R x + pdevs_val (e o (+) 1) (pdevs_of_list xs)"
proof -
  have "pdevs_val e (pdevs_of_list (x # xs)) =
    (∑i∈pdevs_domain (pdevs_of_list (x # xs)) ∩ {0}. e i *⇩R x) +
    (∑i∈pdevs_domain (pdevs_of_list (x # xs)) ∩ - {0}.
      e i *⇩R pdevs_apply (pdevs_of_list xs) (i - Suc 0))"
    (is "_ = ?l + ?r")
    by (simp add: pdevs_val_pdevs_domain if_distrib sum.If_cases pdevs_apply_pdevs_of_list_Cons)
  also
  have "?r = (∑i∈pdevs_domain (pdevs_of_list xs). e (Suc i) *⇩R pdevs_apply (pdevs_of_list xs) i)"
    by (rule sum.reindex_cong[of "λi. i + 1"]) auto
  also have "… = pdevs_val (e o (+) 1) (pdevs_of_list xs)"
    by (simp add: pdevs_val_pdevs_domain  )
  also have "?l = (∑i∈{0}. e i *⇩R x)"
    by (rule sum.mono_neutral_cong_left) auto
  also have "… = e 0 *⇩R x" by simp
  finally show ?thesis .
qed

lemma
  less_degree_pdevs_of_list_imp_less_length:
  assumes "i < degree (pdevs_of_list xs)"
  shows "i < length xs"
proof -
  from assms have "pdevs_apply (pdevs_of_list xs) (degree (pdevs_of_list xs) - 1) ≠ 0"
    by (metis degree_least_nonzero less_nat_zero_code)
  hence "degree (pdevs_of_list xs) - 1 < length xs"
    by (simp add: pdevs_apply_pdevs_of_list split: if_split_asm)
  with assms show ?thesis
    by simp
qed

lemma tdev_pdevs_of_list[simp]: "tdev (pdevs_of_list xs) = sum_list (map abs xs)"
  by (auto simp: tdev_def pdevs_apply_pdevs_of_list sum_list_sum_nth
    less_degree_pdevs_of_list_imp_less_length
    intro!: sum.mono_neutral_cong_left degree_gt)

lemma pdevs_of_list_Nil[simp]: "pdevs_of_list [] = zero_pdevs"
  by (auto intro!: pdevs_eqI)

lemma pdevs_val_inj_sumI:
  fixes K::"'a set" and g::"'a ⇒ nat"
  assumes "finite K"
  assumes "inj_on g K"
  assumes "pdevs_domain x ⊆ g ` K"
  assumes "⋀i. i ∈ K ⟹ g i ∉ pdevs_domain x ⟹ f i = 0"
  assumes "⋀i. i ∈ K ⟹ g i ∈ pdevs_domain x ⟹ f i = e (g i) *⇩R pdevs_apply x (g i)"
  shows "pdevs_val e x = (∑i∈K. f i)"
proof -
  have [simp]: "inj_on (the_inv_into K g) (pdevs_domain x)"
    using assms
    by (auto simp: intro!: subset_inj_on[OF inj_on_the_inv_into])
  {
    fix y assume y: "y ∈ pdevs_domain x"
    have g_inv: "g (the_inv_into K g y) = y"
      by (meson assms(2) assms(3) y f_the_inv_into_f subset_eq)
    have inv_in: "the_inv_into K g y ∈ K"
      by (meson assms(2) assms(3) y subset_iff in_pdevs_domain the_inv_into_into)
    have inv3: "the_inv_into (pdevs_domain x) (the_inv_into K g) (the_inv_into K g y) =
        g (the_inv_into K g y)"
      using assms y
      by (subst the_inv_into_f_f) (auto simp: f_the_inv_into_f[OF assms(2)])
    note g_inv inv_in inv3
  } note this[simp]
  have "pdevs_val e x = (∑i∈pdevs_domain x. e i *⇩R pdevs_apply x i)"
    by (simp add: pdevs_val_pdevs_domain)
  also have "… = (∑i ∈ the_inv_into K g ` pdevs_domain x. e (g i) *⇩R pdevs_apply x (g i))"
    by (rule sum.reindex_cong[OF inj_on_the_inv_into]) auto
  also have "… = (∑i∈K. f i)"
    using assms
    by (intro sum.mono_neutral_cong_left) (auto simp: the_inv_into_image_eq)
  finally show ?thesis .
qed

lemma pdevs_domain_pdevs_of_list_le: "pdevs_domain (pdevs_of_list xs) ⊆ {0..<length xs}"
  by (auto simp: pdevs_apply_pdevs_of_list split: if_split_asm)

lemma pdevs_val_zip: "pdevs_val e (pdevs_of_list xs) = (∑(i,x)←zip [0..<length xs] xs. e i *⇩R x)"
  by (auto simp: sum_list_distinct_conv_sum_set
    in_set_zip image_fst_zip pdevs_apply_pdevs_of_list distinct_zipI1
    intro!: pdevs_val_inj_sumI[of _ fst]
    split: if_split_asm)

lemma pdevs_val_map:
  ‹pdevs_val e (pdevs_of_list xs)
    = (∑n←[0..<length xs]. e n *⇩R xs ! n)›
proof -
  have ‹map2 (λi. (*⇩R) (e i)) [0..<length xs] xs =
    map (λn. e n *⇩R xs ! n) [0..<length xs]›
    by (rule nth_equalityI) simp_all
  then show ?thesis
    by (simp add: pdevs_val_zip)
qed

lemma scaleR_sum_list:
  fixes xs::"'a::real_vector list"
  shows "a *⇩R sum_list xs = sum_list (map (scaleR a) xs)"
  by (induct xs) (auto simp: algebra_simps)

lemma pdevs_val_const_pdevs_of_list: "pdevs_val (λ_. c) (pdevs_of_list xs) = c *⇩R sum_list xs"
  unfolding pdevs_val_zip split_beta' scaleR_sum_list
  by (rule arg_cong) (auto intro!: nth_equalityI)

