Theory IL_Interval

(*  Title:      IL_Interval.thy
    Date:       Oct 2006
    Author:     David Trachtenherz
*)

section ‹Intervals and operations for temporal logic declarations›

theory IL_Interval
imports 
  "List-Infinite.InfiniteSet2"
  "List-Infinite.SetIntervalStep"
begin

subsection ‹Time intervals -- definitions and basic lemmata›

subsubsection ‹Definitions›

type_synonym Time = nat

(* Time interval *)
type_synonym iT = "Time set"

text ‹Infinite interval starting at some natural @{term "n"}.›
definition 
  iFROM :: "Time  iT" ("[_…]") (* [n, ∞) *) 
where
  "[n…]  {n..}"

text ‹Finite interval starting at @{term "0"} and ending at some natural @{term "n"}.›
definition
  iTILL :: "Time  iT" ("[…_]") (* [0, n] *) (* Equivalent to [0…,n] *)
where
  "[…n]  {..n}"

text ‹
  Finite bounded interval containing the naturals between 
  @{term "n"} and @{term "n + d"}.
  @{term "d"} denotes the difference between left and right interval bound.
  The number of elements is @{term "d + 1"} so that an empty interval cannot be defined.›
definition
  iIN   :: "Time  nat  iT" ( "[_…,_]") (* [n, n+d] *)
where
  "[n…,d]  {n..n+d}"



text ‹
  Infinite modulo interval containing all naturals
  having the same division remainder modulo @{term "m"}
  as @{term "r"}, and beginning at @{term "n"}.›
definition
  iMOD  :: "Time  nat  iT" ( "[ _, mod _ ]" ) 
where
  "[r, mod m]  { x. x mod m = r mod m  r  x}" 


text ‹
  Finite bounded modulo interval containing all naturals
  having the same division remainder modulo @{term "m"}
  as @{term "r"}, beginning at @{term "n"},
  and ending after @{term "c"} cycles at @{term "r + m * c"}.
  The number of elements is @{term "c + 1"} so that an empty interval cannot be defined.›
definition
  iMODb :: "Time  nat  nat  iT" ( "[ _, mod _, _ ]" ) 
where
  "[r, mod m, c]  { x. x mod m = r mod m  r  x  x  r + m * c}"

subsubsection ‹Membership in an interval›

lemmas iT_defs = iFROM_def iTILL_def iIN_def iMOD_def iMODb_def

lemma iFROM_iff: "x  [n…] = (n  x)"
by (simp add: iFROM_def)
lemma iTILL_iff: "x  […n] = (x  n)"
by (simp add: iTILL_def)
lemma iIN_iff:"x  [n…,d] = (n  x  x  n + d)"
by (simp add: iIN_def)
lemma iMOD_iff: "x  [r, mod m] = (x mod m = r mod m  r  x)"
by (simp add: iMOD_def)
lemma iMODb_iff: "x  [r, mod m, c] = 
  (x mod m = r mod m  r  x  x  r + m * c)"
by (simp add: iMODb_def)

lemma iFROM_D: "x  [n…]  (n  x)"
by (rule iFROM_iff[THEN iffD1])
lemma iTILL_D: "x  […n]  (x  n)"
by (rule iTILL_iff[THEN iffD1])
corollary iIN_geD: "x  [n…,d]  n  x"
by (simp add: iIN_iff)
corollary iIN_leD: "x  [n…,d]  x  n + d"
by (simp add: iIN_iff)
corollary iMOD_modD: "x  [r, mod m]  x mod m = r mod m"
by (simp add: iMOD_iff)
corollary iMOD_geD: "x  [r, mod m]  r  x"
by (simp add: iMOD_iff)
corollary iMODb_modD: "x  [r, mod m, c]  x mod m = r mod m"
by (simp add: iMODb_iff)
corollary iMODb_geD: "x  [r, mod m, c]  r  x"
by (simp add: iMODb_iff)
corollary iMODb_leD: "x  [r, mod m, c]  x  r + m * c"
by (simp add: iMODb_iff)

lemmas iT_iff = iFROM_iff iTILL_iff iIN_iff iMOD_iff iMODb_iff

lemmas iT_drule =
  iFROM_D
  iTILL_D
  iIN_geD iIN_leD
  iMOD_modD iMOD_geD
  iMODb_modD iMODb_geD iMODb_leD

lemma 
  iFROM_I [intro]: "n  x  x  [n…]" and
  iTILL_I [intro]: "x  n  x  […n]" and
  iIN_I [intro]:   "n  x  x  n + d  x  [n…,d]" and
  iMOD_I [intro]:  "x mod m = r mod m  r  x  x  [r, mod m]" and
  iMODb_I [intro]: "x mod m = r mod m  r  x  x  r + m * c  x  [r, mod m, c]"
by (simp add: iT_iff)+

lemma 
  iFROM_E [elim]:  "x  [n…]  (n  x  P)  P" and 
  iTILL_E [elim]:  "x  […n]  (x  n  P)  P" and 
  iIN_E [elim]:    "x  [n…,d]  (n  x  x  n + d  P)  P" and 
  iMOD_E [elim]:   "x  [r, mod m]  (x mod m = r mod m  r  x  P)  P" and 
  iMODb_E [elim]:   "x  [r, mod m, c]  (x mod m = r mod m  r  x  x  r + m * c  P)  P"
by (simp add: iT_iff)+

(*
lemma "0 < n ⟹ ∃x ∈ [n…,2*n]. x mod 2 = 0"
apply (simp add: iT_defs)
apply (rule_tac x="2*n" in bexI)
apply simp
apply simp
done
lemma "0 < n ⟹ ∃x ∈ [n…,2*n]. x mod 2 = 0"
apply (simp add: iT_defs atLeastAtMost_def atLeast_def atMost_def Collect_conj_eq[symmetric])
apply (rule_tac x="2*n" in exI)
apply simp
done
*)



lemma iIN_Suc_insert_conv: "
  insert (Suc (n + d)) [n…,d] = [n…,Suc d]"
by (fastforce simp: iIN_iff)

lemma iTILL_Suc_insert_conv: "insert (Suc n) […n] = […Suc n]"
by (fastforce simp: iIN_Suc_insert_conv[of 0 n])

lemma iMODb_Suc_insert_conv: "
  insert (r + m * Suc c) [r, mod m, c] = [r, mod m, Suc c]"
apply (rule set_eqI)
apply (simp add: iMODb_iff add.commute[of _ r])
apply (simp add: add.commute[of m])
apply (simp add: add.assoc[symmetric])
apply (rule iffI)
 apply fastforce
apply (elim conjE)
apply (drule_tac x=x in order_le_less[THEN iffD1, rule_format])
apply (erule disjE)
 apply (frule less_mod_eq_imp_add_divisor_le[where m=m], simp)
 apply (drule add_le_imp_le_right)
 apply simp
apply simp
done

lemma iFROM_pred_insert_conv: "insert (n - Suc 0) [n…] = [n - Suc 0…]"
by (fastforce simp: iFROM_iff)

lemma iIN_pred_insert_conv: "
  0 < n  insert (n - Suc 0) [n…,d] = [n - Suc 0…,Suc d]"
by (fastforce simp: iIN_iff)

lemma iMOD_pred_insert_conv: "
  m  r  insert (r - m) [r, mod m] = [r - m, mod m]"
apply (case_tac "m = 0")
 apply (simp add: iMOD_iff insert_absorb)
apply simp
apply (rule set_eqI)
apply (simp add: iMOD_iff mod_diff_self2)
apply (rule iffI)
 apply (erule disjE)
  apply (simp add: mod_diff_self2)
 apply (simp add: le_imp_diff_le)
apply (erule conjE)
apply (drule order_le_less[THEN iffD1, of "r-m"], erule disjE)
 prefer 2
 apply simp
apply (frule order_less_le_trans[of _ m r], assumption)
apply (drule less_mod_eq_imp_add_divisor_le[of "r-m" _ m])
 apply (simp add: mod_diff_self2)
apply simp
done

lemma iMODb_pred_insert_conv: "
  m  r  insert (r - m) [r, mod m, c] = [r - m, mod m, Suc c]"
apply (rule set_eqI)
apply (frule iMOD_pred_insert_conv)
apply (drule_tac f="λs. x  s" in arg_cong)
apply (force simp: iMOD_iff iMODb_iff)
done

lemma iFROM_Suc_pred_insert_conv: "insert n [Suc n…] = [n…]"
by (insert iFROM_pred_insert_conv[of "Suc n"], simp)
lemma iIN_Suc_pred_insert_conv: "insert n [Suc n…,d] = [n…,Suc d]"
by (insert iIN_pred_insert_conv[of "Suc n"], simp)
lemma iMOD_Suc_pred_insert_conv: "insert r [r + m, mod m] = [r, mod m]"
by (insert iMOD_pred_insert_conv[of m "r + m"], simp)
lemma iMODb_Suc_pred_insert_conv: "insert r [r + m, mod m, c] = [r, mod m, Suc c]"
by (insert iMODb_pred_insert_conv[of m "r + m"], simp)

lemmas iT_Suc_insert =
  iIN_Suc_insert_conv
  iTILL_Suc_insert_conv
  iMODb_Suc_insert_conv
lemmas iT_pred_insert =
  iFROM_pred_insert_conv
  iIN_pred_insert_conv
  iMOD_pred_insert_conv
  iMODb_pred_insert_conv
lemmas iT_Suc_pred_insert =
  iFROM_Suc_pred_insert_conv
  iIN_Suc_pred_insert_conv
  iMOD_Suc_pred_insert_conv
  iMODb_Suc_pred_insert_conv

lemma iMOD_mem_diff: " a  [r, mod m]; b  [r, mod m]   (a - b) mod m = 0"
by (simp add: iMOD_iff mod_eq_imp_diff_mod_0)
lemma iMODb_mem_diff: " a  [r, mod m, c]; b  [r, mod m, c]   (a - b) mod m = 0"
by (simp add: iMODb_iff mod_eq_imp_diff_mod_0)



subsubsection ‹Interval conversions›

lemma iIN_0_iTILL_conv:"[0…,n] = […n]"
by (simp add: iTILL_def iIN_def atMost_atLeastAtMost_0_conv)
lemma iIN_iTILL_iTILL_conv: "0 < n  [n…,d] = […n+d] - […n - Suc 0]"
by (fastforce simp: iTILL_iff iIN_iff)
lemma iIN_iFROM_iTILL_conv: "[n…,d] = [n…]  […n+d]"
by (simp add: iT_defs atLeastAtMost_def)
lemma iMODb_iMOD_iTILL_conv: "[r, mod m, c] = [r, mod m]  […r+m*c]"
by (force simp: iT_defs set_interval_defs)
lemma iMODb_iMOD_iIN_conv: "[r, mod m, c] = [r, mod m]  [r…,m*c]"
by (force simp: iT_defs set_interval_defs)

lemma iFROM_iTILL_iIN_conv: "n  n'  [n…]  […n'] = [n…,n'-n]"
by (simp add: iT_defs atLeastAtMost_def)
lemma iMOD_iTILL_iMODb_conv: "
  r  n  [r, mod m]  […n] = [r, mod m, (n - r) div m]"
apply (rule set_eqI)
apply (simp add: iT_iff minus_mod_eq_mult_div [symmetric])
apply (rule iffI)
 apply clarify
 apply (frule_tac x=x and y=n and m=m in le_imp_sub_mod_le)
 apply (simp add: mod_diff_right_eq)
apply fastforce
done

lemma iMOD_iIN_iMODb_conv: "
  [r, mod m]  [r…,d] = [r, mod m, d div m]"
apply (case_tac "r = 0")
 apply (simp add: iIN_0_iTILL_conv iMOD_iTILL_iMODb_conv)
apply (simp add: iIN_iTILL_iTILL_conv Diff_Int_distrib iMOD_iTILL_iMODb_conv diff_add_inverse)
apply (rule subst[of "{}" _ "λt. x.(x - t) = x", THEN spec])
 prefer 2
 apply simp
apply (rule sym)
apply (fastforce simp: disjoint_iff_not_equal iMOD_iff iTILL_iff)
done

lemma iFROM_0: "[0…] = UNIV"
by (simp add: iFROM_def)

lemma iTILL_0: "[…0] = {0}"
by (simp add: iTILL_def)

lemma iIN_0: "[n…,0] = {n}"
by (simp add: iIN_def)

lemma iMOD_0: "[r, mod 0] = [r…,0]"
by (fastforce simp: iIN_0 iMOD_def)

lemma iMODb_mod_0: "[r, mod 0, c] = [r…,0]"
by (fastforce simp: iMODb_def iIN_0)

lemma iMODb_0: "[r, mod m, 0] = [r…,0]"
by (fastforce simp: iMODb_def iIN_0 set_eq_iff)

lemmas iT_0 =
  iFROM_0
  iTILL_0
  iIN_0
  iMOD_0
  iMODb_mod_0
  iMODb_0

lemma iMOD_1: "[r, mod Suc 0] = [r…]"
by (fastforce simp: iFROM_iff)

lemma iMODb_mod_1: "[r, mod Suc 0, c] = [r…,c]"
by (fastforce simp: iT_iff)


subsubsection ‹Finiteness and emptiness of intervals›

lemma 
  iFROM_not_empty: "[n…]  {}" and
  iTILL_not_empty: "[…n]  {}" and
  iIN_not_empty: "[n…,d]  {}" and
  iMOD_not_empty: "[r, mod m]  {}" and
  iMODb_not_empty: "[r, mod m, c]  {}"
by (fastforce simp: iT_iff)+

