(* Title: HOL/Word/Word_Miscellaneous.thy
Author: Miscellaneous
*)
section \<open>Miscellaneous lemmas, of at least doubtful value\<close>
theory Word_Miscellaneous
imports Main "~~/src/HOL/Library/Bit" Misc_Numeric
begin
lemma power_minus_simp:
"0 < n \<Longrightarrow> a ^ n = a * a ^ (n - 1)"
by (auto dest: gr0_implies_Suc)
lemma funpow_minus_simp:
"0 < n \<Longrightarrow> f ^^ n = f \<circ> f ^^ (n - 1)"
by (auto dest: gr0_implies_Suc)
lemma power_numeral:
"a ^ numeral k = a * a ^ (pred_numeral k)"
by (simp add: numeral_eq_Suc)
lemma funpow_numeral [simp]:
"f ^^ numeral k = f \<circ> f ^^ (pred_numeral k)"
by (simp add: numeral_eq_Suc)
lemma replicate_numeral [simp]:
"replicate (numeral k) x = x # replicate (pred_numeral k) x"
by (simp add: numeral_eq_Suc)
lemma rco_alt: "(f o g) ^^ n o f = f o (g o f) ^^ n"
apply (rule ext)
apply (induct n)
apply (simp_all add: o_def)
done
lemma list_exhaust_size_gt0:
assumes y: "\<And>a list. y = a # list \<Longrightarrow> P"
shows "0 < length y \<Longrightarrow> P"
apply (cases y, simp)
apply (rule y)
apply fastforce
done
lemma list_exhaust_size_eq0:
assumes y: "y = [] \<Longrightarrow> P"
shows "length y = 0 \<Longrightarrow> P"
apply (cases y)
apply (rule y, simp)
apply simp
done
lemma size_Cons_lem_eq:
"y = xa # list ==> size y = Suc k ==> size list = k"
by auto
lemmas ls_splits = prod.split prod.split_asm if_split_asm
lemma not_B1_is_B0: "y \<noteq> (1::bit) \<Longrightarrow> y = (0::bit)"
by (cases y) auto
lemma B1_ass_B0:
assumes y: "y = (0::bit) \<Longrightarrow> y = (1::bit)"
shows "y = (1::bit)"
apply (rule classical)
apply (drule not_B1_is_B0)
apply (erule y)
done
\<comment> "simplifications for specific word lengths"
lemmas n2s_ths [THEN eq_reflection] = add_2_eq_Suc add_2_eq_Suc'
lemmas s2n_ths = n2s_ths [symmetric]
lemma and_len: "xs = ys ==> xs = ys & length xs = length ys"
by auto
lemma size_if: "size (if p then xs else ys) = (if p then size xs else size ys)"
by auto
lemma tl_if: "tl (if p then xs else ys) = (if p then tl xs else tl ys)"
by auto
lemma hd_if: "hd (if p then xs else ys) = (if p then hd xs else hd ys)"
by auto
lemma if_Not_x: "(if p then ~ x else x) = (p = (~ x))"
by auto
lemma if_x_Not: "(if p then x else ~ x) = (p = x)"
by auto
lemma if_same_and: "(If p x y & If p u v) = (if p then x & u else y & v)"
by auto
lemma if_same_eq: "(If p x y = (If p u v)) = (if p then x = (u) else y = (v))"
by auto
lemma if_same_eq_not:
"(If p x y = (~ If p u v)) = (if p then x = (~u) else y = (~v))"
by auto
(* note - if_Cons can cause blowup in the size, if p is complex,
so make a simproc *)
lemma if_Cons: "(if p then x # xs else y # ys) = If p x y # If p xs ys"
by auto
lemma if_single:
"(if xc then [xab] else [an]) = [if xc then xab else an]"
by auto
lemma if_bool_simps:
"If p True y = (p | y) & If p False y = (~p & y) &
If p y True = (p --> y) & If p y False = (p & y)"
by auto
lemmas if_simps = if_x_Not if_Not_x if_cancel if_True if_False if_bool_simps
lemmas seqr = eq_reflection [where x = "size w"] for w (* FIXME: delete *)
lemma the_elemI: "y = {x} ==> the_elem y = x"
by simp
lemma nonemptyE: "S ~= {} ==> (!!x. x : S ==> R) ==> R" by auto
lemma gt_or_eq_0: "0 < y \<or> 0 = (y::nat)" by arith
lemmas xtr1 = xtrans(1)
lemmas xtr2 = xtrans(2)
lemmas xtr3 = xtrans(3)
lemmas xtr4 = xtrans(4)
lemmas xtr5 = xtrans(5)
lemmas xtr6 = xtrans(6)
lemmas xtr7 = xtrans(7)
lemmas xtr8 = xtrans(8)
lemmas nat_simps = diff_add_inverse2 diff_add_inverse