lemma pdevs_val_partition:
  assumes "e ∈ UNIV → I"
  obtains f g where "pdevs_val e (pdevs_of_list xs) =
    pdevs_val f (pdevs_of_list (filter p xs)) +
    pdevs_val g (pdevs_of_list (filter (Not o p) xs))"
    "f ∈ UNIV → I"
    "g ∈ UNIV → I"
proof -
  obtain i where i: "i ∈ I"
    by (metis assms funcset_mem iso_tuple_UNIV_I)
  let ?zip = "zip [0..<length xs] xs"
  define part where "part = partition (p ∘ snd) ?zip"
  let ?f =
    "(λn. if n < degree (pdevs_of_list (filter p xs)) then e (map fst (fst part) ! n) else i)"
  let ?g =
    "(λn. if n < degree (pdevs_of_list (filter (Not ∘ p) xs))
      then e (map fst (snd part) ! n)
      else i)"
  show ?thesis
  proof
    have "pdevs_val e (pdevs_of_list xs) = (∑(i,x)←?zip. e i *⇩R x)"
      by (rule pdevs_val_zip)
    also have "… = (∑(i, x)∈set ?zip. e i *⇩R x)"
      by (simp add: sum_list_distinct_conv_sum_set distinct_zipI1)
    also
    have [simp]: "set (fst part) ∩ set (snd part) = {}"
      by (auto simp: part_def)
    from partition_set[of "p o snd" ?zip "fst part" "snd part"]
    have "set ?zip = set (fst part) ∪ set (snd part)"
      by (auto simp: part_def)
    also have "(∑a∈set (fst part) ∪ set (snd part). case a of (i, x) ⇒ e i *⇩R x) =
        (∑(i, x)∈set (fst part). e i *⇩R x) + (∑(i, x)∈set (snd part). e i *⇩R x)"
      by (auto simp: split_beta sum_Un)
    also
    have "(∑(i, x)∈set (fst part). e i *⇩R x) = (∑(i, x)←(fst part). e i *⇩R x)"
      by (simp add: sum_list_distinct_conv_sum_set distinct_zipI1 part_def)
    also have "… = (∑i<length (fst part). case (fst part ! i) of (i, x) ⇒ e i *⇩R x)"
      by (subst sum_list_sum_nth) (simp add: split_beta' atLeast0LessThan)
    also have "… =
      pdevs_val (λn. e (map fst (fst part) ! n)) (pdevs_of_list (map snd (fst part)))"
      by (force
        simp: pdevs_val_zip sum_list_distinct_conv_sum_set distinct_zipI1 split_beta' in_set_zip
        intro!:
          sum.reindex_cong[where l=fst] image_eqI[where x = "(x, map snd (fst part) ! x)" for x])
    also
    have "(∑(i, x)∈set (snd part). e i *⇩R x) = (∑(i, x)←(snd part). e i *⇩R x)"
      by (simp add: sum_list_distinct_conv_sum_set distinct_zipI1 part_def)
    also have "… = (∑i<length (snd part). case (snd part ! i) of (i, x) ⇒ e i *⇩R x)"
      by (subst sum_list_sum_nth) (simp add: split_beta' atLeast0LessThan)
    also have "… =
      pdevs_val (λn. e (map fst (snd part) ! n)) (pdevs_of_list (map snd (snd part)))"
      by (force simp: pdevs_val_zip sum_list_distinct_conv_sum_set distinct_zipI1 split_beta'
        in_set_zip
        intro!: sum.reindex_cong[where l=fst]
          image_eqI[where x = "(x, map snd (snd part) ! x)" for x])
    also
    have "pdevs_val (λn. e (map fst (fst part) ! n)) (pdevs_of_list (map snd (fst part))) =
      pdevs_val (λn.
          if n < degree (pdevs_of_list (map snd (fst part))) then e (map fst (fst part) ! n) else i)
        (pdevs_of_list (map snd (fst part)))"
      by (rule pdevs_val_degree_cong) simp_all
    also
    have "pdevs_val (λn. e (map fst (snd part) ! n)) (pdevs_of_list (map snd (snd part))) =
      pdevs_val (λn.
          if n < degree (pdevs_of_list (map snd (snd part))) then e (map fst (snd part) ! n) else i)
        (pdevs_of_list (map snd (snd part)))"
      by (rule pdevs_val_degree_cong) simp_all
    also have "map snd (snd part) = filter (Not o p) xs"
      by (simp add: part_def filter_map[symmetric] o_assoc)
    also have "map snd (fst part) = filter p xs"
      by (simp add: part_def filter_map[symmetric])
    finally
    show
      "pdevs_val e (pdevs_of_list xs) =
        pdevs_val ?f (pdevs_of_list (filter p xs)) +
        pdevs_val ?g (pdevs_of_list (filter (Not ∘ p) xs))" .
    show "?f ∈ UNIV → I" "?g ∈ UNIV → I"
      using assms ‹i∈I›
      by (auto simp: Pi_iff)
  qed
qed

lemma pdevs_apply_pdevs_of_list_append:
  "pdevs_apply (pdevs_of_list (xs @ zs)) i =
    (if i < length xs
    then pdevs_apply (pdevs_of_list xs) i else pdevs_apply (pdevs_of_list zs) (i - length xs))"
  by (auto simp: pdevs_apply_pdevs_of_list nth_append)

lemma degree_pdevs_of_list_le_length[intro, simp]: "degree (pdevs_of_list xs) ≤ length xs"
  by (metis less_irrefl_nat le_less_linear less_degree_pdevs_of_list_imp_less_length)

lemma degree_pdevs_of_list_append:
  "degree (pdevs_of_list (xs @ ys)) ≤ length xs + degree (pdevs_of_list ys)"
  by (rule degree_le) (auto simp: pdevs_apply_pdevs_of_list_append)

lemma pdevs_val_pdevs_of_list_append:
  assumes "f ∈ UNIV → I"
  assumes "g ∈ UNIV → I"
  obtains e where
    "pdevs_val f (pdevs_of_list xs) + pdevs_val g (pdevs_of_list ys) =
      pdevs_val e (pdevs_of_list (xs @ ys))"
    "e ∈ UNIV → I"
proof
  let ?e = "(λi. if i < length xs then f i else g (i - length xs))"
  have f: "pdevs_val f (pdevs_of_list xs) =
      (∑i∈{..<length xs}. ?e i *⇩R pdevs_apply (pdevs_of_list (xs @ ys)) i)"
    by (auto simp: pdevs_val_sum degree_gt pdevs_apply_pdevs_of_list_append
      intro: sum.mono_neutral_cong_left)
  have g: "pdevs_val g (pdevs_of_list ys) =
      (∑i=length xs ..<length xs + degree (pdevs_of_list ys).
        ?e i *⇩R pdevs_apply (pdevs_of_list (xs @ ys)) i)"
    (is "_ = ?sg")
    by (auto simp: pdevs_val_sum pdevs_apply_pdevs_of_list_append
      intro!: inj_onI image_eqI[where x="length xs + x" for x]
        sum.reindex_cong[where l="λi. i - length xs"])
  show "pdevs_val f (pdevs_of_list xs) + pdevs_val g (pdevs_of_list ys) =
      pdevs_val ?e (pdevs_of_list (xs @ ys))"
    unfolding f g
    by (subst sum.union_disjoint[symmetric])
      (force simp: pdevs_val_sum ivl_disj_un degree_pdevs_of_list_append
        intro!: sum.mono_neutral_cong_right
        split: if_split_asm)+
  show "?e ∈ UNIV → I"
    using assms by (auto simp: Pi_iff)
qed