lemmas iT_not_empty = 
  iFROM_not_empty
  iTILL_not_empty
  iIN_not_empty
  iMOD_not_empty
  iMODb_not_empty

lemma 
  iTILL_finite: "finite […n]" and
  iIN_finite: "finite [n…,d]" and
  iMODb_finite: "finite [r, mod m, c]" and
  iMOD_0_finite: "finite [r, mod 0]"
by (simp add: iT_defs)+

lemma iFROM_infinite: "infinite [n…]"
by (simp add: iT_defs infinite_atLeast)

lemma iMOD_infinite: "0 < m  infinite [r, mod m]"
apply (rule infinite_nat_iff_asc_chain[THEN iffD2])
 apply (rule iT_not_empty)
apply (rule ballI, rename_tac n)
apply (rule_tac x="n+m" in bexI, simp)
apply (simp add: iMOD_iff)
done

lemmas iT_finite =
  iTILL_finite
  iIN_finite
  iMODb_finite iMOD_0_finite

lemmas iT_infinite =
  iFROM_infinite
  iMOD_infinite


subsubsection Min› and Max› element of an interval›

lemma 
  iTILL_Min: "iMin […n] = 0" and
  iFROM_Min: "iMin [n…] = n" and
  iIN_Min:   "iMin [n…,d] = n" and
  iMOD_Min:  "iMin [r, mod m] = r" and
  iMODb_Min: "iMin [r, mod m, c] = r"
by (rule iMin_equality, (simp add: iT_iff)+)+

lemmas iT_Min = 
  iIN_Min
  iTILL_Min
  iFROM_Min
  iMOD_Min
  iMODb_Min

lemma 
  iTILL_Max: "Max […n] = n" and
  iIN_Max: "Max [n…,d] = n+d" and
  iMODb_Max: "Max [r, mod m, c] = r + m * c" and
  iMOD_0_Max: "Max [r, mod 0] = r"
by (rule Max_equality, (simp add: iT_iff iT_finite)+)+

lemmas iT_Max =
  iTILL_Max
  iIN_Max
  iMODb_Max
  iMOD_0_Max

lemma
  iTILL_iMax: "iMax […n] = enat n" and
  iIN_iMax: "iMax [n…,d] = enat (n+d)" and
  iMODb_iMax: "iMax [r, mod m, c] = enat (r + m * c)" and
  iMOD_0_iMax: "iMax [r, mod 0] = enat r" and
  iFROM_iMax: "iMax [n…] = " and
  iMOD_iMax: "0 < m  iMax [r, mod m] = "
by (simp add: iMax_def iT_finite iT_infinite iT_Max)+

lemmas iT_iMax =
  iTILL_iMax
  iIN_iMax
  iMODb_iMax
  iMOD_0_iMax
  iFROM_iMax
  iMOD_iMax


subsection ‹Adding and subtracting constants to interval elements›

lemma 
  iFROM_plus: "x  [n…]  x + k  [n…]" and
  iFROM_Suc: "x  [n…]  Suc x  [n…]" and
  iFROM_minus: " x  [n…]; k  x - n   x - k  [n…]" and
  iFROM_pred: "n < x   x - Suc 0  [n…]"
by (simp add: iFROM_iff)+

lemma 
  iTILL_plus: " x  […n]; k  n - x   x + k  […n]" and
  iTILL_Suc: "x < n  Suc x  […n]" and
  iTILL_minus: "x  […n]  x - k  […n]" and
  iTILL_pred: "x  […n]  x - Suc 0  […n]"
by (simp add: iTILL_iff)+

lemma iIN_plus: " x  [n…,d]; k  n + d - x   x + k  [n…,d]"
by (fastforce simp: iIN_iff)

lemma iIN_Suc: " x  [n…,d]; x < n + d   Suc x  [n…,d]"
by (simp add: iIN_iff)

lemma iIN_minus: " x  [n…,d]; k  x - n   x - k  [n…,d]"
by (fastforce simp: iIN_iff)

lemma iIN_pred: " x  [n…,d]; n < x   x - Suc 0  [n…,d]"
by (fastforce simp: iIN_iff)

lemma iMOD_plus_divisor_mult: "x  [r, mod m]  x + k * m  [r, mod m]"
by (simp add: iMOD_def)

corollary iMOD_plus_divisor: "x  [r, mod m]  x + m  [r, mod m]"
by (simp add: iMOD_def)

lemma iMOD_minus_divisor_mult: "
   x  [r, mod m]; k * m  x - r   x - k * m  [r, mod m]"
by (fastforce simp: iMOD_def mod_diff_mult_self1)

corollary iMOD_minus_divisor_mult2: "
   x  [r, mod m]; k  (x - r) div m   x - k * m  [r, mod m]"
apply (rule iMOD_minus_divisor_mult, assumption)
apply (clarsimp simp: iMOD_iff)
apply (drule mult_le_mono1[of _ _ m])
apply (simp add: mod_0_div_mult_cancel[THEN iffD1, OF mod_eq_imp_diff_mod_0])
done

corollary iMOD_minus_divisor: "
   x  [r, mod m]; m + r  x   x - m  [r, mod m]"
apply (frule iMOD_geD)
apply (insert iMOD_minus_divisor_mult[of x r m 1])
apply simp
done

lemma iMOD_plus: "
  x  [r, mod m]  (x + k  [r, mod m]) = (k mod m = 0)"
apply safe
 apply (drule iMOD_modD)+
 apply (rule mod_add_eq_imp_mod_0[of x, THEN iffD1])
   apply simp
  apply (erule dvdE)
apply (simp add: mult.commute iMOD_plus_divisor_mult)
done
corollary iMOD_Suc: "
  x  [r, mod m]  (Suc x  [r, mod m]) = (m = Suc 0)"
apply (simp add: iMOD_iff, safe)
apply (simp add: mod_Suc, split if_split_asm)
apply simp+
done

lemma iMOD_minus: "
   x  [r, mod m]; k  x - r   (x - k  [r, mod m]) = (k mod m = 0)"
apply safe
 apply (clarsimp simp: iMOD_iff)
 apply (rule mod_add_eq_imp_mod_0[of "x - k" k, THEN iffD1])
   apply simp
  apply (erule dvdE)
apply (simp add: mult.commute iMOD_minus_divisor_mult)
done

corollary iMOD_pred: "
   x  [r, mod m]; r < x   (x - Suc 0  [r, mod m]) = (m = Suc 0)"
apply safe
 apply (simp add: iMOD_Suc[of "x - Suc 0" r, THEN iffD1])
apply (simp add: iMOD_iff)
done

lemma iMODb_plus_divisor_mult: "
   x  [r, mod m, c]; k * m  r + m * c - x   x + k * m  [r, mod m, c]"
by (fastforce simp: iMODb_def)

lemma iMODb_plus_divisor_mult2: "
   x  [r, mod m, c]; k  c - (x - r) div m   
  x + k * m  [r, mod m, c]"
apply (rule iMODb_plus_divisor_mult, assumption)
apply (clarsimp simp: iMODb_iff)
apply (drule mult_le_mono1[of _ _ m])
apply (simp add: diff_mult_distrib
  mod_0_div_mult_cancel[THEN iffD1, OF mod_eq_imp_diff_mod_0]
  add.commute[of r] mult.commute[of c])
done
lemma iMODb_plus_divisor: "
   x  [r, mod m, c]; x < r + m * c   x + m  [r, mod m, c]"
by (simp add: iMODb_iff less_mod_eq_imp_add_divisor_le)

lemma iMODb_minus_divisor_mult: "
   x  [r, mod m, c]; r + k * m  x    x - k * m  [r, mod m, c]"
by (fastforce simp: iMODb_def mod_diff_mult_self1)

lemma iMODb_plus: "
   x  [r, mod m, c]; k  r + m * c - x   
  (x + k  [r, mod m, c]) = (k mod m = 0)"
apply safe
 apply (rule mod_add_eq_imp_mod_0[of x, THEN iffD1])
 apply (simp add: iT_iff)
apply fastforce
done

corollary iMODb_Suc: "
   x  [r, mod m, c]; x < r + m * c   
  (Suc x  [r, mod m, c]) = (m = Suc 0)"
apply (rule iffI)
 apply (simp add: iMODb_iMOD_iTILL_conv iMOD_Suc)
apply (simp add: iMODb_iMOD_iTILL_conv iMOD_1 iFROM_Suc iTILL_Suc)
done

lemma iMODb_minus: "
   x  [r, mod m, c]; k  x - r   
  (x - k  [r, mod m, c]) = (k mod m = 0)"
apply (rule iffI)
 apply (simp add: iMODb_iMOD_iTILL_conv iMOD_minus)
apply (simp add: iMODb_iMOD_iTILL_conv iMOD_minus iTILL_minus)
done

corollary iMODb_pred: "
   x  [r, mod m, c]; r < x   
  (x - Suc 0  [r, mod m, c]) = (m = Suc 0)"
apply (rule iffI)
 apply (subgoal_tac "x  [r, mod m]  x - Suc 0  [r, mod m]")
  prefer 2
  apply (simp add: iT_iff)
 apply (clarsimp simp: iMOD_pred)
apply (fastforce simp add: iMODb_iff)
done

lemmas iFROM_plus_minus =
  iFROM_plus
  iFROM_Suc
  iFROM_minus
  iFROM_pred

lemmas iTILL_plus_minus =
  iTILL_plus
  iTILL_Suc
  iTILL_minus
  iTILL_pred

lemmas iIN_plus_minus =
  iIN_plus
  iIN_Suc
  iTILL_minus
  iIN_pred

lemmas iMOD_plus_minus_divisor =
  iMOD_plus_divisor_mult
  iMOD_plus_divisor
  iMOD_minus_divisor_mult
  iMOD_minus_divisor_mult2
  iMOD_minus_divisor

lemmas iMOD_plus_minus =
  iMOD_plus
  iMOD_Suc
  iMOD_minus
  iMOD_pred

lemmas iMODb_plus_minus_divisor =
  iMODb_plus_divisor_mult
  iMODb_plus_divisor_mult2
  iMODb_plus_divisor
  iMODb_minus_divisor_mult

lemmas iMODb_plus_minus =
  iMODb_plus
  iMODb_Suc
  iMODb_minus
  iMODb_pred

lemmas iT_plus_minus =
  iFROM_plus_minus
  iTILL_plus_minus
  iIN_plus_minus
  iMOD_plus_minus_divisor
  iMOD_plus_minus
  iMODb_plus_minus_divisor
  iMODb_plus_minus


(*
lemma "a ∈ [3…,2] ⟹ 3 ≤ a ∧ a ≤ 5"
by (simp add: iT_iff)
lemma "15 ∈ [5, mod 10]"
by (simp add: iT_iff)


lemma "n ∈ [15, mod 10] ⟹ n ∈ [5, mod 10]"
by (simp add: iT_iff)

lemma "[15, mod 10] ⊆ [5, mod 10]"
by (fastforce simp: iMOD_def)

lemma "n ≤ i ⟹ n ∈ […i]"
by (simp add: iT_iff)
lemma "∀n ∈ […i]. n ≤ i"
by (simp add: iT_iff)

lemma "∃n ∈ [2, mod 10].n ∉ [12, mod 10]"
apply (simp add: iT_defs)
apply (rule_tac x=2 in exI)
apply simp
done
*)


subsection ‹Relations between intervals›

subsubsection ‹Auxiliary lemmata›


lemma Suc_in_imp_not_subset_iMOD: "
   n  S; Suc n  S; m  Suc 0   ¬ S  [r, mod m]"
by (blast intro: iMOD_Suc[THEN iffD1])

corollary Suc_in_imp_neq_iMOD: "
   n  S; Suc n  S; m  Suc 0   S  [r, mod m]"
by (blast dest: Suc_in_imp_not_subset_iMOD)

lemma Suc_in_imp_not_subset_iMODb: "
   n  S; Suc n  S; m  Suc 0   ¬ S  [r, mod m, c]"
apply (rule ccontr, simp)
apply (frule subsetD[of _ _ n], assumption)
apply (drule subsetD[of _ _ "Suc n"], assumption)
apply (frule iMODb_Suc[THEN iffD1])
 apply (drule iMODb_leD[of "Suc n"])
 apply simp
apply blast+
done
corollary Suc_in_imp_neq_iMODb: "
   n  S; Suc n  S; m  Suc 0   S  [r, mod m, c]"
by (blast dest: Suc_in_imp_not_subset_iMODb)


subsubsection ‹Subset relation between intervals›

lemma 
  iIN_iFROM_subset_same: "[n…,d]  [n…]" and
  iIN_iTILL_subset_same: "[n…,d]  […n+d]" and
  iMOD_iFROM_subset_same: "[r, mod m]  [r…]" and
  iMODb_iTILL_subset_same: "[r, mod m, c]  […r+m*c]" and
  iMODb_iIN_subset_same: "[r, mod m, c]  [r…,m*c]" and
  iMODb_iMOD_subset_same: "[r, mod m, c]  [r, mod m]"
by (simp add: subset_iff iT_iff)+

lemmas iT_subset_same = 
  iIN_iFROM_subset_same
  iIN_iTILL_subset_same
  iMOD_iFROM_subset_same
  iMODb_iTILL_subset_same
  iMODb_iIN_subset_same
  iMODb_iTILL_subset_same
  iMODb_iMOD_subset_same