lemmas nat_iffs = le_add1 le_add2
lemma sum_imp_diff: "j = k + i ==> j - i = (k :: nat)" by arith
lemmas pos_mod_sign2 = zless2 [THEN pos_mod_sign [where b = "2::int"]]
lemmas pos_mod_bound2 = zless2 [THEN pos_mod_bound [where b = "2::int"]]
lemma nmod2: "n mod (2::int) = 0 | n mod 2 = 1"
by arith
lemmas eme1p = emep1 [simplified add.commute]
lemma le_diff_eq': "(a \<le> c - b) = (b + a \<le> (c::int))" by arith
lemma less_diff_eq': "(a < c - b) = (b + a < (c::int))" by arith
lemma diff_less_eq': "(a - b < c) = (a < b + (c::int))" by arith
lemmas m1mod22k = mult_pos_pos [OF zless2 zless2p, THEN zmod_minus1]
lemma z1pdiv2:
"(2 * b + 1) div 2 = (b::int)" by arith
lemmas zdiv_le_dividend = xtr3 [OF div_by_1 [symmetric] zdiv_mono2,
simplified int_one_le_iff_zero_less, simplified]
lemma axxbyy:
"a + m + m = b + n + n ==> (a = 0 | a = 1) ==> (b = 0 | b = 1) ==>
a = b & m = (n :: int)" by arith
lemma axxmod2:
"(1 + x + x) mod 2 = (1 :: int) & (0 + x + x) mod 2 = (0 :: int)" by arith
lemma axxdiv2:
"(1 + x + x) div 2 = (x :: int) & (0 + x + x) div 2 = (x :: int)" by arith
lemmas iszero_minus = trans [THEN trans,
OF iszero_def neg_equal_0_iff_equal iszero_def [symmetric]]
lemmas zadd_diff_inverse = trans [OF diff_add_cancel [symmetric] add.commute]
lemmas add_diff_cancel2 = add.commute [THEN diff_eq_eq [THEN iffD2]]
lemmas rdmods [symmetric] = mod_minus_eq
mod_diff_left_eq mod_diff_right_eq mod_add_left_eq
mod_add_right_eq mod_mult_right_eq mod_mult_left_eq
lemma mod_plus_right:
"((a + x) mod m = (b + x) mod m) = (a mod m = b mod (m :: nat))"
apply (induct x)
apply (simp_all add: mod_Suc)
apply arith
done
lemma nat_minus_mod: "(n - n mod m) mod m = (0 :: nat)"
by (induct n) (simp_all add : mod_Suc)
lemmas nat_minus_mod_plus_right = trans [OF nat_minus_mod mod_0 [symmetric],
THEN mod_plus_right [THEN iffD2], simplified]
lemmas push_mods' = mod_add_eq
mod_mult_eq mod_diff_eq
mod_minus_eq
lemmas push_mods = push_mods' [THEN eq_reflection]
lemmas pull_mods = push_mods [symmetric] rdmods [THEN eq_reflection]
lemmas mod_simps =
mod_mult_self2_is_0 [THEN eq_reflection]
mod_mult_self1_is_0 [THEN eq_reflection]
mod_mod_trivial [THEN eq_reflection]
lemma nat_mod_eq:
"!!b. b < n ==> a mod n = b mod n ==> a mod n = (b :: nat)"
by (induct a) auto
lemmas nat_mod_eq' = refl [THEN [2] nat_mod_eq]
lemma nat_mod_lem:
"(0 :: nat) < n ==> b < n = (b mod n = b)"
apply safe
apply (erule nat_mod_eq')
apply (erule subst)
apply (erule mod_less_divisor)
done
lemma mod_nat_add:
"(x :: nat) < z ==> y < z ==>
(x + y) mod z = (if x + y < z then x + y else x + y - z)"
apply (rule nat_mod_eq)
apply auto
apply (rule trans)
apply (rule le_mod_geq)
apply simp
apply (rule nat_mod_eq')
apply arith
done
lemma mod_nat_sub:
"(x :: nat) < z ==> (x - y) mod z = x - y"
by (rule nat_mod_eq') arith
lemma int_mod_eq:
"(0 :: int) <= b ==> b < n ==> a mod n = b mod n ==> a mod n = b"
by (metis mod_pos_pos_trivial)
lemmas int_mod_eq' = mod_pos_pos_trivial (* FIXME delete *)
lemma int_mod_le: "(0::int) <= a ==> a mod n <= a"
by (fact Divides.semiring_numeral_div_class.mod_less_eq_dividend) (* FIXME: delete *)
lemma mod_add_if_z:
"(x :: int) < z ==> y < z ==> 0 <= y ==> 0 <= x ==> 0 <= z ==>
(x + y) mod z = (if x + y < z then x + y else x + y - z)"
by (auto intro: int_mod_eq)
lemma mod_sub_if_z:
"(x :: int) < z ==> y < z ==> 0 <= y ==> 0 <= x ==> 0 <= z ==>
(x - y) mod z = (if y <= x then x - y else x - y + z)"
by (auto intro: int_mod_eq)