lemma
  sum_general_mono:
  fixes f::"'a⇒('b::ordered_ab_group_add)"
  assumes [simp,intro]: "finite s" "finite t"
  assumes f: "⋀x. x ∈ s - t ⟹ f x ≤ 0"
  assumes g: "⋀x. x ∈ t - s ⟹ g x ≥ 0"
  assumes fg: "⋀x. x ∈ s ∩ t ⟹ f x ≤ g x"
  shows "(∑x ∈ s. f x) ≤ (∑x ∈ t. g x)"
proof -
  have "s = (s - t) ∪ (s ∩ t)" and [intro, simp]: "(s - t) ∩ (s ∩ t) = {}" by auto
  hence "(∑x ∈ s. f x) = (∑x ∈ s - t ∪ s ∩ t. f x)"
    using assms by simp
  also have "… = (∑x ∈ s - t. f x) + (∑x ∈ s ∩ t. f x)"
    by (simp add: sum_Un)
  also have "(∑x ∈ s - t. f x) ≤ 0"
    by (auto intro!: sum_nonpos f)
  also have "0 ≤ (∑x ∈ t - s. g x)"
    by (auto intro!: sum_nonneg g)
  also have "(∑x ∈ s ∩ t. f x) ≤ (∑x ∈ s ∩ t. g x)"
    by (auto intro!: sum_mono fg)
  also
  have [intro, simp]: "(t - s) ∩ (s ∩ t) = {}" by auto
  hence "sum g (t - s) + sum g (s ∩ t) = sum g ((t - s) ∪ (s ∩ t))"
    by (simp add: sum_Un)
  also have "… = sum g t"
    by (auto intro!: sum.cong)
  finally show ?thesis by simp
qed

lemma degree_pdevs_of_list_eq':
  ‹degree (pdevs_of_list xs) = Min {n. n ≤ length xs ∧ (∀m. n ≤ m ⟶ m < length xs ⟶ xs ! m = 0)}›
  apply (simp add: degree_def pdevs_apply_pdevs_of_list)
  apply (rule Least_equality)
   apply auto
   apply (subst (asm) Min_le_iff)
     apply auto
  apply (subst Min_le_iff)
    apply auto
  apply (metis le_cases not_less)
  done

lemma pdevs_val_permuted:
  ‹pdevs_val (e ∘ p) (pdevs_of_list (permute_list p xs)) = pdevs_val e (pdevs_of_list xs)› (is ‹?r = ?s›)
  if perm: ‹p permutes {..<length xs}›
proof -
  from that have ‹image_mset p (mset_set {0..<length xs}) = mset_set {0..<length xs}›
    by (simp add: permutes_image_mset lessThan_atLeast0)
  moreover have ‹map (λn. e (p n) *⇩R permute_list p xs ! n) [0..<length xs] =
    map (λn. e n *⇩R xs ! n) (map p [0..<length xs])›
    using that by (simp add: permute_list_nth)
  ultimately show ?thesis
    using that by (simp add: pdevs_apply_pdevs_of_list pdevs_val_map
      flip: map_map sum_mset_sum_list)
qed

lemma pdevs_val_perm_ex:
  assumes "xs <~~> ys"
  assumes mem: "e ∈ UNIV → I"
  shows "∃e'. e' ∈ UNIV → I ∧ pdevs_val e (pdevs_of_list xs) = pdevs_val e' (pdevs_of_list ys)"
proof -
  from ‹mset xs = mset ys›
  have ‹mset ys = mset xs› ..
  then obtain p where ‹p permutes {..<length xs}› ‹permute_list p xs = ys›
    by (rule mset_eq_permutation)
  moreover define e' where ‹e' = e ∘ p›
  ultimately have ‹e' ∈ UNIV → I› ‹pdevs_val e (pdevs_of_list xs) = pdevs_val e' (pdevs_of_list ys)›
    using mem by (auto simp add: pdevs_val_permuted)
  then show ?thesis by blast
qed

lemma pdevs_val_perm:
  assumes "xs <~~> ys"
  assumes mem: "e ∈ UNIV → I"
  obtains e' where "e' ∈ UNIV → I"
    "pdevs_val e (pdevs_of_list xs) = pdevs_val e' (pdevs_of_list ys)"
  using assms
  by (metis pdevs_val_perm_ex)

lemma set_distinct_permI: "set xs = set ys ⟹ distinct xs ⟹ distinct ys ⟹ xs <~~> ys"
  by (metis eq_set_perm_remdups remdups_id_iff_distinct)

lemmas pdevs_val_permute = pdevs_val_perm[OF set_distinct_permI]

lemma partition_permI:
  "filter p xs @ filter (Not o p) xs <~~> xs"
  by simp

lemma pdevs_val_eqI:
  assumes "⋀i. i ∈ pdevs_domain y ⟹ i ∈ pdevs_domain x ⟹
      e i *⇩R pdevs_apply x i = f i *⇩R pdevs_apply y i"
  assumes "⋀i. i ∈ pdevs_domain y ⟹ i ∉ pdevs_domain x ⟹ f i *⇩R pdevs_apply y i = 0"
  assumes "⋀i. i ∈ pdevs_domain x ⟹ i ∉ pdevs_domain y ⟹ e i *⇩R pdevs_apply x i = 0"
  shows "pdevs_val e x = pdevs_val f y"
  using assms
  by (force simp: pdevs_val_pdevs_domain
    intro!:
      sum.reindex_bij_witness_not_neutral[where
        i=id and j = id and
        S'="pdevs_domain x - pdevs_domain y" and
        T'="pdevs_domain y - pdevs_domain x"])

definition
  filter_pdevs_raw::"(nat ⇒ 'a ⇒ bool) ⇒ (nat ⇒ 'a::real_vector) ⇒ (nat ⇒ 'a)"
  where "filter_pdevs_raw I X = (λi. if I i (X i) then X i else 0)"

lemma filter_pdevs_raw_nonzeros: "{i. filter_pdevs_raw s f i ≠ 0} = {i. f i ≠ 0} ∩ {x. s x (f x)}"
  by (auto simp: filter_pdevs_raw_def)