lemma iMODb_imp_iMOD: "x  [r, mod m, c]  x  [r, mod m]"
by (blast intro: iMODb_iMOD_subset_same)

lemma iMOD_imp_iMODb: "
   x  [r, mod m]; x  r + m * c   x  [r, mod m, c]"
by (simp add: iT_iff)

lemma iMOD_singleton_subset_conv: "([r, mod m]  {a}) = (r = a  m = 0)"
apply (rule iffI)
 apply (simp add: subset_singleton_conv iT_not_empty)
 apply (simp add: set_eq_iff iT_iff)
 apply (frule_tac x=r in spec, drule_tac x="r+m" in spec)
 apply simp
apply (simp add: iMOD_0 iIN_0)
done
lemma iMOD_singleton_eq_conv: "([r, mod m] = {a}) = (r = a  m = 0)"
apply (rule_tac t="[r, mod m] = {a}" and s="[r, mod m]  {a}" in subst)
 apply (simp add: subset_singleton_conv iMOD_not_empty)
apply (simp add: iMOD_singleton_subset_conv)
done

lemma iMODb_singleton_subset_conv: "
  ([r, mod m, c]  {a}) = (r = a  (m = 0  c = 0))"
apply (rule iffI)
 apply (simp add: subset_singleton_conv iT_not_empty)
 apply (simp add: set_eq_iff iT_iff)
 apply (frule_tac x=r in spec, drule_tac x="r+m" in spec)
 apply clarsimp
apply (fastforce simp: iMODb_0 iMODb_mod_0 iIN_0)
done
lemma iMODb_singleton_eq_conv: "
  ([r, mod m, c] = {a}) = (r = a  (m = 0  c = 0))"
apply (rule_tac t="[r, mod m, c] = {a}" and s="[r, mod m, c]  {a}" in subst)
 apply (simp add:  subset_singleton_conv iMODb_not_empty)
apply (simp add: iMODb_singleton_subset_conv)
done

lemma iMODb_subset_imp_divisor_mod_0: "
   0 < c'; [r', mod m', c']  [r, mod m, c]   m' mod m = 0"
apply (simp add: subset_iff iMODb_iff)
apply (drule gr0_imp_self_le_mult1[of _ m'])
apply (rule mod_add_eq_imp_mod_0[of r' m' m, THEN iffD1])
apply (frule_tac x=r' in spec, drule_tac x="r'+m'" in spec)
apply simp
done

lemma iMOD_subset_imp_divisor_mod_0: "
  [r', mod m']  [r, mod m]  m' mod m = 0"
apply (simp add: subset_iff iMOD_iff)
apply (rule mod_add_eq_imp_mod_0[of r' m' m, THEN iffD1])
apply simp
done

lemma iMOD_subset_imp_iMODb_subset: "
   [r', mod m']  [r, mod m]; r' + m' * c'  r + m * c   
  [r', mod m', c']  [r, mod m, c]"
by (simp add: subset_iff iT_iff)

lemma iMODb_subset_imp_iMOD_subset: "
   [r', mod m', c']  [r, mod m, c]; 0 < c'   
  [r', mod m']  [r, mod m]"
apply (frule subsetD[of _ _ r'])
 apply (simp add: iMODb_iff)
apply (rule subsetI)
apply (simp add: iMOD_iff iMODb_iff, clarify)
apply (drule mod_eq_mod_0_imp_mod_eq[where m=m and m'=m'])
 apply (simp add: iMODb_subset_imp_divisor_mod_0)
apply simp
done

lemma iMODb_0_iMOD_subset_conv: "
  ([r', mod m', 0]  [r, mod m]) = 
  (r' mod m = r mod m  r  r')"
by (simp add: iMODb_0 iIN_0 singleton_subset_conv iMOD_iff)

lemma iFROM_subset_conv: "([n'…]  [n…]) = (n  n')"
by (simp add: iFROM_def)

lemma iFROM_iMOD_subset_conv: "([n'…]  [r, mod m]) = (r  n'  m = Suc 0)"
apply (rule iffI)
 apply (rule conjI)
  apply (drule iMin_subset[OF iFROM_not_empty])
  apply (simp add: iT_Min)
 apply (rule ccontr)
 apply (cut_tac Suc_in_imp_not_subset_iMOD[of n' "[n'…]" m r])
 apply (simp add: iT_iff)+
apply (simp add: subset_iff iT_iff)
done

lemma iIN_subset_conv: "([n'…,d']  [n…,d]) = (n  n'  n'+d'  n+d)"
apply (rule iffI)
 apply (frule iMin_subset[OF iIN_not_empty])
 apply (drule Max_subset[OF iIN_not_empty _ iIN_finite])
 apply (simp add: iIN_Min iIN_Max)
apply (simp add: subset_iff iIN_iff)
done

lemma iIN_iFROM_subset_conv: "([n'…,d']  [n…]) = (n  n')"
by (fastforce simp: subset_iff iFROM_iff iIN_iff)

lemma iIN_iTILL_subset_conv: "([n'…,d']  […n]) = (n' + d'  n)"
by (fastforce simp: subset_iff iT_iff)

lemma iIN_iMOD_subset_conv: "
  0 < d'  ([n'…,d']  [r, mod m]) = (r  n'  m = Suc 0)"
apply (rule iffI)
 apply (frule iMin_subset[OF iIN_not_empty])
 apply (simp add: iT_Min)
 apply (subgoal_tac "n'  [n'…,d']")
  prefer 2
  apply (simp add: iIN_iff)
 apply (rule ccontr)
 apply (frule Suc_in_imp_not_subset_iMOD[where r=r and m=m])
 apply (simp add: iIN_Suc)+
apply (simp add: iMOD_1 iIN_iFROM_subset_conv)
done

lemma iIN_iMODb_subset_conv: "
  0 < d'  
  ([n'…,d']  [r, mod m, c]) = 
  (r  n'  m = Suc 0  n' + d'  r + m * c)"
apply (rule iffI)
 apply (frule subset_trans[OF _ iMODb_iMOD_subset_same])
 apply (simp add: iIN_iMOD_subset_conv iMODb_mod_1 iIN_subset_conv)
apply (clarsimp simp: iMODb_mod_1 iIN_subset_conv)
done


lemma iTILL_subset_conv: "([…n']  […n]) = (n'  n)"
by (simp add: iTILL_def)

lemma iTILL_iFROM_subset_conv: "([…n']  [n…]) = (n = 0)"
apply (rule iffI)
 apply (drule subsetD[of _ _ 0])
 apply (simp add: iT_iff)+
apply (simp add: iFROM_0)
done

lemma iTILL_iIN_subset_conv: "([…n']  [n…,d]) = (n = 0  n'  d)"
apply (rule iffI)
 apply (frule iMin_subset[OF iTILL_not_empty])
 apply (drule Max_subset[OF iTILL_not_empty _ iIN_finite])
 apply (simp add: iT_Min iT_Max)
apply (simp add: iIN_0_iTILL_conv iTILL_subset_conv)
done

lemma iTILL_iMOD_subset_conv: "
  0 < n'  ([…n']  [r, mod m]) = (r = 0  m = Suc 0)"
apply (drule iIN_iMOD_subset_conv[of n' 0 r m])
apply (simp add: iIN_0_iTILL_conv)
done

lemma iTILL_iMODb_subset_conv: "
  0 < n'  ([…n']  [r, mod m, c]) = (r = 0  m = Suc 0  n'  r + m * c)"
apply (drule iIN_iMODb_subset_conv[of n' 0 r m c])
apply (simp add: iIN_0_iTILL_conv)
done

lemma iMOD_iFROM_subset_conv: "([r', mod m'])  [n…] = (n  r')"
by (fastforce simp: subset_iff iT_iff)

lemma iMODb_iFROM_subset_conv: "([r', mod m', c']  [n…]) = (n  r')"
by (fastforce simp: subset_iff iT_iff)

lemma iMODb_iIN_subset_conv: "
  ([r', mod m', c']  [n…,d]) = (n  r'  r' + m' * c'  n + d)"
by (fastforce simp: subset_iff iT_iff)

lemma iMODb_iTILL_subset_conv: "
  ([r', mod m', c']  […n]) = (r' + m' * c'  n)"
by (fastforce simp: subset_iff iT_iff)

lemma iMOD_0_subset_conv: "([r', mod 0]  [r, mod m]) = (r' mod m = r mod m    r  r')"
by (fastforce simp: iMOD_0 iIN_0 singleton_subset_conv iMOD_iff)

lemma iMOD_subset_conv: "0 < m  
  ([r', mod m']  [r, mod m]) = 
  (r' mod m = r mod m    r  r'    m' mod m = 0)"
apply (rule iffI)
 apply (frule subsetD[of _ _ r'])
  apply (simp add: iMOD_iff)
 apply (drule iMOD_subset_imp_divisor_mod_0)
 apply (simp add: iMOD_iff)
apply (rule subsetI)
apply (simp add: iMOD_iff, elim conjE)
apply (drule mod_eq_mod_0_imp_mod_eq[where m'=m' and m=m])
apply simp+
done
 
lemma iMODb_subset_mod_0_conv: "
  ([r', mod m', c']  [r, mod 0, c ]) = (r'=r  (m'=0  c'=0))"
by (simp add: iMODb_mod_0 iIN_0 iMODb_singleton_subset_conv)

lemma iMODb_subset_0_conv: "
  ([r', mod m', c']  [r, mod m, 0 ]) = (r'=r  (m'=0  c'=0))"
by (simp add: iMODb_0 iIN_0 iMODb_singleton_subset_conv)

lemma iMODb_0_subset_conv: "
  ([r', mod m', 0]  [r, mod m, c ]) = (r'  [r, mod m, c])" 
by (simp add: iMODb_0 iIN_0)

lemma iMODb_mod_0_subset_conv: "
  ([r', mod 0, c']  [r, mod m, c ]) = (r'  [r, mod m, c])" 
by (simp add: iMODb_mod_0 iIN_0)

lemma iMODb_subset_conv': " 0 < c; 0 < c'   
  ([r', mod m', c']  [r, mod m, c]) = 
  (r' mod m = r mod m    r  r'    m' mod m = 0  
   r' + m' * c'  r + m * c)"
apply (rule iffI)
 apply (frule iMODb_subset_imp_iMOD_subset, assumption)
 apply (drule iMOD_subset_imp_divisor_mod_0)
 apply (frule subsetD[OF _ iMinI_ex2[OF iMODb_not_empty]])
 apply (drule Max_subset[OF iMODb_not_empty _ iMODb_finite])
 apply (simp add: iMODb_iff iMODb_Min iMODb_Max)
apply (elim conjE)
apply (case_tac "m = 0", simp add: iMODb_mod_0)
apply (simp add: iMOD_subset_imp_iMODb_subset iMOD_subset_conv)
done

lemma iMODb_subset_conv: " 0 < m'; 0 < c'   
  ([r', mod m', c']  [r, mod m, c]) = 
  (r' mod m = r mod m    r  r'    m' mod m = 0  
   r' + m' * c'  r + m * c)"
apply (case_tac "c = 0")
 apply (simp add: iMODb_0 iIN_0 iMODb_singleton_subset_conv linorder_not_le, intro impI)
 apply (case_tac "r' < r", simp)
 apply (simp add: linorder_not_less)
 apply (insert add_less_le_mono[of 0 "m' * c'" r r'])
 apply simp
apply (simp add: iMODb_subset_conv')
done

lemma iMODb_iMOD_subset_conv: "0 < c' 
  ([r', mod m', c']  [r, mod m]) = 
  (r' mod m = r mod m    r  r'    m' mod m = 0)"
apply (rule iffI)
 apply (frule subsetD[OF _ iMinI_ex2[OF iMODb_not_empty]])
 apply (simp add: iMODb_Min iMOD_iff, elim conjE)
 apply (simp add: iMODb_iMOD_iTILL_conv)
 apply (subgoal_tac "[ r', mod m', c' ]  [ r, mod m ]  […r' + m' * c']")
  prefer 2
  apply (simp add: iMODb_iMOD_iTILL_conv)
 apply (simp add: iMOD_iTILL_iMODb_conv iMODb_subset_imp_divisor_mod_0)
apply (rule subset_trans[OF iMODb_iMOD_subset_same])
apply (case_tac "m = 0", simp)
apply (simp add: iMOD_subset_conv)
done

lemmas iT_subset_conv =
  iFROM_subset_conv
  iFROM_iMOD_subset_conv
  iTILL_subset_conv
  iTILL_iFROM_subset_conv
  iTILL_iIN_subset_conv
  iTILL_iMOD_subset_conv
  iTILL_iMODb_subset_conv
  iIN_subset_conv
  iIN_iFROM_subset_conv
  iIN_iTILL_subset_conv
  iIN_iMOD_subset_conv
  iIN_iMODb_subset_conv
  iMOD_subset_conv
  iMOD_iFROM_subset_conv
  iMODb_subset_conv'
  iMODb_subset_conv
  iMODb_iFROM_subset_conv
  iMODb_iIN_subset_conv
  iMODb_iTILL_subset_conv
  iMODb_iMOD_subset_conv

lemma iFROM_subset: "n  n'  [n'…]  [n…]"
by (simp add: iFROM_subset_conv)

lemma not_iFROM_iIN_subset: "¬ [n'…]  [n…,d]"
apply (rule ccontr, simp)
apply (drule subsetD[of _ _ "max n' (Suc (n + d))"])
 apply (simp add: iFROM_iff)
apply (simp add: iIN_iff)
done

