3 Author: Lawrence C Paulson, Cambridge University Computer Laboratory
4 Copyright 1996 University of Cambridge
8 header{*The Integers as Equivalence Classes over Pairs of Natural Numbers*}
10 theory IntDef = Equiv + NatArith:
13 intrel :: "((nat * nat) * (nat * nat)) set"
14 --{*the equivalence relation underlying the integers*}
15 "intrel == {((x,y),(u,v)) | x y u v. x+v = u+y}"
19 by (auto simp add: quotient_def)
21 instance int :: "{ord, zero, one, plus, times, minus}" ..
25 "int m == Abs_Integ(intrel `` {(m,0)})"
30 Zero_int_def: "0 == int 0"
31 One_int_def: "1 == int 1"
34 "- z == Abs_Integ (\<Union>(x,y) \<in> Rep_Integ z. intrel``{(y,x)})"
38 Abs_Integ (\<Union>(x,y) \<in> Rep_Integ z. \<Union>(u,v) \<in> Rep_Integ w.
39 intrel``{(x+u, y+v)})"
41 diff_int_def: "z - (w::int) == z + (-w)"
45 Abs_Integ (\<Union>(x,y) \<in> Rep_Integ z. \<Union>(u,v) \<in> Rep_Integ w.
46 intrel``{(x*u + y*v, x*v + y*u)})"
50 \<exists>x y u v. x+v \<le> u+y & (x,y) \<in> Rep_Integ z & (u,v) \<in> Rep_Integ w"
52 less_int_def: "(z < (w::int)) == (z \<le> w & z \<noteq> w)"
55 subsection{*Construction of the Integers*}
57 subsubsection{*Preliminary Lemmas about the Equivalence Relation*}
59 lemma intrel_iff [simp]: "(((x,y),(u,v)) \<in> intrel) = (x+v = u+y)"
60 by (simp add: intrel_def)
62 lemma equiv_intrel: "equiv UNIV intrel"
63 by (simp add: intrel_def equiv_def refl_def sym_def trans_def)
65 text{*Reduces equality of equivalence classes to the @{term intrel} relation:
66 @{term "(intrel `` {x} = intrel `` {y}) = ((x,y) \<in> intrel)"} *}
67 lemmas equiv_intrel_iff = eq_equiv_class_iff [OF equiv_intrel UNIV_I UNIV_I]
69 declare equiv_intrel_iff [simp]
72 text{*All equivalence classes belong to set of representatives*}
73 lemma [simp]: "intrel``{(x,y)} \<in> Integ"
74 by (auto simp add: Integ_def intrel_def quotient_def)
76 lemma inj_on_Abs_Integ: "inj_on Abs_Integ Integ"
77 apply (rule inj_on_inverseI)
78 apply (erule Abs_Integ_inverse)
81 text{*This theorem reduces equality on abstractions to equality on
83 @{term "\<lbrakk>x \<in> Integ; y \<in> Integ\<rbrakk> \<Longrightarrow> (Abs_Integ x = Abs_Integ y) = (x=y)"} *}
84 declare inj_on_Abs_Integ [THEN inj_on_iff, simp]
86 declare Abs_Integ_inverse [simp]
88 text{*Case analysis on the representation of an integer as an equivalence
89 class of pairs of naturals.*}
90 lemma eq_Abs_Integ [case_names Abs_Integ, cases type: int]:
91 "(!!x y. z = Abs_Integ(intrel``{(x,y)}) ==> P) ==> P"
92 apply (rule Rep_Integ [of z, unfolded Integ_def, THEN quotientE])
93 apply (drule arg_cong [where f=Abs_Integ])
94 apply (auto simp add: Rep_Integ_inverse)
98 subsubsection{*@{term int}: Embedding the Naturals into the Integers*}
100 lemma inj_int: "inj int"
101 by (simp add: inj_on_def int_def)
103 lemma int_int_eq [iff]: "(int m = int n) = (m = n)"
104 by (fast elim!: inj_int [THEN injD])
107 subsubsection{*Integer Unary Negation*}
109 lemma minus: "- Abs_Integ(intrel``{(x,y)}) = Abs_Integ(intrel `` {(y,x)})"
111 have "congruent intrel (\<lambda>(x,y). intrel``{(y,x)})"
112 by (simp add: congruent_def)
114 by (simp add: minus_int_def UN_equiv_class [OF equiv_intrel])
117 lemma zminus_zminus: "- (- z) = (z::int)"
118 by (cases z, simp add: minus)
120 lemma zminus_0: "- 0 = (0::int)"