lift_definition filter_pdevs::"(nat ⇒ 'a ⇒ bool) ⇒ 'a::real_vector pdevs ⇒ 'a pdevs"
  is filter_pdevs_raw
  by (simp add: filter_pdevs_raw_nonzeros)

lemma pdevs_apply_filter_pdevs[simp]:
  "pdevs_apply (filter_pdevs I x) i = (if I i (pdevs_apply x i) then pdevs_apply x i else 0)"
  by transfer (auto simp: filter_pdevs_raw_def)

lemma degree_filter_pdevs_le: "degree (filter_pdevs I x) ≤ degree x"
  by (rule degree_leI) (simp split: if_split_asm)

lemma pdevs_val_filter_pdevs:
  "pdevs_val e (filter_pdevs I x) =
    (∑i ∈ {..<degree x} ∩ {i. I i (pdevs_apply x i)}. e i *⇩R pdevs_apply x i)"
  by (auto simp: pdevs_val_sum if_distrib sum.inter_restrict degree_filter_pdevs_le degree_gt
    intro!: sum.mono_neutral_cong_left split: if_split_asm)

lemma pdevs_val_filter_pdevs_dom:
  "pdevs_val e (filter_pdevs I x) =
    (∑i ∈ pdevs_domain x ∩ {i. I i (pdevs_apply x i)}. e i *⇩R pdevs_apply x i)"
  by (auto
    simp: pdevs_val_pdevs_domain if_distrib sum.inter_restrict degree_filter_pdevs_le degree_gt
    intro!: sum.mono_neutral_cong_left split: if_split_asm)

lemma pdevs_val_filter_pdevs_eval:
  "pdevs_val e (filter_pdevs p x) = pdevs_val (λi. if p i (pdevs_apply x i) then e i else 0) x"
  by (auto split: if_split_asm intro!: pdevs_val_eqI)

definition "pdevs_applys X i = map (λx. pdevs_apply x i) X"
definition "pdevs_vals e X = map (pdevs_val e) X"
definition "aform_vals e X = map (aform_val e) X"
definition "filter_pdevs_list I X = map (filter_pdevs (λi _. I i (pdevs_applys X i))) X"

lemma pdevs_applys_filter_pdevs_list[simp]:
  "pdevs_applys (filter_pdevs_list I X) i = (if I i (pdevs_applys X i) then pdevs_applys X i else
    map (λ_. 0) X)"
  by (auto simp: filter_pdevs_list_def o_def pdevs_applys_def)

definition "degrees X = Max (insert 0 (degree ` set X))"

abbreviation "degree_aforms X ≡ degrees (map snd X)"

lemma degrees_leI:
  assumes "⋀x. x ∈ set X ⟹ degree x ≤ K"
  shows "degrees X ≤ K"
  using assms
  by (auto simp: degrees_def intro!: Max.boundedI)

lemma degrees_leD:
  assumes "degrees X ≤ K"
  shows "⋀x. x ∈ set X ⟹ degree x ≤ K"
  using assms
  by (auto simp: degrees_def intro!: Max.boundedI)

lemma degree_filter_pdevs_list_le: "degrees (filter_pdevs_list I x) ≤ degrees x"
  by (rule degrees_leI) (auto simp: filter_pdevs_list_def intro!: degree_le dest!: degrees_leD)


definition "dense_list_of_pdevs x = map (λi. pdevs_apply x i) [0..<degree x]"

subsubsection ‹(reverse) ordered coefficients as list›

definition "list_of_pdevs x =
  map (λi. (i, pdevs_apply x i)) (rev (sorted_list_of_set (pdevs_domain x)))"

lemma list_of_pdevs_zero_pdevs[simp]: "list_of_pdevs zero_pdevs = []"
  by (auto simp: list_of_pdevs_def)

lemma sum_list_list_of_pdevs: "sum_list (map snd (list_of_pdevs x)) = sum_list (dense_list_of_pdevs x)"
  by (auto intro!: sum.mono_neutral_cong_left
    simp add: degree_gt sum_list_distinct_conv_sum_set dense_list_of_pdevs_def list_of_pdevs_def)

lemma sum_list_filter_dense_list_of_pdevs[symmetric]:
  "sum_list (map snd (filter (p o snd) (list_of_pdevs x))) =
    sum_list (filter p (dense_list_of_pdevs x))"
  by (auto intro!: sum.mono_neutral_cong_left
    simp add: degree_gt sum_list_distinct_conv_sum_set dense_list_of_pdevs_def list_of_pdevs_def
      o_def filter_map)

lemma pdevs_of_list_dense_list_of_pdevs: "pdevs_of_list (dense_list_of_pdevs x) = x"
  by (auto simp: pdevs_apply_pdevs_of_list dense_list_of_pdevs_def pdevs_eqI)

lemma pdevs_val_sum_list: "pdevs_val (λ_. c) X = c *⇩R sum_list (map snd (list_of_pdevs X))"
  by (auto simp: pdevs_val_sum sum_list_list_of_pdevs pdevs_val_const_pdevs_of_list[symmetric]
    pdevs_of_list_dense_list_of_pdevs)

lemma list_of_pdevs_all_nonzero: "list_all (λx. x ≠ 0) (map snd (list_of_pdevs xs))"
  by (auto simp: list_of_pdevs_def list_all_iff)

lemma list_of_pdevs_nonzero: "x ∈ set (map snd (list_of_pdevs xs)) ⟹ x ≠ 0"
  by (auto simp: list_of_pdevs_def)

lemma pdevs_of_list_scaleR_0[simp]:
  fixes xs::"'a::real_vector list"
  shows "pdevs_of_list (map ((*⇩R) 0) xs) = zero_pdevs"
  by (auto simp: pdevs_apply_pdevs_of_list intro!: pdevs_eqI)

lemma degree_pdevs_of_list_scaleR:
  "degree (pdevs_of_list (map ((*⇩R) c) xs)) = (if c ≠ 0 then degree (pdevs_of_list xs) else 0)"
  by (auto simp: pdevs_apply_pdevs_of_list intro!: degree_cong)

lemma list_of_pdevs_eq:
  "rev (list_of_pdevs X) = (filter ((≠) 0 o snd) (map (λi. (i, pdevs_apply X i)) [0..<degree X]))"
  (is "_ = filter ?P (map ?f ?xs)")
  using map_filter[of ?f ?P ?xs]
  by (auto simp: list_of_pdevs_def o_def sorted_list_of_pdevs_domain_eq rev_map)