lemma not_iFROM_iTILL_subset: "¬ [n'…]  […n]"
by (simp add: iIN_0_iTILL_conv [symmetric] not_iFROM_iIN_subset)

lemma not_iFROM_iMOD_subset: "m  Suc 0  ¬ [n'…]  [r, mod m]"
apply (rule Suc_in_imp_not_subset_iMOD[of n'])
apply (simp add: iT_iff)+
done

lemma not_iFROM_iMODb_subset: "¬ [n'…]  [r, mod m, c]"
by (rule infinite_not_subset_finite[OF iFROM_infinite iMODb_finite])

lemma iIN_subset: " n  n'; n' + d'  n + d   [n'…,d']  [n…,d]"
by (simp add: iIN_subset_conv)

lemma iIN_iFROM_subset: "n  n'  [n'…,d']  [n…]"
by (simp add: subset_iff iT_iff)

lemma iIN_iTILL_subset: "n' + d'  n  [n'…,d']  […n]"
by (simp add: iIN_0_iTILL_conv[symmetric] iIN_subset)

lemma not_iIN_iMODb_subset: " 0 < d'; m  Suc 0   ¬ [n'…,d']  [r, mod m, c]"
apply (rule Suc_in_imp_not_subset_iMODb[of n'])
apply (simp add: iIN_iff)+
done

lemma not_iIN_iMOD_subset: " 0 < d'; m  Suc 0   ¬ [n'…,d']  [r, mod m]"
apply (rule ccontr, simp)
apply (case_tac "r  n' + d'")
 apply (drule Int_greatest[OF _ iIN_iTILL_subset[OF order_refl]])
 apply (simp add: iMOD_iTILL_iMODb_conv not_iIN_iMODb_subset)
apply (drule subsetD[of _ _ "n'+d'"])
apply (simp add: iT_iff)+
done

lemma iTILL_subset: "n'  n  […n']  […n]"
by (rule iTILL_subset_conv[THEN iffD2])

lemma iTILL_iFROM_subset: "([…n']  [0…])"
by (simp add: iFROM_0)

lemma iTILL_iIN_subset: "n'  d  ([…n']  [0…,d])"
by (simp add: iIN_0_iTILL_conv iTILL_subset)

lemma not_iTILL_iMOD_subset: "
   0 < n'; m  Suc 0   ¬ […n']  [r, mod m]"
by (simp add: iIN_0_iTILL_conv[symmetric] not_iIN_iMOD_subset)

lemma not_iTILL_iMODb_subset: "
   0 < n'; m  Suc 0   ¬ […n']  [r, mod m, c]"
by (simp add: iIN_0_iTILL_conv[symmetric] not_iIN_iMODb_subset)

lemma iMOD_iFROM_subset: "n  r'  [r', mod m']  [n…]"
by (rule iMOD_iFROM_subset_conv[THEN iffD2])

lemma not_iMOD_iIN_subset: "0 < m'  ¬ [r', mod m']  [n…,d]"
by (rule infinite_not_subset_finite[OF iMOD_infinite iIN_finite])

lemma not_iMOD_iTILL_subset: "0 < m'  ¬ [r', mod m']  […n]"
by (rule infinite_not_subset_finite[OF iMOD_infinite iTILL_finite])

lemma iMOD_subset: "
   r  r'; r' mod m = r mod m; m' mod m = 0   [r', mod m']  [r, mod m]"
apply (case_tac "m = 0", simp)
apply (simp add: iMOD_subset_conv)
done

lemma not_iMOD_iMODb_subset: "0 < m'  ¬ [r', mod m']  [r, mod m, c]"
by (rule infinite_not_subset_finite[OF iMOD_infinite iMODb_finite])

lemma iMODb_iFROM_subset: "n  r'  [r', mod m', c']  [n…]"
by (rule iMODb_iFROM_subset_conv[THEN iffD2])

lemma iMODb_iTILL_subset: "
  r' + m' * c'  n  [r', mod m', c']  […n]"
by (rule iMODb_iTILL_subset_conv[THEN iffD2])

lemma iMODb_iIN_subset: "
   n  r'; r' + m' * c'  n + d   [r', mod m', c']  [n…,d]"
by (simp add: iMODb_iIN_subset_conv)

lemma iMODb_iMOD_subset: "
   r  r'; r' mod m = r mod m; m' mod m = 0   [r', mod m', c']  [r, mod m]"
apply (case_tac "c' = 0")
 apply (simp add: iMODb_0 iIN_0 iMOD_iff)
apply (simp add: iMODb_iMOD_subset_conv)
done

lemma iMODb_subset: "
   r  r'; r' mod m = r mod m; m' mod m = 0; r' + m' * c'  r + m * c   
  [r', mod m', c']  [r, mod m, c]"
apply (case_tac "m' = 0")
 apply (simp add: iMODb_mod_0 iIN_0 iMODb_iff)
apply (case_tac "c' = 0")
 apply (simp add: iMODb_0 iIN_0 iMODb_iff)
apply (simp add: iMODb_subset_conv)
done

lemma iFROM_trans: " y  [x…]; z  [y…]   z  [x…]"
by (rule subsetD[OF iFROM_subset[OF iFROM_D]])

lemma iTILL_trans: " y  […x]; z  […y]   z  […x]"
by (rule subsetD[OF iTILL_subset[OF iTILL_D]])

lemma iIN_trans: "
   y  [x…,d]; z  [y…,d']; d'  x + d - y   z  [x…,d]"
by fastforce

lemma iMOD_trans: "
   y  [x, mod m]; z  [y, mod m]   z  [x, mod m]"
by (rule subsetD[OF iMOD_subset[OF iMOD_geD iMOD_modD mod_self]])

lemma iMODb_trans: "
   y  [x, mod m, c]; z  [y, mod m, c']; m * c'  x + m * c - y   
  z  [x, mod m, c]"
by fastforce

lemma iMODb_trans': "
   y  [x, mod m, c]; z  [y, mod m, c']; c'  x div m + c - y div m   
  z  [x, mod m, c]"
apply (rule iMODb_trans[where c'=c'], assumption+)
apply (frule iMODb_geD, frule div_le_mono[of x y m])
apply (simp add: add.commute[of _ c] add.commute[of _ "m*c"])
apply (drule mult_le_mono[OF le_refl, of _ _ m])
apply (simp add: add_mult_distrib2 diff_mult_distrib2 minus_mod_eq_mult_div [symmetric])
apply (simp add: iMODb_iff)
done


subsubsection ‹Equality of intervals›

lemma iFROM_eq_conv: "([n…] = [n'…]) = (n = n')"
apply (rule iffI)
 apply (drule set_eq_subset[THEN iffD1])
 apply (simp add: iFROM_subset_conv)
apply simp
done

lemma iIN_eq_conv: "([n…,d] = [n'…,d']) = (n = n'  d = d')"
apply (rule iffI)
 apply (drule set_eq_subset[THEN iffD1])
 apply (simp add: iIN_subset_conv)
apply simp
done

lemma iTILL_eq_conv: "([…n] = […n']) = (n = n')"
by (simp add: iIN_0_iTILL_conv[symmetric] iIN_eq_conv)

lemma iMOD_0_eq_conv: "([r, mod 0] = [r', mod m']) = (r = r'  m' = 0)"
apply (simp add: iMOD_0 iIN_0)
apply (simp add: iMOD_singleton_eq_conv eq_sym_conv[of "{r}"] eq_sym_conv[of "r"])
done

lemma iMOD_eq_conv: "0 < m  ([r, mod m] = [r', mod m']) = (r = r'  m = m')"
apply (case_tac "m' = 0")
 apply (simp add: eq_sym_conv[of "[r, mod m]"] iMOD_0_eq_conv)
apply (rule iffI)
 apply (fastforce simp add: set_eq_subset iMOD_subset_conv)
apply simp
done

lemma iMODb_mod_0_eq_conv: "
  ([r, mod 0, c] = [r', mod m', c']) = (r = r'  (m' = 0  c' = 0))"
apply (simp add: iMODb_mod_0 iIN_0)
apply (fastforce simp: iMODb_singleton_eq_conv eq_sym_conv[of "{r}"])
done

lemma iMODb_0_eq_conv: "
  ([r, mod m, 0] = [r', mod m', c']) = (r = r'  (m' = 0  c' = 0))"
apply (simp add: iMODb_0 iIN_0)
apply (fastforce simp: iMODb_singleton_eq_conv eq_sym_conv[of "{r}"])
done

lemma iMODb_eq_conv: " 0 < m; 0 < c   
  ([r, mod m, c] = [r', mod m', c']) = (r = r'  m = m'  c = c')"
apply (case_tac "c' = 0")
 apply (simp add: iMODb_0 iIN_0 iMODb_singleton_eq_conv)
apply (rule iffI)
 apply (fastforce simp: set_eq_subset iMODb_subset_conv')
apply simp
done

lemma iMOD_iFROM_eq_conv: "([n…] = [r, mod m]) = (n = r  m = Suc 0)"
by (fastforce simp: iMOD_1[symmetric] iMOD_eq_conv)

lemma iMODb_iIN_0_eq_conv: "
  ([n…,0] = [r, mod m, c]) = (n = r  (m = 0  c = 0))"
by (simp add: iIN_0 eq_commute[of "{n}"] eq_commute[of n] iMODb_singleton_eq_conv)

lemma iMODb_iIN_eq_conv: "
  0 < d  ([n…,d] = [r, mod m, c]) = (n = r  m = Suc 0  c = d)"
by (fastforce simp: iMODb_mod_1[symmetric] iMODb_eq_conv)


subsubsection ‹Inequality of intervals›

lemma iFROM_iIN_neq: "[n'…]  [n…,d]"
apply (rule ccontr)
apply (insert iFROM_infinite[of n'], insert iIN_finite[of n d])
apply simp
done

corollary iFROM_iTILL_neq: "[n'…]  […n]"
by (simp add: iIN_0_iTILL_conv[symmetric] iFROM_iIN_neq)

corollary iFROM_iMOD_neq: "m  Suc 0  [n…]  [r, mod m]"
apply (subgoal_tac "n  [n…]")
 prefer 2
 apply (simp add: iFROM_iff)
apply (simp add: Suc_in_imp_neq_iMOD iFROM_Suc)
done
corollary iFROM_iMODb_neq: "[n…]  [r, mod m, c]"
apply (rule ccontr)
apply (insert iMODb_finite[of r m c], insert iFROM_infinite[of n])
apply simp
done

corollary iIN_iMOD_neq: "0 < m  [n…,d]  [r, mod m]"
apply (rule ccontr)
apply (insert iMOD_infinite[of m r], insert iIN_finite[of n d])
apply simp
done

corollary iIN_iMODb_neq2: " m  Suc 0; 0 < d   [n…,d]  [r, mod m, c]"
apply (subgoal_tac "n  [n…,d]")
 prefer 2
 apply (simp add: iIN_iff)
apply (simp add: Suc_in_imp_neq_iMODb iIN_Suc)
done

lemma iIN_iMODb_neq: " 2  m; 0 < c   [n…,d]  [r, mod m, c]"
apply (simp add: nat_ge2_conv, elim conjE)
apply (case_tac "d=0")
 apply (rule not_sym)
 apply (simp add: iIN_0 iMODb_singleton_eq_conv)
apply (simp add: iIN_iMODb_neq2)
done

lemma iTILL_iIN_neq: "0 < n  […n']  [n…,d]"
by (fastforce simp: set_eq_iff iT_iff)

corollary iTILL_iMOD_neq: "0 < m  […n]  [r, mod m]"
by (simp add: iIN_0_iTILL_conv[symmetric] iIN_iMOD_neq)

corollary iTILL_iMODb_neq: "
   m  Suc 0; 0 < n   […n]  [r, mod m, c]"
by (simp add: iIN_0_iTILL_conv[symmetric] iIN_iMODb_neq2)

lemma iMOD_iMODb_neq: "0 < m  [r, mod m]  [r', mod m', c']"
apply (rule ccontr)
apply (insert iMODb_finite[of r' m' c'], insert iMOD_infinite[of m r])
apply simp
done

lemmas iT_neq = 
  iFROM_iTILL_neq iFROM_iIN_neq iFROM_iMOD_neq iFROM_iMODb_neq
  iTILL_iIN_neq iTILL_iMOD_neq iTILL_iMODb_neq
  iIN_iMOD_neq  iIN_iMODb_neq iIN_iMODb_neq2
  iMOD_iMODb_neq


subsection ‹Union and intersection of intervals›

lemma iFROM_union': "[n…]  [n'…] = [min n n'…]"
by (fastforce simp: iFROM_iff)

corollary iFROM_union: "n  n'  [n…]  [n'…] = [n…]"
by (simp add: iFROM_union' min_eqL)

lemma iFROM_inter': "[n…]  [n'…] = [max n n'…]"
by (fastforce simp: iFROM_iff)

corollary iFROM_inter: "n'  n  [n…]  [n'…] = [n…]"
by (simp add: iFROM_inter' max_eqL)

lemma iTILL_union': "[…n]  […n'] = […max n n']"
by (fastforce simp: iTILL_iff)

corollary iTILL_union: "n'  n  […n]  […n'] = […n]"
by (simp add: iTILL_union' max_eqL)

lemma iTILL_iFROM_union: "n  n'  […n']  [n…] = UNIV"
by (fastforce simp: iT_iff)

lemma iTILL_inter': "[…n]  […n'] = […min n n']"
by (fastforce simp: iT_iff)

corollary iTILL_inter: "n  n'  […n]  […n'] = […n]"
by (simp add: iTILL_inter' min_eqL)

text ‹
  Union and intersection for iIN 
  only when there intersection is not empty and 
  none of them is other's subset,
  for instance: 
  ..  n    ..   n+d
  ..      n'    ..   n'+d'
›
lemma iIN_union: "
   n  n'; n'  Suc (n + d); n + d  n' + d'   
  [n…,d]  [n'…,d'] = [n…,n' - n + d'] "
by (fastforce simp add: iIN_iff)