121 by (simp add: int_def Zero_int_def minus)
124 subsection{*Integer Addition*}
127 "Abs_Integ (intrel``{(x,y)}) + Abs_Integ (intrel``{(u,v)}) =
128 Abs_Integ (intrel``{(x+u, y+v)})"
130 have "congruent2 intrel intrel
131 (\<lambda>z w. (\<lambda>(x,y). (\<lambda>(u,v). intrel `` {(x+u, y+v)}) w) z)"
132 by (simp add: congruent2_def)
134 by (simp add: add_int_def UN_UN_split_split_eq
135 UN_equiv_class2 [OF equiv_intrel equiv_intrel])
138 lemma zminus_zadd_distrib: "- (z + w) = (- z) + (- w::int)"
139 by (cases z, cases w, simp add: minus add)
141 lemma zadd_commute: "(z::int) + w = w + z"
142 by (cases z, cases w, simp add: add_ac add)
144 lemma zadd_assoc: "((z1::int) + z2) + z3 = z1 + (z2 + z3)"
145 by (cases z1, cases z2, cases z3, simp add: add add_assoc)
148 lemma zadd_left_commute: "x + (y + z) = y + ((x + z) ::int)"
149 apply (rule mk_left_commute [of "op +"])
150 apply (rule zadd_assoc)
151 apply (rule zadd_commute)
154 lemmas zadd_ac = zadd_assoc zadd_commute zadd_left_commute
156 lemmas zmult_ac = OrderedGroup.mult_ac
158 lemma zadd_int: "(int m) + (int n) = int (m + n)"
159 by (simp add: int_def add)
161 lemma zadd_int_left: "(int m) + (int n + z) = int (m + n) + z"
162 by (simp add: zadd_int zadd_assoc [symmetric])
164 lemma int_Suc: "int (Suc m) = 1 + (int m)"
165 by (simp add: One_int_def zadd_int)
167 (*also for the instance declaration int :: comm_monoid_add*)
168 lemma zadd_0: "(0::int) + z = z"
169 apply (simp add: Zero_int_def int_def)
170 apply (cases z, simp add: add)
173 lemma zadd_0_right: "z + (0::int) = z"
174 by (rule trans [OF zadd_commute zadd_0])
176 lemma zadd_zminus_inverse2: "(- z) + z = (0::int)"
177 by (cases z, simp add: int_def Zero_int_def minus add)
180 subsection{*Integer Multiplication*}
182 text{*Congruence property for multiplication*}
183 lemma mult_congruent2:
184 "congruent2 intrel intrel
185 (%p1 p2. (%(x,y). (%(u,v).
186 intrel``{(x*u + y*v, x*v + y*u)}) p2) p1)"
187 apply (rule equiv_intrel [THEN congruent2_commuteI])
188 apply (force simp add: mult_ac, clarify)
189 apply (simp add: congruent_def mult_ac)
190 apply (rename_tac u v w x y z)
191 apply (subgoal_tac "u*y + x*y = w*y + v*y & u*z + x*z = w*z + v*z")
192 apply (simp add: mult_ac, arith)
193 apply (simp add: add_mult_distrib [symmetric])
198 "Abs_Integ((intrel``{(x,y)})) * Abs_Integ((intrel``{(u,v)})) =
199 Abs_Integ(intrel `` {(x*u + y*v, x*v + y*u)})"
200 by (simp add: mult_int_def UN_UN_split_split_eq mult_congruent2
201 UN_equiv_class2 [OF equiv_intrel equiv_intrel])
203 lemma zmult_zminus: "(- z) * w = - (z * (w::int))"
204 by (cases z, cases w, simp add: minus mult add_ac)
206 lemma zmult_commute: "(z::int) * w = w * z"
207 by (cases z, cases w, simp add: mult add_ac mult_ac)
209 lemma zmult_assoc: "((z1::int) * z2) * z3 = z1 * (z2 * z3)"
210 by (cases z1, cases z2, cases z3, simp add: mult add_mult_distrib2 mult_ac)
212 lemma zadd_zmult_distrib: "((z1::int) + z2) * w = (z1 * w) + (z2 * w)"
213 by (cases z1, cases z2, cases w, simp add: add mult add_mult_distrib2 mult_ac)
215 lemma zadd_zmult_distrib2: "(w::int) * (z1 + z2) = (w * z1) + (w * z2)"
216 by (simp add: zmult_commute [of w] zadd_zmult_distrib)
218 lemma zdiff_zmult_distrib: "((z1::int) - z2) * w = (z1 * w) - (z2 * w)"