lemma sum_list_take_pdevs_val_eq:
  "sum_list (take d xs) = pdevs_val (λi. if i < d then 1 else 0) (pdevs_of_list xs)"
proof -
  have "sum_list (take d xs) = 1 *⇩R sum_list (take d xs)" by simp
  also note pdevs_val_const_pdevs_of_list[symmetric]
  also have "pdevs_val (λ_. 1) (pdevs_of_list (take d xs)) =
      pdevs_val (λi. if i < d then 1 else 0) (pdevs_of_list xs)"
    by (auto simp: pdevs_apply_pdevs_of_list split: if_split_asm intro!: pdevs_val_eqI)
  finally show ?thesis .
qed

lemma zero_in_range_pdevs_apply[intro, simp]:
  fixes X::"'a::real_vector pdevs" shows "0 ∈ range (pdevs_apply X)"
  by (metis degree_gt less_irrefl rangeI)

lemma dense_list_in_range: "x ∈ set (dense_list_of_pdevs X) ⟹ x ∈ range (pdevs_apply X)"
  by (auto simp: dense_list_of_pdevs_def)

lemma not_in_dense_list_zeroD:
  assumes "pdevs_apply X i ∉ set (dense_list_of_pdevs X)"
  shows "pdevs_apply X i = 0"
proof (rule ccontr)
  assume "pdevs_apply X i ≠ 0"
  hence "i < degree X"
    by (rule degree_gt)
  thus False using assms
    by (auto simp: dense_list_of_pdevs_def)
qed

lemma list_all_list_of_pdevsI:
  assumes "⋀i. i ∈ pdevs_domain X ⟹ P (pdevs_apply X i)"
  shows "list_all (λx. P x) (map snd (list_of_pdevs X))"
  using assms by (auto simp: list_all_iff list_of_pdevs_def)

lemma pdevs_of_list_map_scaleR:
  "pdevs_of_list (map (scaleR r) xs) = scaleR_pdevs r (pdevs_of_list xs)"
  by (auto intro!: pdevs_eqI simp: pdevs_apply_pdevs_of_list)

lemma
  map_permI:
  assumes "xs <~~> ys"
  shows "map f xs <~~> map f ys"
  using assms by induct auto

lemma rev_perm: "rev xs <~~> ys ⟷ xs <~~> ys"
  by simp

lemma list_of_pdevs_perm_filter_nonzero:
  "map snd (list_of_pdevs X) <~~> (filter ((≠) 0) (dense_list_of_pdevs X))"
proof -
  have zip_map:
    "zip [0..<degree X] (dense_list_of_pdevs X) = map (λi. (i, pdevs_apply X i)) [0..<degree X]"
    by (auto simp: dense_list_of_pdevs_def intro!: nth_equalityI)
  have "rev (list_of_pdevs X) <~~>
      filter ((≠) 0 o snd) (zip [0..<degree X] (dense_list_of_pdevs X))"
    by (auto simp: list_of_pdevs_eq o_def zip_map)
  from map_permI[OF this, of snd]
  have "map snd (list_of_pdevs X) <~~>
      map snd (filter ((≠) 0 ∘ snd) (zip [0..<degree X] (dense_list_of_pdevs X)))"
    by (simp add: rev_map[symmetric] rev_perm)
  also have "map snd (filter ((≠) 0 ∘ snd) (zip [0..<degree X] (dense_list_of_pdevs X))) =
      filter ((≠) 0) (dense_list_of_pdevs X)"
    using map_filter[of snd "(≠) 0" "(zip [0..<degree X] (dense_list_of_pdevs X))"]
    by (simp add: o_def dense_list_of_pdevs_def)
   finally
   show ?thesis .
qed

lemma pdevs_val_filter:
  assumes mem: "e ∈ UNIV → I"
  assumes "0 ∈ I"
  obtains e' where
    "pdevs_val e (pdevs_of_list (filter p xs)) = pdevs_val e' (pdevs_of_list xs)"
    "e' ∈ UNIV → I"
  unfolding pdevs_val_filter_pdevs_eval
proof -
  have "(λ_::nat. 0) ∈ UNIV → I" using assms by simp
  have "pdevs_val e (pdevs_of_list (filter p xs)) =
      pdevs_val e (pdevs_of_list (filter p xs)) +
      pdevs_val (λ_. 0) (pdevs_of_list (filter (Not o p) xs))"
    by (simp add: pdevs_val_sum)
  also
  from pdevs_val_pdevs_of_list_append[OF ‹e ∈ _› ‹(λ_. 0) ∈ _›]
  obtain e' where "e' ∈ UNIV → I"
      "… = pdevs_val e' (pdevs_of_list (filter p xs @ filter (Not o p) xs))"
    by metis
  note this(2)
  also
  from pdevs_val_perm[OF partition_permI ‹e' ∈ _›]
  obtain e'' where "… = pdevs_val e'' (pdevs_of_list xs)" "e'' ∈ UNIV → I" by metis
  note this(1)
  finally show ?thesis using ‹e'' ∈ _› ..
qed

lemma
  pdevs_val_of_list_of_pdevs:
  assumes "e ∈ UNIV → I"
  assumes "0 ∈ I"
  obtains e' where
    "pdevs_val e (pdevs_of_list (map snd (list_of_pdevs X))) = pdevs_val e' X"
    "e' ∈ UNIV → I"
proof -
  obtain e' where "e' ∈ UNIV → I"
    and "pdevs_val e (pdevs_of_list (map snd (list_of_pdevs X))) =
      pdevs_val e' (pdevs_of_list (filter ((≠) 0) (dense_list_of_pdevs X)))"
    by (rule pdevs_val_perm[OF list_of_pdevs_perm_filter_nonzero assms(1)])
  note this(2)
  also from pdevs_val_filter[OF ‹e' ∈ _› ‹0 ∈ I›, of "(≠) 0" "dense_list_of_pdevs X"]
  obtain e'' where "e'' ∈ UNIV → I"
    and "… = pdevs_val e'' (pdevs_of_list (dense_list_of_pdevs X))"
    by metis
  note this(2)
  also have "… = pdevs_val e'' X" by (simp add: pdevs_of_list_dense_list_of_pdevs)
  finally show ?thesis using ‹e'' ∈ UNIV → I› ..
qed