(* The case of the second interval starting directly after the first one *)
lemma iIN_append_union: "
  [n…,d]  [n + d…,d'] = [n…,d + d']"
by (simp add: iIN_union)

lemma iIN_append_union_Suc: "
  [n…,d]  [Suc (n + d)…,d'] = [n…,Suc (d + d')]"
by (simp add: iIN_union)

lemma iIN_append_union_pred: "
  0 < d  [n…,d - Suc 0]  [n + d…,d'] = [n…,d + d']"
by (simp add: iIN_union)

lemma iIN_iFROM_union: "
  n'  Suc (n + d)  [n…,d]  [n'…] = [min n n'…]"
by (fastforce simp: iIN_iff)

lemma iIN_iFROM_append_union: "
  [n…,d]  [n + d…] = [n…]"
by (simp add: iIN_iFROM_union min_eqL)

lemma iIN_iFROM_append_union_Suc: "
  [n…,d]  [Suc (n + d)…] = [n…]"
by (simp add: iIN_iFROM_union min_eqL)

lemma iIN_iFROM_append_union_pred: "
  0 < d  [n…,d - Suc 0]  [n + d…] = [n…]"
by (simp add: iIN_iFROM_union min_eqL)


lemma iIN_inter: "
   n  n'; n'  n + d; n + d  n' + d'  
  [n…,d]  [n'…,d'] = [n'…,n + d - n']"
by (fastforce simp: iIN_iff)

lemma iMOD_union: "
   r  r'; r mod m = r' mod m  
  [r, mod m]  [r', mod m] = [r, mod m]"
by (fastforce simp: iT_iff)
lemma iMOD_union': "
  r mod m = r' mod m 
  [r, mod m]  [r', mod m] = [min r r', mod m]"
apply (case_tac "r  r'")
apply (fastforce simp: iMOD_union min_eq)+
done

lemma iMOD_inter: "
   r  r'; r mod m = r' mod m  
  [r, mod m]  [r', mod m] = [r', mod m]"
by (fastforce simp: iT_iff)

lemma iMOD_inter': "
  r mod m = r' mod m  
  [r, mod m]  [r', mod m] = [max r r', mod m]"
apply (case_tac "r  r'")
apply (fastforce simp: iMOD_inter max_eq)+
done

lemma iMODb_union: "
   r  r'; r mod m = r' mod m; r'  r + m * c; r + m * c  r' + m * c'  
  [r, mod m, c]  [r', mod m, c'] = [r, mod m, r' div m - r div m + c']"
apply (rule set_eqI)
apply (simp add: iMODb_iff)
apply (drule sym[of "r mod m"], simp)
apply (fastforce simp: add_mult_distrib2 diff_mult_distrib2 minus_mod_eq_mult_div [symmetric])
done

lemma iMODb_append_union: "
  [r, mod m, c]  [ r + m * c, mod m, c'] = [r, mod m, c + c']"
apply (insert iMODb_union[of r "r + m * c" m c c'])
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0)
apply simp
done

lemma iMODb_iMOD_append_union': "
   r mod m = r' mod m; r'  r + m * Suc c    
  [r, mod m, c]  [ r', mod m ] = [min r r', mod m]"
apply (subgoal_tac "(min r r') mod m = r' mod m")
 prefer 2
 apply (simp add: min_def)
apply (rule set_eqI)
apply (simp add: iT_iff)
apply (drule sym[of "r mod m"], simp)
apply (rule iffI)
 apply fastforce
apply (clarsimp simp: linorder_not_le)
apply (case_tac "r  r'")
apply (simp add: min_eqL)
apply (rule add_le_imp_le_right[of _ m])
apply (rule less_mod_eq_imp_add_divisor_le)
apply simp+
done

lemma iMODb_iMOD_append_union: "
   r  r'; r mod m = r' mod m; r'  r + m * Suc c    
  [r, mod m, c]  [ r', mod m ] = [r, mod m]"
by (simp add: iMODb_iMOD_append_union' min_eqL)

lemma iMODb_append_union_Suc: "
  [r, mod m, c]  [ r + m * Suc c, mod m, c'] = [r, mod m, Suc (c + c')]"
apply (subst insert_absorb[of "r + m * c" "[r, mod m, c]  [ r + m * Suc c, mod m, c']", symmetric])
 apply (simp add: iT_iff)
apply (simp del: Un_insert_right add: Un_insert_right[symmetric] add.commute[of m] add.assoc[symmetric] iMODb_Suc_pred_insert_conv)
apply (simp add: iMODb_append_union)
done

lemma iMODb_append_union_pred: "
  0 < c  [r, mod m, c - Suc 0]  [ r + m * c, mod m, c'] = [r, mod m, c + c']"
by (insert iMODb_append_union_Suc[of r m "c - Suc 0" c'], simp)


lemma iMODb_inter: "
   r  r'; r mod m = r' mod m; r'  r + m * c; r + m * c  r' + m * c'  
  [r, mod m, c]  [r', mod m, c'] = [r', mod m, c - (r'-r) div m]"
apply (rule set_eqI)
apply (simp add: iMODb_iff)
apply (simp add: diff_mult_distrib2)
apply (simp add: mult.commute[of _ "(r' - r) div m"])
apply (simp add: mod_0_div_mult_cancel[THEN iffD1, OF mod_eq_imp_diff_mod_0])
apply (simp add: add.commute[of _ r])
apply fastforce
done


lemmas iT_union' = 
  iFROM_union'
  iTILL_union'
  iMOD_union'
  iMODb_iMOD_append_union'
lemmas iT_union =
  iFROM_union
  iTILL_union
  iTILL_iFROM_union
  iIN_union
  iIN_iFROM_union
  iMOD_union
  iMODb_union
lemmas iT_union_append =
  iIN_append_union
  iIN_append_union_Suc
  iIN_append_union_pred
  iIN_iFROM_append_union
  iIN_iFROM_append_union_Suc
  iIN_iFROM_append_union_pred
  iMODb_append_union
  iMODb_iMOD_append_union
  iMODb_append_union_Suc
  iMODb_append_union_pred

lemmas iT_inter' =
  iFROM_inter'
  iTILL_inter'
  iMOD_inter'
lemmas iT_inter =
  iFROM_inter
  iTILL_inter
  iIN_inter
  iMOD_inter
  iMODb_inter


lemma mod_partition_Union: "
  0 < m  (k. A  [k * m…,m - Suc 0]) = A"
apply simp
apply (rule subst[where s=UNIV and P="λx. A  x = A"])
apply (rule set_eqI)
 apply (simp add: iT_iff)
 apply (rule_tac x="x div m" in exI)
 apply (simp add: div_mult_cancel)
 apply (subst add.commute)
 apply (rule le_add_diff)
 apply (simp add: Suc_mod_le_divisor)
apply simp
done

lemma finite_mod_partition_Union: "
   0 < m; finite A  
  (kMax A div m. A  [k*m…,m - Suc 0]) = A"
apply (rule subst[OF mod_partition_Union[of m], where
  P="λx. (kMax A div m. A  [k*m…,m - Suc 0]) = x"])
 apply assumption
apply (rule set_eqI)
apply (simp add: iIN_iff)
apply (rule iffI, blast)
apply clarsimp
apply (rename_tac x x1)
apply (rule_tac x="x div m" in bexI)
apply (frule in_imp_not_empty[where A=A])
apply (frule_tac Max_ge, assumption)
apply (cut_tac n=x and k="x div m" and m=m in div_imp_le_less)
apply clarsimp+
apply (drule_tac m=x in less_imp_le_pred)
apply (simp add: add.commute[of m])
apply (simp add: div_le_mono)
done

lemma mod_partition_is_disjoint: "
   0 < (m::nat); k  k'   
  (A  [k * m…,m - Suc 0])   (A  [k' * m…,m - Suc 0]) = {}"
apply (clarsimp simp add: all_not_in_conv[symmetric] iT_iff)
apply (subgoal_tac "k.  k * m  x; x  k * m + m - Suc 0   x div m = k")
 apply blast
apply (rule le_less_imp_div, assumption)
apply simp
done


subsection ‹Cutting intervals›

(*
lemma "[10…,5] ↓< 12 = [10…,1]"
apply (simp add: iT_iff cut_less_def)
apply (simp add: iT_defs set_interval_defs Collect_conj_eq[symmetric])
apply fastforce
done
*)

lemma iTILL_cut_le: "[…n] ↓≤ t = (if t  n then […t] else […n])"
unfolding i_cut_defs iT_defs atMost_def
by force

corollary iTILL_cut_le1: "t  […n]  […n] ↓≤ t = […t]"
by (simp add: iTILL_cut_le iT_iff)

corollary iTILL_cut_le2: "t  […n]  […n] ↓≤ t = […n]"
by (simp add: iTILL_cut_le iT_iff)


lemma iFROM_cut_le: "
  [n…] ↓≤ t = 
  (if t < n then {} else [n…,t-n])"
by (simp add: set_eq_iff i_cut_mem_iff iT_iff)

corollary iFROM_cut_le1: "t  [n…]  [n…] ↓≤ t = [n…,t - n]"
by (simp add: iFROM_cut_le iT_iff) 

lemma iIN_cut_le: "
  [n…,d] ↓≤ t = (
  if t < n then {} else 
  if t  n+d then [n…,t-n]
  else [n…,d])"
by (force simp: set_eq_iff i_cut_mem_iff iT_iff)

corollary iIN_cut_le1: "
  t  [n…,d]  [n…,d] ↓≤ t = [n…,t - n]"
by (simp add: iIN_cut_le iT_iff)


lemma iMOD_cut_le: "
  [r, mod m] ↓≤ t = (
  if t < r then {} 
  else [r, mod m, (t - r) div m])"
apply (case_tac "m = 0")
 apply (simp add: iMOD_0 iMODb_0 iIN_0 i_cut_empty i_cut_singleton)
apply (case_tac "t < r")
 apply (simp add: cut_le_Min_empty iMOD_Min)
apply (clarsimp simp: linorder_not_less set_eq_iff i_cut_mem_iff iT_iff)
apply (rule conj_cong, simp)+
apply (clarsimp simp: minus_mod_eq_mult_div [symmetric])
apply (drule_tac x=r and y=x in le_imp_less_or_eq, erule disjE)
 prefer 2
 apply simp
apply (drule_tac x=r and y=x and m=m in less_mod_eq_imp_add_divisor_le, simp)
apply (rule iffI)
 apply (rule_tac x=x in subst[OF mod_eq_imp_diff_mod_eq[of _ m r t], rule_format], simp+)
 apply (subgoal_tac "r + (t - x) mod m  t")
  prefer 2
  apply (simp add: order_trans[OF add_le_mono2[OF mod_le_divisor]])
 apply simp
 apply (simp add: le_imp_sub_mod_le)
apply (subgoal_tac "r + (t - r) mod m  t")
 prefer 2
 apply (rule ccontr)
 apply simp
apply simp
done

lemma iMOD_cut_le1: "
  t  [r, mod m]  
  [r, mod m] ↓≤ t = [r, mod m, (t - r) div m]"
by (simp add: iMOD_cut_le iT_iff)

lemma iMODb_cut_le: "
  [r, mod m, c] ↓≤ t = (
    if t < r then {} 
    else if t < r + m * c then [r, mod m, (t - r) div m]
    else [r, mod m, c])"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iIN_0 cut_le_singleton)
apply (case_tac "t < r")
 apply (simp add: cut_le_Min_empty iT_Min)
apply (case_tac "r + m * c  t")
 apply (simp add: cut_le_Max_all iT_Max iT_finite)
apply (simp add: linorder_not_le linorder_not_less)
apply (rule_tac t=c and s="(r + m * c - r) div m" in subst, simp)
apply (subst iMOD_iTILL_iMODb_conv[symmetric], simp)
apply (simp add: cut_le_Int_right iTILL_cut_le)
apply (simp add: iMOD_iTILL_iMODb_conv)
done

lemma iMODb_cut_le1: "
  t  [r, mod m, c]  
  [r, mod m, c] ↓≤ t = [r, mod m, (t - r) div m]"
by (clarsimp simp: iMODb_cut_le iT_iff iMODb_mod_0)


lemma iTILL_cut_less: "
  […n] ↓< t = (
    if n < t then […n] else
    if t = 0 then {} 
    else […t - Suc 0])"
apply (case_tac "n < t")
 apply (simp add: cut_less_Max_all iT_Max iT_finite)
apply (case_tac "t = 0")
 apply (simp add: cut_less_0_empty)
apply (fastforce simp: nat_cut_less_le_conv iTILL_cut_le)
done

lemma iTILL_cut_less1: "
   t  […n]; 0 < t   […n] ↓< t = […t - Suc 0]"
by (simp add: iTILL_cut_less iT_iff)


lemma iFROM_cut_less: "
  [n…] ↓< t = (
    if t  n then {}
    else [n…,t - Suc n])"
apply (case_tac "t  n")
 apply (simp add: cut_less_Min_empty iT_Min)
apply (fastforce simp: nat_cut_less_le_conv iFROM_cut_le)
done