lemmas zmde = zmod_zdiv_equality [THEN diff_eq_eq [THEN iffD2], symmetric]
lemmas mcl = mult_cancel_left [THEN iffD1, THEN make_pos_rule]
(* already have this for naturals, div_mult_self1/2, but not for ints *)
lemma zdiv_mult_self: "m ~= (0 :: int) ==> (a + m * n) div m = a div m + n"
apply (rule mcl)
prefer 2
apply (erule asm_rl)
apply (simp add: zmde ring_distribs)
done
lemma mod_power_lem:
"a > 1 ==> a ^ n mod a ^ m = (if m <= n then 0 else (a :: int) ^ n)"
apply clarsimp
apply safe
apply (simp add: dvd_eq_mod_eq_0 [symmetric])
apply (drule le_iff_add [THEN iffD1])
apply (force simp: power_add)
apply (rule mod_pos_pos_trivial)
apply (simp)
apply (rule power_strict_increasing)
apply auto
done
lemma pl_pl_rels:
"a + b = c + d ==>
a >= c & b <= d | a <= c & b >= (d :: nat)" by arith
lemmas pl_pl_rels' = add.commute [THEN [2] trans, THEN pl_pl_rels]
lemma minus_eq: "(m - k = m) = (k = 0 | m = (0 :: nat))" by arith
lemma pl_pl_mm: "(a :: nat) + b = c + d ==> a - c = d - b" by arith
lemmas pl_pl_mm' = add.commute [THEN [2] trans, THEN pl_pl_mm]
lemmas dme = div_mult_mod_eq
lemmas dtle = xtr3 [OF dme [symmetric] le_add1]
lemmas th2 = order_trans [OF order_refl [THEN [2] mult_le_mono] dtle]
lemma td_gal:
"0 < c ==> (a >= b * c) = (a div c >= (b :: nat))"
apply safe
apply (erule (1) xtr4 [OF div_le_mono div_mult_self_is_m])
apply (erule th2)
done
lemmas td_gal_lt = td_gal [simplified not_less [symmetric], simplified]
lemma div_mult_le: "(a :: nat) div b * b <= a"
by (fact dtle)
lemmas sdl = split_div_lemma [THEN iffD1, symmetric]
lemma given_quot: "f > (0 :: nat) ==> (f * l + (f - 1)) div f = l"
by (rule sdl, assumption) (simp (no_asm))
lemma given_quot_alt: "f > (0 :: nat) ==> (l * f + f - Suc 0) div f = l"
apply (frule given_quot)
apply (rule trans)
prefer 2
apply (erule asm_rl)
apply (rule_tac f="%n. n div f" in arg_cong)
apply (simp add : ac_simps)
done
lemma diff_mod_le: "(a::nat) < d ==> b dvd d ==> a - a mod b <= d - b"
apply (unfold dvd_def)
apply clarify
apply (case_tac k)
apply clarsimp
apply clarify
apply (cases "b > 0")
apply (drule mult.commute [THEN xtr1])
apply (frule (1) td_gal_lt [THEN iffD1])
apply (clarsimp simp: le_simps)
apply (rule mult_div_cancel [THEN [2] xtr4])
apply (rule mult_mono)
apply auto
done
lemma less_le_mult':
"w * c < b * c ==> 0 \<le> c ==> (w + 1) * c \<le> b * (c::int)"
apply (rule mult_right_mono)
apply (rule zless_imp_add1_zle)
apply (erule (1) mult_right_less_imp_less)
apply assumption
done
lemma less_le_mult:
"w * c < b * c \<Longrightarrow> 0 \<le> c \<Longrightarrow> w * c + c \<le> b * (c::int)"
using less_le_mult' [of w c b] by (simp add: algebra_simps)
lemmas less_le_mult_minus = iffD2 [OF le_diff_eq less_le_mult,
simplified left_diff_distrib]
lemma gen_minus: "0 < n ==> f n = f (Suc (n - 1))"
by auto
lemma mpl_lem: "j <= (i :: nat) ==> k < j ==> i - j + k < i" by arith
lemma nonneg_mod_div:
"0 <= a ==> 0 <= b ==> 0 <= (a mod b :: int) & 0 <= a div b"
apply (cases "b = 0", clarsimp)
apply (auto intro: pos_imp_zdiv_nonneg_iff [THEN iffD2])
done
declare iszero_0 [intro]
lemma min_pm [simp]:
"min a b + (a - b) = (a :: nat)"
by arith
lemma min_pm1 [simp]:
"a - b + min a b = (a :: nat)"
by arith
lemma rev_min_pm [simp]:
"min b a + (a - b) = (a :: nat)"
by arith
lemma rev_min_pm1 [simp]:
"a - b + min b a = (a :: nat)"
by arith
lemma min_minus [simp]:
"min m (m - k) = (m - k :: nat)"
by arith
lemma min_minus' [simp]:
"min (m - k) m = (m - k :: nat)"
by arith
end