lemma
  pdevs_val_of_list_of_pdevs2:
  assumes "e ∈ UNIV → I"
  obtains e' where
    "pdevs_val e X = pdevs_val e' (pdevs_of_list (map snd (list_of_pdevs X)))"
    "e' ∈ UNIV → I"
proof -
  from list_of_pdevs_perm_filter_nonzero[of X]
  have perm: "(filter ((≠) 0) (dense_list_of_pdevs X)) <~~> map snd (list_of_pdevs X)"
    by simp
  have "pdevs_val e X = pdevs_val e (pdevs_of_list (dense_list_of_pdevs X))"
    by (simp add: pdevs_of_list_dense_list_of_pdevs)
  also from pdevs_val_partition[OF ‹e ∈ _›, of "dense_list_of_pdevs X" "(≠) 0"]
  obtain f g where "f ∈ UNIV → I" "g ∈ UNIV → I"
    "… = pdevs_val f (pdevs_of_list (filter ((≠) 0) (dense_list_of_pdevs X))) +
      pdevs_val g (pdevs_of_list (filter (Not ∘ (≠) 0) (dense_list_of_pdevs X)))"
    (is "_ = ?f + ?g")
    by metis
  note this(3)
  also
  have "pdevs_of_list [x←dense_list_of_pdevs X . x = 0] = zero_pdevs"
    by (auto intro!: pdevs_eqI simp: pdevs_apply_pdevs_of_list dest!: nth_mem)
  hence "?g = 0" by (auto simp: o_def )
  also
  obtain e' where "e' ∈ UNIV → I"
    and "?f = pdevs_val e' (pdevs_of_list (map snd (list_of_pdevs X)))"
    by (rule pdevs_val_perm[OF perm ‹f ∈ _›])
  note this(2)
  finally show ?thesis using ‹e' ∈ UNIV → I› by (auto intro!: that)
qed

lemma dense_list_of_pdevs_scaleR:
  "r ≠ 0 ⟹ map ((*⇩R) r) (dense_list_of_pdevs x) = dense_list_of_pdevs (scaleR_pdevs r x)"
  by (auto simp: dense_list_of_pdevs_def)

lemma degree_pdevs_of_list_eq:
  "(⋀x. x ∈ set xs ⟹ x ≠ 0) ⟹ degree (pdevs_of_list xs) = length xs"
  by (cases xs) (auto simp add: pdevs_apply_pdevs_of_list nth_Cons
    intro!: degree_eqI
    split: nat.split)

lemma dense_list_of_pdevs_pdevs_of_list:
  "(⋀x. x ∈ set xs ⟹ x ≠ 0) ⟹ dense_list_of_pdevs (pdevs_of_list xs) = xs"
  by (auto simp: dense_list_of_pdevs_def degree_pdevs_of_list_eq pdevs_apply_pdevs_of_list
    intro!: nth_equalityI)

lemma pdevs_of_list_sum:
  assumes "distinct xs"
  assumes "e ∈ UNIV → I"
  obtains f where "f ∈ UNIV → I" "pdevs_val e (pdevs_of_list xs) = (∑P∈set xs. f P *⇩R P)"
proof -
  define f where "f X = e (the (map_of (zip xs [0..<length xs]) X))" for X
  from assms have "f ∈ UNIV → I"
    by (auto simp: f_def)
  moreover
  have "pdevs_val e (pdevs_of_list xs) = (∑P∈set xs. f P *⇩R P)"
    by (auto simp add: pdevs_val_zip f_def assms sum_list_distinct_conv_sum_set[symmetric]
      in_set_zip map_of_zip_upto2_length_eq_nth
      intro!: sum_list_nth_eqI)
  ultimately show ?thesis ..
qed

lemma pdevs_domain_eq_pdevs_of_list:
  assumes nz: "⋀x. x ∈ set (xs) ⟹ x ≠ 0"
  shows "pdevs_domain (pdevs_of_list xs) = {0..<length xs}"
  using nz
  by (auto simp: pdevs_apply_pdevs_of_list split: if_split_asm)

lemma length_list_of_pdevs_pdevs_of_list:
  assumes nz: "⋀x. x ∈ set xs ⟹ x ≠ 0"
  shows "length (list_of_pdevs (pdevs_of_list xs)) = length xs"
  using nz by (auto simp: list_of_pdevs_def pdevs_domain_eq_pdevs_of_list)

lemma nth_list_of_pdevs_pdevs_of_list:
  assumes nz: "⋀x. x ∈ set xs ⟹ x ≠ 0"
  assumes l: "n < length xs"
  shows "list_of_pdevs (pdevs_of_list xs) ! n  = ((length xs - Suc n), xs ! (length xs - Suc n))"
  using nz l
  by (auto simp: list_of_pdevs_def pdevs_domain_eq_pdevs_of_list rev_nth pdevs_apply_pdevs_of_list)

lemma list_of_pdevs_pdevs_of_list_eq:
  "(⋀x. x ∈ set xs ⟹ x ≠ 0) ⟹
    list_of_pdevs (pdevs_of_list xs) = zip (rev [0..<length xs]) (rev xs)"
  by (auto simp: nth_list_of_pdevs_pdevs_of_list length_list_of_pdevs_pdevs_of_list rev_nth
    intro!: nth_equalityI)

lemma sum_list_filter_list_of_pdevs_of_list:
  fixes xs::"'a::comm_monoid_add list"
  assumes "⋀x. x ∈ set xs ⟹ x ≠ 0"
  shows "sum_list (filter p (map snd (list_of_pdevs (pdevs_of_list xs)))) = sum_list (filter p xs)"
  using assms
  by (auto simp: list_of_pdevs_pdevs_of_list_eq rev_filter[symmetric])

lemma
  sum_list_partition:
  fixes xs::"'a::comm_monoid_add list"
  shows "sum_list (filter p xs) + sum_list (filter (Not o p) xs) = sum_list xs"
  by (induct xs) (auto simp: ac_simps)


subsection ‹2d zonotopes›

definition "prod_of_pdevs x y = binop_pdevs Pair x y"

lemma apply_pdevs_prod_of_pdevs[simp]:
  "pdevs_apply (prod_of_pdevs x y) i = (pdevs_apply x i, pdevs_apply y i)"
  unfolding prod_of_pdevs_def
  by (simp add: zero_prod_def)

lemma pdevs_domain_prod_of_pdevs[simp]:
  "pdevs_domain (prod_of_pdevs x y) = pdevs_domain x ∪ pdevs_domain y"
  by (auto simp: zero_prod_def)

lemma pdevs_val_prod_of_pdevs[simp]:
  "pdevs_val e (prod_of_pdevs x y) = (pdevs_val e x, pdevs_val e y)"
proof -
  have "pdevs_val e x = (∑i∈pdevs_domain x ∪ pdevs_domain y. e i *⇩R pdevs_apply x i)"
    (is "_ = ?x")
    unfolding pdevs_val_pdevs_domain
    by (rule sum.mono_neutral_cong_left) auto
  moreover have "pdevs_val e y = (∑i∈pdevs_domain x ∪ pdevs_domain y. e i *⇩R pdevs_apply y i)"
    (is "_ = ?y")
    unfolding pdevs_val_pdevs_domain
    by (rule sum.mono_neutral_cong_left) auto
  ultimately have "(pdevs_val e x, pdevs_val e y) = (?x, ?y)"
    by auto
  also have "… = pdevs_val e (prod_of_pdevs x y)"
    by (simp add: sum_prod pdevs_val_pdevs_domain)
  finally show ?thesis by simp
qed