lemma iFROM_cut_less1: "
  n < t  [n…] ↓< t = [n…,t - Suc n]"
by (simp add: iFROM_cut_less)


lemma iIN_cut_less: "
  [n…,d] ↓< t = ( 
    if t  n then {} else
    if t  n + d then [n…, t - Suc n]
    else [n…,d])"
apply (case_tac "t  n")
 apply (simp add: cut_less_Min_empty iT_Min )
apply (case_tac "n + d < t")
 apply (simp add: cut_less_Max_all iT_Max iT_finite)
apply (fastforce simp: nat_cut_less_le_conv iIN_cut_le)
done


lemma iIN_cut_less1: "
   t  [n…,d]; n < t   [n…,d] ↓< t = [n…, t - Suc n]"
by (simp add: iIN_cut_less iT_iff)

lemma iMOD_cut_less: "
  [r, mod m] ↓< t = (
    if t  r then {} 
    else [r, mod m, (t - Suc r) div m])"
apply (case_tac "t = 0")
 apply (simp add: cut_less_0_empty)
apply (simp add: nat_cut_less_le_conv iMOD_cut_le)
apply fastforce
done

lemma iMOD_cut_less1: "
   t  [r, mod m]; r < t   
  [r, mod m] ↓< t = [r, mod m, (t - r) div m - Suc 0]"
apply (case_tac "m = 0")
 apply (simp add: iMOD_0 iMODb_mod_0 iIN_0)
apply (simp add: iMOD_cut_less)
apply (simp add: mod_0_imp_diff_Suc_div_conv mod_eq_imp_diff_mod_0 iT_iff)
done

lemma iMODb_cut_less: "
  [r, mod m, c] ↓< t = (
    if t  r then {} else
    if r + m * c < t then [r, mod m, c]
    else [r, mod m, (t - Suc r) div m])"
apply (case_tac "t = 0")
 apply (simp add: cut_less_0_empty)
apply (simp add: nat_cut_less_le_conv iMODb_cut_le)
apply fastforce
done

lemma iMODb_cut_less1: " t  [r, mod m, c]; r < t   
  [r, mod m, c] ↓< t = [r, mod m, (t - r) div m - Suc 0]"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iIN_0)
apply (simp add: iMODb_cut_less)
apply (simp add: mod_0_imp_diff_Suc_div_conv mod_eq_imp_diff_mod_0 iT_iff)
done


lemmas iT_cut_le =
  iTILL_cut_le
  iFROM_cut_le
  iIN_cut_le
  iMOD_cut_le
  iMODb_cut_le

lemmas iT_cut_le1 =
  iTILL_cut_le1
  iFROM_cut_le1
  iIN_cut_le1
  iMOD_cut_le1
  iMODb_cut_le1

lemmas iT_cut_less =
  iTILL_cut_less
  iFROM_cut_less
  iIN_cut_less
  iMOD_cut_less
  iMODb_cut_less

lemmas iT_cut_less1 =
  iTILL_cut_less1
  iFROM_cut_less1
  iIN_cut_less1
  iMOD_cut_less1
  iMODb_cut_less1

lemmas iT_cut_le_less =
  iTILL_cut_le
  iTILL_cut_less
  iFROM_cut_le
  iFROM_cut_less
  iIN_cut_le
  iIN_cut_less
  iMOD_cut_le
  iMOD_cut_less
  iMODb_cut_le
  iMODb_cut_less

lemmas iT_cut_le_less1 =
  iTILL_cut_le1
  iTILL_cut_less1
  iFROM_cut_le1
  iFROM_cut_less1
  iIN_cut_le1
  iIN_cut_less1
  iMOD_cut_le1
  iMOD_cut_less1
  iMODb_cut_le1
  iMODb_cut_less1

lemma iTILL_cut_ge: "
  […n] ↓≥ t = (if n < t then {} else [t…,n-t])"
by (force simp: i_cut_mem_iff iT_iff)

corollary iTILL_cut_ge1: "t  […n]  […n] ↓≥ t = [t…,n-t]"
by (simp add: iTILL_cut_ge iT_iff)

corollary iTILL_cut_ge2: "t  […n]  […n] ↓≥ t = {}"
by (simp add: iTILL_cut_ge iT_iff)

lemma iTILL_cut_greater: "
  […n] ↓> t = (if n  t then {} else [Suc t…,n - Suc t])"
by (force simp: i_cut_mem_iff iT_iff)

corollary iTILL_cut_greater1: "
  t  […n]  t < n  […n] ↓> t = [Suc t…,n - Suc t]"
by (simp add: iTILL_cut_greater iT_iff)

corollary iTILL_cut_greater2: "t  […n]  […n] ↓> t = {}"
by (simp add: iTILL_cut_greater iT_iff)


lemma iFROM_cut_ge: "
  [n…] ↓≥ t = (if n  t then [t…] else [n…])"
by (force simp: i_cut_mem_iff iT_iff)
corollary iFROM_cut_ge1: "t  [n…]  [n…] ↓≥ t = [t…]"
by (simp add: iFROM_cut_ge iT_iff) 

lemma iFROM_cut_greater: "
  [n…] ↓> t = (if n  t then [Suc t…] else [n…])"
by (force simp: i_cut_mem_iff iT_iff)
corollary iFROM_cut_greater1: "
  t  [n…]  [n…] ↓> t = [Suc t…]"
by (simp add: iFROM_cut_greater iT_iff) 

lemma iIN_cut_ge: "
  [n…,d] ↓≥ t = (
    if t < n then [n…,d] else 
    if t  n+d then [t…,n+d-t]
    else {})"
by (force simp: i_cut_mem_iff iT_iff)

corollary iIN_cut_ge1: "t  [n…,d]  
  [n…,d] ↓≥ t = [t…,n+d-t]"
by (simp add: iIN_cut_ge iT_iff) 

corollary iIN_cut_ge2: "t  [n…,d]  
  [n…,d] ↓≥ t = (if t < n then [n…,d] else {})"
by (simp add: iIN_cut_ge iT_iff)


lemma iIN_cut_greater: "
  [n…,d] ↓> t = (
    if t < n then [n…,d] else 
    if t < n+d then [Suc t…,n + d - Suc t]
    else {})"
by (force simp: i_cut_mem_iff iT_iff)

corollary iIN_cut_greater1: "
   t  [n…,d]; t < n + d 
  [n…,d] ↓> t = [Suc t…,n + d - Suc t]"
by (simp add: iIN_cut_greater iT_iff) 


(*
lemma "let m=5 in let r = 12 in let t = 16 in
  [r, mod m] ↓> t = (
  if t < r then [r, mod m] else
  if (m = 0 ∧ r ≤ t) then {}
  else [r + (t - r) div m * m + m, mod m])"
apply (simp add: Let_def)
oops
lemma "let m=5 in let r = 12 in let t = 16 in
  [r, mod m] ↓> t = (
  if t < r then [r, mod m] else
  if (m = 0 ∧ r ≤ t) then {}
  else [t + m - (t - r) mod m, mod m])"
apply (simp add: Let_def)
oops
*)

lemma mod_cut_greater_aux_t_less: "
   0 < (m::nat); r  t   
  t < t + m - (t - r) mod m"
by (simp add: less_add_diff add.commute)

lemma mod_cut_greater_aux_le_x: "
   (r::nat)  t; t < x; x mod m = r mod m  
  t + m - (t - r) mod m  x"
apply (insert diff_mod_le[of t r m])
apply (subst diff_add_assoc2, simp)
apply (rule less_mod_eq_imp_add_divisor_le, simp)
apply (simp add: sub_diff_mod_eq)
done

lemma iMOD_cut_greater: "
  [r, mod m] ↓> t = (
    if t < r then [r, mod m] else
    if m = 0 then {}
    else [t + m - (t - r) mod m, mod m])"
apply (case_tac "m = 0")
 apply (simp add: iMOD_0 iIN_0 i_cut_singleton)
apply (case_tac "t < r")
 apply (simp add: iT_Min cut_greater_Min_all)
apply (simp add: linorder_not_less)
apply (simp add: set_eq_iff i_cut_mem_iff iT_iff, clarify)
apply (subgoal_tac "(t - r) mod m  t")
 prefer 2
 apply (rule order_trans[OF mod_le_dividend], simp)
apply (simp add: diff_add_assoc2 del: add_diff_assoc2)
apply (simp add: sub_diff_mod_eq del: add_diff_assoc2)
apply (rule conj_cong, simp)
apply (rule iffI)
 apply clarify
 apply (rule less_mod_eq_imp_add_divisor_le)
  apply simp
 apply (simp add: sub_diff_mod_eq)
apply (subgoal_tac "t < x")
 prefer 2
 apply (rule_tac y="t - (t - r) mod m + m" in order_less_le_trans)
  apply (simp add: mod_cut_greater_aux_t_less)
 apply simp+
done

lemma iMOD_cut_greater1: "
  t  [r, mod m]  
  [r, mod m] ↓> t = (
    if m = 0 then {}
    else [t + m, mod m])"
by (simp add: iMOD_cut_greater iT_iff mod_eq_imp_diff_mod_0)

lemma iMODb_cut_greater_aux: "
   0 < m; t < r + m * c; r  t  
  (r + m * c - (t + m - (t - r) mod m)) div m =
  c - Suc ((t - r) div m)"
apply (subgoal_tac "r  t + m - (t - r) mod m")
 prefer 2
 apply (rule order_trans[of _ t], simp)
 apply (simp add: mod_cut_greater_aux_t_less less_imp_le)
apply (rule_tac t="(r + m * c - (t + m - (t - r) mod m))" and s="m * (c - Suc ((t - r) div m))" in subst)
 apply (simp add: diff_mult_distrib2 minus_mod_eq_mult_div [symmetric] del: diff_diff_left)
apply simp
done

lemma iMODb_cut_greater: "
  [r, mod m, c] ↓> t = (
    if t < r then [r, mod m, c] else
    if r + m * c  t then {}
    else [t + m - (t - r) mod m, mod m, c - Suc ((t-r) div m)])"
apply (case_tac "m = 0") 
 apply (simp add: iMODb_mod_0 iIN_0 i_cut_singleton)
apply (case_tac "r + m * c  t")
 apply (simp add: cut_greater_Max_empty iT_Max iT_finite)
apply (case_tac "t < r")
 apply (simp add: cut_greater_Min_all iT_Min)
apply (simp add: linorder_not_less linorder_not_le)
apply (rule_tac t="[ r, mod m, c ]" and s="[ r, mod m ]  […r + m * c]" in subst)
 apply (simp add: iMOD_iTILL_iMODb_conv)
apply (simp add: i_cut_Int_left iMOD_cut_greater)
apply (subst iMOD_iTILL_iMODb_conv)
 apply (rule mod_cut_greater_aux_le_x, simp+)
apply (simp add: iMODb_cut_greater_aux)
done

lemma iMODb_cut_greater1: "
  t  [r, mod m, c]  
    [r, mod m, c] ↓> t = (
    if r + m * c  t then {}
    else [t + m, mod m, c - Suc ((t-r) div m)])"
by (simp add: iMODb_cut_greater iT_iff mod_eq_imp_diff_mod_0)

(*
lemma "let m=5 in let r = 12 in let t = 17 in
  [r, mod m] ↓≥ t = (
  if t ≤ r then [r, mod m] else
  if m=0 then {}
  else [t + m - Suc ((t - Suc r) mod m), mod m])"
apply (simp add: Let_def)
oops
*)

lemma iMOD_cut_ge: "
  [r, mod m] ↓≥ t = (
    if t  r then [r, mod m] else
    if m = 0 then {} 
    else [t + m - Suc ((t - Suc r) mod m), mod m])"
apply (case_tac "t = 0")
 apply (simp add: cut_ge_0_all)
apply (force simp: nat_cut_greater_ge_conv[symmetric] iMOD_cut_greater)
done

lemma iMOD_cut_ge1: "
  t  [r, mod m]  
  [r, mod m] ↓≥ t = [t, mod m]"
by (fastforce simp: iMOD_cut_ge)