definition prod_of_aforms (infixr "×⇩a" 80)
  where "prod_of_aforms x y = ((fst x, fst y), prod_of_pdevs (snd x) (snd y))"


subsection ‹Intervals›

definition One_pdevs_raw::"nat ⇒ 'a::executable_euclidean_space"
  where "One_pdevs_raw i = (if i < length (Basis_list::'a list) then Basis_list ! i else 0)"

lemma zeros_One_pdevs_raw:
  "One_pdevs_raw -` {0::'a::executable_euclidean_space} = {length (Basis_list::'a list)..}"
  by (auto simp: One_pdevs_raw_def nonzero_Basis split: if_split_asm dest!: nth_mem)

lemma nonzeros_One_pdevs_raw:
  "{i. One_pdevs_raw i ≠ (0::'a::executable_euclidean_space)} = - {length (Basis_list::'a list)..}"
  using zeros_One_pdevs_raw
  by blast

lift_definition One_pdevs::"'a::executable_euclidean_space pdevs" is One_pdevs_raw
  by (auto simp: nonzeros_One_pdevs_raw)

lemma pdevs_apply_One_pdevs[simp]: "pdevs_apply One_pdevs i =
  (if i < length (Basis_list::'a::executable_euclidean_space list) then Basis_list ! i else 0::'a)"
  by transfer (simp add: One_pdevs_raw_def)

lemma Max_Collect_less_nat: "Max {i::nat. i < k} = (if k = 0 then Max {} else k - 1)"
  by (auto intro!: Max_eqI)

lemma degree_One_pdevs[simp]: "degree (One_pdevs::'a pdevs) =
    length (Basis_list::'a::executable_euclidean_space list)"
  by (auto simp: degree_eq_Suc_max Basis_list_nth_nonzero Max_Collect_less_nat
      intro!: Max_eqI DIM_positive)

definition inner_scaleR_pdevs::"'a::euclidean_space ⇒ 'a pdevs ⇒ 'a pdevs"
  where "inner_scaleR_pdevs b x = unop_pdevs (λx. (b ∙ x) *⇩R x) x"

lemma pdevs_apply_inner_scaleR_pdevs[simp]:
  "pdevs_apply (inner_scaleR_pdevs a x) i = (a ∙ (pdevs_apply x i)) *⇩R (pdevs_apply x i)"
  by (simp add: inner_scaleR_pdevs_def)

lemma degree_inner_scaleR_pdevs_le:
  "degree (inner_scaleR_pdevs (l::'a::executable_euclidean_space) One_pdevs) ≤
    degree (One_pdevs::'a pdevs)"
  by (rule degree_leI) (auto simp: inner_scaleR_pdevs_def One_pdevs_raw_def)

definition "pdevs_of_ivl l u = scaleR_pdevs (1/2) (inner_scaleR_pdevs (u - l) One_pdevs)"

lemma degree_pdevs_of_ivl_le:
  "degree (pdevs_of_ivl l u::'a::executable_euclidean_space pdevs) ≤ DIM('a)"
  using degree_inner_scaleR_pdevs_le
  by (simp add: pdevs_of_ivl_def)

lemma pdevs_apply_pdevs_of_ivl:
  defines "B ≡ Basis_list::'a::executable_euclidean_space list"
  shows "pdevs_apply (pdevs_of_ivl l u) i = (if i < length B then ((u - l)∙(B!i)/2)*⇩R(B!i) else 0)"
  by (auto simp: pdevs_of_ivl_def B_def)

lemma deg_length_less_imp[simp]:
  "k < degree (pdevs_of_ivl l u::'a::executable_euclidean_space pdevs) ⟹
    k < length (Basis_list::'a list)"
  by (metis (no_types, opaque_lifting) degree_One_pdevs degree_inner_scaleR_pdevs_le degree_scaleR_pdevs
      dual_order.strict_trans length_Basis_list_pos nat_neq_iff not_le pdevs_of_ivl_def)

lemma tdev_pdevs_of_ivl: "tdev (pdevs_of_ivl l u) = ¦u - l¦ /⇩R 2"
proof -
  have "tdev (pdevs_of_ivl l u) =
    (∑i <degree (pdevs_of_ivl l u). ¦pdevs_apply (pdevs_of_ivl l u) i¦)"
    by (auto simp: tdev_def)
  also have "… = (∑i = 0..<length (Basis_list::'a list). ¦pdevs_apply (pdevs_of_ivl l u) i¦)"
    using degree_pdevs_of_ivl_le[of l u]
    by (intro sum.mono_neutral_cong_left) auto
  also have "… = (∑i = 0..<length (Basis_list::'a list).
      ¦((u - l) ∙ Basis_list ! i / 2) *⇩R Basis_list ! i¦)"
    by (auto simp: pdevs_apply_pdevs_of_ivl)
  also have "… = (∑b ← Basis_list. ¦((u - l) ∙ b / 2) *⇩R b¦)"
    by (auto simp: sum_list_sum_nth)
  also have "… = (∑b∈Basis. ¦((u - l) ∙ b / 2) *⇩R b¦)"
    by (auto simp: sum_list_distinct_conv_sum_set)
  also have "… = ¦u - l¦ /⇩R 2"
    by (subst euclidean_representation[symmetric, of "¦u - l¦ /⇩R 2"])
      (simp add:  abs_inner abs_scaleR)
  finally show ?thesis .
qed

definition "aform_of_ivl l u = ((l + u)/⇩R2, pdevs_of_ivl l u)"

definition "aform_of_point x = aform_of_ivl x x"

lemma Elem_affine_of_ivl_le:
  assumes "e ∈ UNIV → {-1 .. 1}"
  assumes "l ≤ u"
  shows "l ≤ aform_val e (aform_of_ivl l u)"
proof -
  have "l =  (1 / 2) *⇩R l + (1 / 2) *⇩R l"
    by (simp add: scaleR_left_distrib[symmetric])
  also have "… = (l + u)/⇩R2 - tdev (pdevs_of_ivl l u)"
    by (auto simp: assms tdev_pdevs_of_ivl algebra_simps)
  also have "… ≤ aform_val e (aform_of_ivl l u)"
    using abs_pdevs_val_le_tdev[OF assms(1), of "pdevs_of_ivl l u"]
    by (auto simp: aform_val_def aform_of_ivl_def minus_le_iff dest!: abs_le_D2)
  finally show ?thesis .
qed

lemma Elem_affine_of_ivl_ge:
  assumes "e ∈ UNIV → {-1 .. 1}"
  assumes "l ≤ u"
  shows "aform_val e (aform_of_ivl l u) ≤ u"
proof -
  have "aform_val e (aform_of_ivl l u) ≤  (l + u)/⇩R2 + tdev (pdevs_of_ivl l u)"
    using abs_pdevs_val_le_tdev[OF assms(1), of "pdevs_of_ivl l u"]
    by (auto simp: aform_val_def aform_of_ivl_def minus_le_iff dest!: abs_le_D1)
  also have "… = (1 / 2) *⇩R u + (1 / 2) *⇩R u"
    by (auto simp: assms tdev_pdevs_of_ivl algebra_simps)
  also have "… = u"
    by (simp add: scaleR_left_distrib[symmetric])
  finally show ?thesis .
qed

lemma
  map_of_zip_upto_length_eq_nth:
  assumes "i < length B"
  assumes "d = length B"
  shows "(map_of (zip [0..<d] B) i) = Some (B ! i)"
proof -
  have "length [0..<length B] = length B"
    by simp
  from map_of_zip_is_Some[OF this, of i] assms
  have "map_of (zip [0..<length B] B) i = Some (B ! i)"
    by (auto simp: in_set_zip)
  thus ?thesis by (simp add: assms)
qed

lemma in_ivl_affine_of_ivlE:
  assumes "k ∈ {l .. u}"
  obtains e where "e ∈ UNIV → {-1 .. 1}" "k = aform_val e (aform_of_ivl l u)"
proof atomize_elim
  define e where [abs_def]: "e i = (let b = if i <length (Basis_list::'a list) then
    (the (map_of (zip [0..<length (Basis_list::'a list)] (Basis_list::'a list)) i)) else 0 in
      ((k - (l + u) /⇩R 2) ∙ b) / (((u - l) /⇩R 2) ∙ b))" for i
  let ?B = "Basis_list::'a list"

  have "k = (1 / 2) *⇩R (l + u) +
      (∑b ∈ Basis. (if (u - l) ∙ b = 0 then 0 else ((k - (1 / 2) *⇩R (l + u)) ∙ b)) *⇩R b)"
    (is "_ = _ + ?dots")
    using assms
    by (force simp add: algebra_simps eucl_le[where 'a='a] intro!: euclidean_eqI[where 'a='a])
  also have
    "?dots = (∑b ∈ Basis. (if (u - l) ∙ b = 0 then 0 else ((k - (1 / 2) *⇩R (l + u)) ∙ b) *⇩R b))"
    by (auto intro!: sum.cong)
  also have "… = (∑b ← ?B. (if (u - l) ∙ b = 0 then 0 else ((k - (1 / 2) *⇩R (l + u)) ∙ b) *⇩R b))"
    by (auto simp: sum_list_distinct_conv_sum_set)
  also have "… =
    (∑i = 0..<length ?B.
        (if (u - l) ∙ ?B ! i = 0 then 0 else ((k - (1 / 2) *⇩R (l + u)) ∙ ?B ! i) *⇩R ?B ! i))"
    by (auto simp: sum_list_sum_nth)
  also have "… =
    (∑i = 0..<degree (inner_scaleR_pdevs (u - l) One_pdevs).
        (if (u - l) ∙ Basis_list ! i = 0 then 0
        else ((k - (1 / 2) *⇩R (l + u)) ∙ Basis_list ! i) *⇩R Basis_list ! i))"
    using degree_inner_scaleR_pdevs_le[of "u - l"]
    by (intro sum.mono_neutral_cong_right) (auto dest!: degree)
  also have "(1 / 2) *⇩R (l + u) +
    (∑i = 0..<degree (inner_scaleR_pdevs (u - l) One_pdevs).
        (if (u - l) ∙ Basis_list ! i = 0 then 0
        else ((k - (1 / 2) *⇩R (l + u)) ∙ Basis_list ! i) *⇩R Basis_list ! i)) =
      aform_val e (aform_of_ivl l u)"
    using degree_inner_scaleR_pdevs_le[of "u - l"]
    by (auto simp: aform_val_def aform_of_ivl_def pdevs_of_ivl_def map_of_zip_upto_length_eq_nth
      e_def Let_def pdevs_val_sum
      intro!: sum.cong)
  finally have "k = aform_val e (aform_of_ivl l u)" .

  moreover
  {
    fix k l u::real assume *: "l ≤ k" "k ≤ u"
    let ?m = "l / 2 + u / 2"
    have "¦k - ?m¦ ≤ ¦if k ≤ ?m then ?m - l else u - ?m¦"
      using * by auto
    also have "… ≤ ¦u / 2 - l / 2¦"
      by (auto simp: abs_real_def)
    finally have "¦k - (l / 2 + u / 2)¦ ≤ ¦u / 2 - l/2¦" .
  } note midpoint_abs = this
  have "e ∈ UNIV → {- 1..1}"
    using assms
    unfolding e_def Let_def
    by (intro Pi_I divide_atLeastAtMost_1_absI)
      (auto simp: map_of_zip_upto_length_eq_nth eucl_le[where 'a='a]
        divide_le_eq_1 not_less inner_Basis algebra_simps intro!: midpoint_abs
        dest!: nth_mem)
  ultimately show "∃e. e ∈ UNIV → {- 1..1} ∧ k = aform_val e (aform_of_ivl l u)"
    by blast
qed

lemma Inf_aform_aform_of_ivl:
  assumes "l ≤ u"
  shows "Inf_aform (aform_of_ivl l u) = l"
  using assms
  by (auto simp: Inf_aform_def aform_of_ivl_def tdev_pdevs_of_ivl abs_diff_eq1 algebra_simps)
    (metis field_sum_of_halves scaleR_add_left scaleR_one)

lemma Sup_aform_aform_of_ivl:
  assumes "l ≤ u"
  shows "Sup_aform (aform_of_ivl l u) = u"
  using assms
  by (auto simp: Sup_aform_def aform_of_ivl_def tdev_pdevs_of_ivl abs_diff_eq1 algebra_simps)
    (metis field_sum_of_halves scaleR_add_left scaleR_one)

lemma Affine_aform_of_ivl:
  "a ≤ b ⟹ Affine (aform_of_ivl a b) = {a .. b}"
  by (force simp: Affine_def valuate_def intro!: Elem_affine_of_ivl_ge Elem_affine_of_ivl_le
    elim!: in_ivl_affine_of_ivlE)

end