(*
lemma "let m=5 in let r = 12 in let t = 21 in let c=5 in
  [r, mod m, c] ↓≥ t = (
    if t ≤ r then [r, mod m, c] else
    if r + m * c < t then {} 
    else [t + m - Suc ((t - Suc r) mod m), mod m, c - (t + m - Suc r) div m])"
apply (simp add: Let_def)
oops
*)

lemma iMODb_cut_ge: "
  [r, mod m, c] ↓≥ t = (
    if t  r then [r, mod m, c] else
    if r + m * c < t then {} 
    else [t + m - Suc ((t - Suc r) mod m), mod m, c - (t + m - Suc r) div m])"
apply (case_tac "m = 0") 
 apply (simp add: iMODb_mod_0 iIN_0 i_cut_singleton)
apply (case_tac "r + m * c < t")
 apply (simp add: cut_ge_Max_empty iT_Max iT_finite)
apply (case_tac "t  r")
 apply (simp add: cut_ge_Min_all iT_Min)
apply (simp add: linorder_not_less linorder_not_le)
apply (case_tac "r mod m = t mod m")
 apply (simp add: diff_mod_pred)
 apply (simp add: mod_0_imp_diff_Suc_div_conv mod_eq_diff_mod_0_conv diff_add_assoc2 del: add_diff_assoc2)
 apply (subgoal_tac "0 < (t - r) div m")
  prefer 2
  apply (frule_tac x=r in less_mod_eq_imp_add_divisor_le)
   apply (simp add: mod_eq_diff_mod_0_conv)
  apply (drule add_le_imp_le_diff2)
  apply (drule_tac m=m and k=m in div_le_mono)
  apply simp
 apply (simp add: set_eq_iff i_cut_mem_iff iT_iff, intro allI)
 apply (simp add: mod_eq_diff_mod_0_conv[symmetric])
 apply (rule conj_cong, simp)
 apply (case_tac "t  x")
  prefer 2
  apply simp
 apply (simp add: diff_mult_distrib2 minus_mod_eq_mult_div [symmetric] mod_eq_diff_mod_0_conv add.commute[of r])
apply (subgoal_tac "Suc ((t - Suc r) mod m) = (t - r) mod m")
 prefer 2
 apply (clarsimp simp add: diff_mod_pred mod_eq_diff_mod_0_conv)
apply (rule_tac t="[ r, mod m, c ]" and s="[ r, mod m ]  […r + m * c]" in subst)
 apply (simp add: iMOD_iTILL_iMODb_conv)
apply (simp add: i_cut_Int_left iMOD_cut_ge)
apply (subst iMOD_iTILL_iMODb_conv)
 apply (drule_tac x=t in le_imp_less_or_eq, erule disjE)
 apply (rule mod_cut_greater_aux_le_x, simp+)
apply (rule arg_cong [where y="c - (t + m - Suc r) div m"])
apply (drule_tac x=t in le_imp_less_or_eq, erule disjE)
 prefer 2
 apply simp
apply (simp add: iMODb_cut_greater_aux)
apply (rule arg_cong[where f="(-) c"])
apply (simp add: diff_add_assoc2 del: add_diff_assoc2)
apply (rule_tac t="t - Suc r" and s="t - r - Suc 0" in subst, simp)
apply (subst div_diff1_eq[of _ "Suc 0"])
apply (case_tac "m = Suc 0", simp)
apply simp
done

lemma iMODb_cut_ge1: "
  t  [r, mod m, c] 
  [r, mod m, c] ↓≥ t = (
    if r + m * c < t then {} 
    else [t, mod m, c - (t - r) div m])"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iT_iff iIN_0 i_cut_singleton)
apply (clarsimp simp: iMODb_cut_ge iT_iff)
apply (simp add: mod_eq_imp_diff_mod_eq_divisor)
apply (rule_tac t="t + m - Suc r" and s="t - r + (m - Suc 0)" in subst, simp)
apply (subst div_add1_eq)
apply (simp add: mod_eq_imp_diff_mod_0)
done

lemma iMOD_0_cut_greater: "
  t  [r, mod 0]  [r, mod 0] ↓> t = {}"
by (simp add: iT_iff iMOD_0 iIN_0 i_cut_singleton)
lemma iMODb_0_cut_greater: "t  [r, mod 0, c] 
  [r, mod 0, c] ↓> t = {}"
by (simp add: iT_iff iMODb_mod_0 iIN_0 i_cut_singleton)

lemmas iT_cut_ge =
  iTILL_cut_ge
  iFROM_cut_ge
  iIN_cut_ge
  iMOD_cut_ge
  iMODb_cut_ge

lemmas iT_cut_ge1 =
  iTILL_cut_ge1
  iFROM_cut_ge1
  iIN_cut_ge1
  iMOD_cut_ge1
  iMODb_cut_ge1

lemmas iT_cut_greater =
  iTILL_cut_greater
  iFROM_cut_greater
  iIN_cut_greater
  iMOD_cut_greater
  iMODb_cut_greater

lemmas iT_cut_greater1 =
  iTILL_cut_greater1
  iFROM_cut_greater1
  iIN_cut_greater1
  iMOD_cut_greater1
  iMODb_cut_greater1

lemmas iT_cut_ge_greater =
  iTILL_cut_ge
  iTILL_cut_greater
  iFROM_cut_ge
  iFROM_cut_greater
  iIN_cut_ge
  iIN_cut_greater
  iMOD_cut_ge
  iMOD_cut_greater
  iMODb_cut_ge
  iMODb_cut_greater
lemmas iT_cut_ge_greater1 =
  iTILL_cut_ge1
  iTILL_cut_greater1
  iFROM_cut_ge1
  iFROM_cut_greater1
  iIN_cut_ge1
  iIN_cut_greater1
  iMOD_cut_ge1
  iMOD_cut_greater1
  iMODb_cut_ge1
  iMODb_cut_greater1


subsection ‹Cardinality of intervals›

lemma iFROM_card: "card [n…] = 0"
by (simp add: iFROM_infinite)

lemma iTILL_card: "card […n] = Suc n"
by (simp add: iTILL_def)

lemma iIN_card: "card [n…,d] = Suc d"
by (simp add: iIN_def)

lemma iMOD_0_card: "card [r, mod 0] = Suc 0"
by (simp add: iMOD_0 iIN_card)

lemma iMOD_card: "0 < m  card [r, mod m] = 0"
by (simp add: iMOD_infinite)

lemma iMOD_card_if: "card [r, mod m] = (if m = 0 then Suc 0 else 0)"
by (simp add: iMOD_0_card iMOD_card)

lemma iMODb_mod_0_card: "card [r, mod 0, c] = Suc 0"
by (simp add: iMODb_mod_0 iIN_card)

lemma iMODb_card: "0 < m  card [r, mod m, c] = Suc c"
apply (induct c)
 apply (simp add: iMODb_0 iIN_card)
apply (subst iMODb_Suc_insert_conv[symmetric])
apply (subst card_insert_disjoint)
apply (simp add: iT_finite iT_iff)+
done

lemma iMODb_card_if: "
  card [r, mod m, c] = (if m = 0 then Suc 0 else Suc c)"
by (simp add: iMODb_mod_0_card iMODb_card)

lemmas iT_card =
  iFROM_card
  iTILL_card
  iIN_card
  iMOD_card_if
  iMODb_card_if

text ‹Cardinality with icard›

lemma iFROM_icard: "icard [n…] = "
by (simp add: iFROM_infinite)

lemma iTILL_icard: "icard […n] = enat (Suc n)"
by (simp add: icard_finite iT_finite iT_card)

lemma iIN_icard: "icard [n…,d] = enat (Suc d)"
by (simp add: icard_finite iT_finite iT_card)

lemma iMOD_0_icard: "icard [r, mod 0] = eSuc 0"
by (simp add: icard_finite iT_finite iT_card eSuc_enat)

lemma iMOD_icard: "0 < m  icard [r, mod m] = "
by (simp add: iMOD_infinite)

lemma iMOD_icard_if: "icard [r, mod m] = (if m = 0 then eSuc 0 else )"
by (simp add: icard_finite iT_finite iT_infinite eSuc_enat iT_card)

lemma iMODb_mod_0_icard: "icard [r, mod 0, c] = eSuc 0"
by (simp add: icard_finite iT_finite eSuc_enat iT_card)

lemma iMODb_icard: "0 < m  icard [r, mod m, c] = enat (Suc c)"
by (simp add: icard_finite iT_finite iMODb_card)

lemma iMODb_icard_if: "icard [r, mod m, c] = enat (if m = 0 then Suc 0 else Suc c)"
by (simp add: icard_finite iT_finite iMODb_card_if)

lemmas iT_icard =
  iFROM_icard
  iTILL_icard
  iIN_icard
  iMOD_icard_if
  iMODb_icard_if


subsection ‹Functions inext› and iprev› with intervals›

(*
lemma "inext 5 […10] = 6"
apply (simp add: inext_def)
apply (simp add: iT_iff)
apply (simp add: iT_cut_greater)
apply (simp add: iT_not_empty)
apply (simp add: iT_Min)
done
lemma "inext 12 […10] = 12"
apply (simp add: inext_def)
apply (simp add: iT_iff)
done

lemma "inext 5 [4…,5] = 6"
apply (simp add: inext_def)
apply (simp add: iT_iff)
apply (simp add: iT_cut_greater)
apply (simp add: iT_not_empty)
apply (simp add: iT_Min)
done
lemma "inext 14 [2, mod 4] = 18"
apply (simp add: inext_def)
apply safe
apply (simp add: iMOD_cut_greater iT_iff 
  iT_Min)
apply (simp add: iT_iff)
apply (simp add: iMOD_cut_greater iT_iff 
  iT_not_empty)
done

lemma "iprev 5 […10] = 4"
apply (simp add: iprev_def)
apply (simp add: iT_iff)
apply (simp add: i_cut_defs)
apply safe
apply (simp add: iT_iff)
apply (rule le_antisym)
apply (rule iffD2[OF Max_le_iff])
apply fastforce+
done
*)

lemma 
  iFROM_inext: "t  [n…]  inext t [n…] = Suc t" and
  iTILL_inext: "t < n  inext t […n] = Suc t" and
  iIN_inext: " n  t; t < n + d   inext t [n…,d] = Suc t"
by (simp add: iT_defs inext_atLeast inext_atMost inext_atLeastAtMost)+

lemma 
  iFROM_iprev': "t  [n…]  iprev (Suc t) [n…] = t" and
  iFROM_iprev: "n < t   iprev t [n…] = t - Suc 0" and
  iTILL_iprev: "t  […n]  iprev t […n] = t - Suc 0" and
  iIN_iprev: " n < t; t  n + d   iprev t [n…,d] = t - Suc 0" and
  iIN_iprev': " n  t; t < n + d   iprev (Suc t) [n…,d] = t"
by (simp add: iT_defs iprev_atLeast iprev_atMost iprev_atLeastAtMost)+

lemma iMOD_inext: "t  [r, mod m]  inext t [r, mod m] = t + m"
by (clarsimp simp add: inext_def iMOD_cut_greater iT_iff iT_Min iT_not_empty mod_eq_imp_diff_mod_0)
lemma iMOD_iprev: " t  [r, mod m]; r < t   iprev t [r, mod m] = t - m"
apply (case_tac "m = 0", simp add: iMOD_iff)
apply (clarsimp simp add: iprev_def iMOD_cut_less iT_iff iT_Max iT_not_empty minus_mod_eq_mult_div [symmetric])
apply (simp del: add_Suc_right add: add_Suc_right[symmetric] mod_eq_imp_diff_mod_eq_divisor)
apply (simp add: less_mod_eq_imp_add_divisor_le)
done

lemma iMOD_iprev': "t  [r, mod m]  iprev (t + m) [r, mod m] = t"
apply (case_tac "m = 0")
 apply (simp add: iMOD_0 iIN_0 iprev_singleton)
apply (simp add: iMOD_iprev iT_iff)
done

lemma iMODb_inext: "
   t  [r, mod m, c]; t < r + m * c   
  inext t [r, mod m, c] = t + m"
by (clarsimp simp add: inext_def iMODb_cut_greater iT_iff iT_Min iT_not_empty mod_eq_imp_diff_mod_0)

lemma iMODb_iprev: "
   t  [r, mod m, c]; r < t   
  iprev t [r, mod m, c] = t - m"
apply (case_tac "m = 0", simp add: iMODb_iff)
apply (clarsimp simp add: iprev_def iMODb_cut_less iT_iff iT_Max iT_not_empty minus_mod_eq_mult_div [symmetric])
apply (simp del: add_Suc_right add: add_Suc_right[symmetric] mod_eq_imp_diff_mod_eq_divisor)
apply (simp add: less_mod_eq_imp_add_divisor_le)
done

lemma iMODb_iprev': "
   t  [r, mod m, c]; t < r + m * c   
  iprev (t + m) [r, mod m, c] = t"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iIN_0 iprev_singleton)
apply (simp add: iMODb_iprev iT_iff less_mod_eq_imp_add_divisor_le)
done

lemmas iT_inext =
  iFROM_inext
  iTILL_inext
  iIN_inext
  iMOD_inext
  iMODb_inext
lemmas iT_iprev =
  iFROM_iprev'
  iFROM_iprev
  iTILL_iprev
  iIN_iprev
  iIN_iprev'
  iMOD_iprev
  iMOD_iprev'
  iMODb_iprev
  iMODb_iprev'

lemma iFROM_inext_if: "
  inext t [n…] = (if t  [n…] then Suc t else t)"
by (simp add: iFROM_inext not_in_inext_fix)

lemma iTILL_inext_if: "
  inext t […n] = (if t < n then Suc t else t)"
by (simp add: iTILL_inext iT_finite iT_Max inext_ge_Max)

lemma iIN_inext_if: "
  inext t [n…,d] = (if n  t  t < n + d then Suc t else t)"
by (fastforce simp: iIN_inext iT_iff not_in_inext_fix iT_finite iT_Max inext_ge_Max)

lemma iMOD_inext_if: "
  inext t [r, mod m] = (if t  [r, mod m] then t + m else t)"
by (simp add: iMOD_inext not_in_inext_fix)

lemma iMODb_inext_if: "
  inext t [r, mod m, c] = 
  (if t  [r, mod m, c]  t < r + m * c then t + m else t)"
by (fastforce simp: iMODb_inext iT_iff not_in_inext_fix iT_finite iT_Max inext_ge_Max)

lemmas iT_inext_if =
  iFROM_inext_if
  iTILL_inext_if
  iIN_inext_if
  iMOD_inext_if
  iMODb_inext_if

lemma iFROM_iprev_if: "
  iprev t [n…] = (if n < t then t - Suc 0 else t)"
by (simp add: iFROM_iprev iT_Min iprev_le_iMin)
lemma iTILL_iprev_if: "
  iprev t […n] = (if t  […n] then t - Suc 0 else t)"
by (simp add: iTILL_iprev not_in_iprev_fix)
lemma iIN_iprev_if: "
  iprev t [n…,d] = (if n < t  t  n + d  then t - Suc 0 else t)"
by (fastforce simp: iIN_iprev iT_iff not_in_iprev_fix iT_Min iprev_le_iMin)
lemma iMOD_iprev_if: "
  iprev t [r, mod m] = 
  (if t  [r, mod m]  r < t then t - m else t)"
by (fastforce simp add: iMOD_iprev iT_iff not_in_iprev_fix iT_Min iprev_le_iMin)
lemma iMODb_iprev_if: "
  iprev t [r, mod m, c] = 
  (if t  [r, mod m, c]  r < t then t - m else t)"
by (fastforce simp add: iMODb_iprev iT_iff not_in_iprev_fix iT_Min iprev_le_iMin)

lemmas iT_iprev_if =
  iFROM_iprev_if
  iTILL_iprev_if
  iIN_iprev_if
  iMOD_iprev_if
  iMODb_iprev_if

text ‹
  The difference between an element and the next/previous element is constant
  if the element is different from Min/Max of the interval›

lemma iFROM_inext_diff_const: "
  t  [n…]  inext t [n…] - t = Suc 0"
by (simp add: iFROM_inext)

lemma iFROM_iprev_diff_const: "
  n < t  t - iprev t [n…] = Suc 0"
by (simp add: iFROM_iprev )

lemma iFROM_iprev_diff_const': "
  t  [n…]  Suc t - iprev (Suc t) [n…] = Suc 0"
by (simp add: iFROM_iprev')

lemma iTILL_inext_diff_const: "
  t < n  inext t […n] - t = Suc 0"
by (simp add: iTILL_inext)
lemma iTILL_iprev_diff_const: "
   t  […n]; 0 < t   t - iprev t […n] = Suc 0"
by (simp add: iTILL_iprev)

lemma iIN_inext_diff_const: "
   n  t; t < n + d   inext t [n…,d] - t = Suc 0"
by (simp add: iIN_inext)

lemma iIN_iprev_diff_const: "
   n < t; t  n + d   t - iprev t [n…,d] = Suc 0"
by (simp add: iIN_iprev)
lemma iIN_iprev_diff_const': "
   n  t; t < n + d   Suc t - iprev (Suc t) [n…,d] = Suc 0"
by (simp add: iIN_iprev)

lemma iMOD_inext_diff_const: "
  t  [r, mod m]  inext t [r, mod m] - t = m"
by (simp add: iMOD_inext)

lemma iMOD_iprev_diff_const': "
  t  [r, mod m]  (t + m) - iprev (t + m) [r, mod m] = m"
by (simp add: iMOD_iprev')

lemma iMOD_iprev_diff_const: "
   t  [r, mod m]; r < t   t - iprev t [r, mod m] = m"
apply (simp add: iMOD_iprev iT_iff)
apply (drule less_mod_eq_imp_add_divisor_le[where m=m], simp+)
done

lemma iMODb_inext_diff_const: "
   t  [r, mod m, c]; t < r + m * c   inext t [r, mod m, c] - t = m"
by (simp add: iMODb_inext)

lemma iMODb_iprev_diff_const': "
   t  [r, mod m, c]; t < r + m * c   (t + m) - iprev (t + m) [r, mod m, c] = m"
by (simp add: iMODb_iprev')

lemma iMODb_iprev_diff_const: "
   t  [r, mod m, c]; r < t   t - iprev t [r, mod m, c] = m"
apply (simp add: iMODb_iprev iT_iff)
apply (drule less_mod_eq_imp_add_divisor_le[where m=m], simp+)
done

lemmas iT_inext_diff_const =
  iFROM_inext_diff_const
  iTILL_inext_diff_const
  iIN_inext_diff_const
  iMOD_inext_diff_const
  iMODb_inext_diff_const
lemmas iT_iprev_diff_const =
  iFROM_iprev_diff_const
  iFROM_iprev_diff_const'
  iTILL_iprev_diff_const
  iIN_iprev_diff_const
  iIN_iprev_diff_const'
  iMOD_iprev_diff_const'
  iMOD_iprev_diff_const
  iMODb_iprev_diff_const'
  iMODb_iprev_diff_const


subsubsection ‹Mirroring of intervals›

lemma 
  iIN_mirror_elem: "mirror_elem x [n…,d] = n + n + d - x" and
  iTILL_mirror_elem: "mirror_elem x […n] = n - x" and
  iMODb_mirror_elem: "mirror_elem x [r, mod m, c] = r + r + m * c - x"
by (simp add: mirror_elem_def nat_mirror_def iT_Min iT_Max)+

lemma iMODb_imirror_bounds: "
  r' + m' * c'  l + r  
  imirror_bounds [r', mod m', c'] l r = [l + r - r' - m' * c', mod m', c']"
apply (clarsimp simp: set_eq_iff Bex_def imirror_bounds_iff iT_iff)
apply (frule diff_le_mono[of _ _ r'], simp)
apply (simp add: mod_diff_right_eq)
apply (rule iffI)
 apply (clarsimp, rename_tac x')
 apply (rule_tac a=x' in ssubst[OF mod_diff_right_eq, rule_format], simp+)
 apply (simp add: diff_le_mono2)
apply clarsimp
apply (rule_tac x="l+r-x" in exI)
apply (simp add: le_diff_swap)
apply (simp add: le_diff_conv2)
apply (subst mod_sub_eq_mod_swap, simp+)
apply (simp add: mod_diff_right_eq)
done

lemma iIN_imirror_bounds: "
  n + d  l + r  imirror_bounds [n…,d] l r = [l + r - n - d…,d]"
apply (insert iMODb_imirror_bounds[of n "Suc 0" d l r])
apply (simp add: iMODb_mod_1)
done

lemma iTILL_imirror_bounds: "
  n  l + r  imirror_bounds […n] l r = [l + r - n…,n]"
apply (insert iIN_imirror_bounds[of 0 n l r])
apply (simp add: iIN_0_iTILL_conv)
done

lemmas iT_imirror_bounds =
  iTILL_imirror_bounds
  iIN_imirror_bounds
  iMODb_imirror_bounds


lemma iMODb_imirror_ident: "imirror [r, mod m, c] = [r, mod m, c]"
by (simp add: imirror_eq_imirror_bounds iMODb_Min iMODb_Max iMODb_imirror_bounds)
lemma iIN_imirror_ident: "imirror [n…,d] = [n…,d]"
by (simp add: iMODb_mod_1[symmetric] iMODb_imirror_ident)
lemma iTILL_imirror_ident: "imirror […n] = […n]"
by (simp add: iIN_0_iTILL_conv[symmetric] iIN_imirror_ident)

lemmas iT_imirror_ident =
  iTILL_imirror_ident
  iIN_imirror_ident
  iMODb_imirror_ident


subsubsection ‹Functions @{term inext_nth} and @{term iprev_nth} on intervals›

lemma iFROM_inext_nth : "[n…]  a = n + a"
by (simp add: iT_defs inext_nth_atLeast)

lemma iIN_inext_nth : "a  d  [n…,d]  a = n + a"
by (simp add: iT_defs inext_nth_atLeastAtMost)

lemma iIN_iprev_nth: "a  d  [n…,d]  a = n + d - a"
by (simp add: iT_defs iprev_nth_atLeastAtMost)

lemma iIN_inext_nth_if : "
  [n…,d]  a = (if a  d then n + a else n + d)"
by (simp add: iIN_inext_nth inext_nth_card_Max iT_finite iT_not_empty iT_Max iT_card)

lemma iIN_iprev_nth_if: "
  [n…,d]  a = (if a  d then n + d - a else n)"
by (simp add: iIN_iprev_nth iprev_nth_card_iMin iT_finite iT_not_empty iT_Min iT_card)

lemma iTILL_inext_nth : "a  n  […n]  a = a"
by (simp add: iTILL_def inext_nth_atMost)

lemma iTILL_inext_nth_if : "
  […n]  a = (if a  n then a else n)"
by (insert iIN_inext_nth_if[of 0 n a], simp add: iIN_0_iTILL_conv)

lemma iTILL_iprev_nth: "a  n  […n]  a = n - a"
by (simp add: iTILL_def iprev_nth_atMost)

lemma iTILL_iprev_nth_if: "
  […n]  a= (if a  n then n - a else 0)"
by (insert iIN_iprev_nth_if[of 0 n a], simp add: iIN_0_iTILL_conv)


lemma iMOD_inext_nth: "[r, mod m]  a = r + m * a"
apply (induct a)
 apply (simp add: iT_Min)
apply (simp add: iMOD_inext_if iT_iff)
done

lemma iMODb_inext_nth: "a  c  [r, mod m, c]  a = r + m * a"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iIN_0 inext_nth_singleton)
apply (induct a)
 apply (simp add: iMODb_Min)
apply (simp add: iMODb_inext_if iT_iff)
done

lemma iMODb_inext_nth_if: "
  [r, mod m, c]  a = (if a  c then r + m * a else r + m * c)"
by (simp add: iMODb_inext_nth inext_nth_card_Max iT_finite iT_not_empty iT_Max iT_card)

lemma iMODb_iprev_nth: "
  a  c  [r, mod m, c]  a = r + m * (c - a)"
apply (case_tac "m = 0")
 apply (simp add: iMODb_mod_0 iIN_0 iprev_nth_singleton)
apply (induct a)
 apply (simp add: iMODb_Max)
apply (simp add: iMODb_iprev_if iT_iff)
apply (frule mult_left_mono[of _ _ m], simp)
apply (simp add: diff_mult_distrib2)
done

lemma iMODb_iprev_nth_if: "
  [r, mod m, c]  a = (if a  c then r + m * (c - a) else r)"
by (simp add: iMODb_iprev_nth iprev_nth_card_iMin iT_finite iT_not_empty iT_Min iT_card)


lemma iIN_iFROM_inext_nth: "
  a  d  [n…,d]  a = [n…]  a"
by (simp add: iIN_inext_nth iFROM_inext_nth)

lemma iIN_iFROM_inext: "
  a < n + d  inext a [n…,d] = inext a [n…]"
by (simp add: iT_inext_if iT_iff)

lemma iMOD_iMODb_inext_nth: "
  a  c  [r, mod m, c]  a = [r, mod m]  a"
by (simp add: iMOD_inext_nth iMODb_inext_nth)

lemma iMOD_iMODb_inext: "
  a < r + m * c  inext a [r, mod m, c] = inext a [r, mod m]"
by (simp add: iT_inext_if iT_iff)


lemma iMOD_inext_nth_Suc_diff: "
  ([r, mod m]  (Suc n)) - ([r, mod m]  n) = m"
by (simp add: iMOD_inext_nth del: inext_nth.simps)

lemma iMOD_inext_nth_diff: "
  ([r, mod m]  a) - ([r, mod m]  b) = (a - b) * m"
by (simp add: iMOD_inext_nth diff_mult_distrib mult.commute[of m])

lemma iMODb_inext_nth_diff: " a  c; b  c  
  ([r, mod m, c]  a) - ([r, mod m, c]  b) = (a - b) * m"
by (simp add: iMODb_inext_nth diff_mult_distrib  mult.commute[of m])



subsection ‹Induction with intervals›

lemma iFROM_induct: "
   P n; k.  k  [n…]; P k   P (Suc k); a  [n…]   P a"
apply (rule inext_induct[of _ "[n…]"])
apply (simp add: iT_Min iT_inext_if)+
done

lemma iIN_induct: "
   P n; k.  k  [n…,d]; k  n + d; P k   P (Suc k); a  [n…,d]   P a"
apply (rule inext_induct[of _ "[n…,d]"])
apply (simp add: iT_Min iT_inext_if)+
done

lemma iTILL_induct: "
   P 0; k.  k  […n]; k  n; P k   P (Suc k); a  […n]   P a"
apply (rule inext_induct[of _ "[…n]"])
apply (simp add: iT_Min iT_inext_if)+
done

lemma iMOD_induct: "
   P r; k.  k  [r, mod m]; P k   P (k + m); a  [r, mod m]   P a"
apply (rule inext_induct[of _ "[r, mod m]"])
apply (simp add: iT_Min iT_inext_if)+
done

lemma iMODb_induct: "
   P r; k.  k  [r, mod m, c]; k  r + m * c; P k   P (k + m); a  [r, mod m, c]   P a"
apply (rule inext_induct[of _ "[r, mod m, c]"])
apply (simp add: iT_Min iT_inext_if)+
done

lemma iIN_rev_induct: "
   P (n + d); k.  k  [n…,d]; k  n; P k   P (k - Suc 0); a  [n…,d]   P a"
apply (rule iprev_induct[of _ "[n…,d]"])
apply (simp add: iT_Max iT_finite iT_iprev_if)+
done

lemma iTILL_rev_induct: "
   P n; k.  k  […n]; 0 < k; P k   P (k - Suc 0); a  […n]   P a"
apply (rule iprev_induct[of _ "[…n]"])
apply (fastforce simp: iT_Max iT_finite iT_iprev_if)+
done

lemma iMODb_rev_induct: "
   P (r + m * c); k.  k  [r, mod m, c]; k  r; P k   P (k - m); a  [r, mod m, c]   P a"
apply (rule iprev_induct[of _ "[r, mod m, c]"])
apply (simp add: iT_Max iT_finite iT_iprev_if)+
done

end