219 by (simp add: diff_int_def zadd_zmult_distrib zmult_zminus)
221 lemma zdiff_zmult_distrib2: "(w::int) * (z1 - z2) = (w * z1) - (w * z2)"
222 by (simp add: zmult_commute [of w] zdiff_zmult_distrib)
225 zadd_zmult_distrib zadd_zmult_distrib2
226 zdiff_zmult_distrib zdiff_zmult_distrib2
228 lemma zmult_int: "(int m) * (int n) = int (m * n)"
229 by (simp add: int_def mult)
231 lemma zmult_1: "(1::int) * z = z"
232 by (cases z, simp add: One_int_def int_def mult)
234 lemma zmult_1_right: "z * (1::int) = z"
235 by (rule trans [OF zmult_commute zmult_1])
238 text{*The Integers Form A comm_ring_1*}
239 instance int :: comm_ring_1
242 show "(i + j) + k = i + (j + k)" by (simp add: zadd_assoc)
243 show "i + j = j + i" by (simp add: zadd_commute)
244 show "0 + i = i" by (rule zadd_0)
245 show "- i + i = 0" by (rule zadd_zminus_inverse2)
246 show "i - j = i + (-j)" by (simp add: diff_int_def)
247 show "(i * j) * k = i * (j * k)" by (rule zmult_assoc)
248 show "i * j = j * i" by (rule zmult_commute)
249 show "1 * i = i" by (rule zmult_1)
250 show "(i + j) * k = i * k + j * k" by (simp add: int_distrib)
251 show "0 \<noteq> (1::int)"
252 by (simp only: Zero_int_def One_int_def One_nat_def int_int_eq)
256 subsection{*The @{text "\<le>"} Ordering*}
259 "(Abs_Integ(intrel``{(x,y)}) \<le> Abs_Integ(intrel``{(u,v)})) = (x+v \<le> u+y)"
260 by (force simp add: le_int_def)
262 lemma zle_refl: "w \<le> (w::int)"
263 by (cases w, simp add: le)
265 lemma zle_trans: "[| i \<le> j; j \<le> k |] ==> i \<le> (k::int)"
266 by (cases i, cases j, cases k, simp add: le)
268 lemma zle_anti_sym: "[| z \<le> w; w \<le> z |] ==> z = (w::int)"
269 by (cases w, cases z, simp add: le)
271 (* Axiom 'order_less_le' of class 'order': *)
272 lemma zless_le: "((w::int) < z) = (w \<le> z & w \<noteq> z)"
273 by (simp add: less_int_def)
275 instance int :: order
278 rule zle_refl zle_trans zle_anti_sym zless_le)+
280 (* Axiom 'linorder_linear' of class 'linorder': *)
281 lemma zle_linear: "(z::int) \<le> w | w \<le> z"
282 by (cases z, cases w) (simp add: le linorder_linear)
284 instance int :: linorder
285 by intro_classes (rule zle_linear)
288 lemmas zless_linear = linorder_less_linear [where 'a = int]
291 lemma int_eq_0_conv [simp]: "(int n = 0) = (n = 0)"
292 by (simp add: Zero_int_def)
294 lemma zless_int [simp]: "(int m < int n) = (m<n)"
295 by (simp add: le add int_def linorder_not_le [symmetric])
297 lemma int_less_0_conv [simp]: "~ (int k < 0)"
298 by (simp add: Zero_int_def)
300 lemma zero_less_int_conv [simp]: "(0 < int n) = (0 < n)"
301 by (simp add: Zero_int_def)
303 lemma int_0_less_1: "0 < (1::int)"
304 by (simp only: Zero_int_def One_int_def One_nat_def zless_int)
306 lemma int_0_neq_1 [simp]: "0 \<noteq> (1::int)"
307 by (simp only: Zero_int_def One_int_def One_nat_def int_int_eq)
309 lemma zle_int [simp]: "(int m \<le> int n) = (m\<le>n)"
310 by (simp add: linorder_not_less [symmetric])
312 lemma zero_zle_int [simp]: "(0 \<le> int n)"
313 by (simp add: Zero_int_def)
315 lemma int_le_0_conv [simp]: "(int n \<le> 0) = (n = 0)"
316 by (simp add: Zero_int_def)
318 lemma int_0 [simp]: "int 0 = (0::int)"
319 by (simp add: Zero_int_def)
321 lemma int_1 [simp]: "int 1 = 1"
322 by (simp add: One_int_def)
324 lemma int_Suc0_eq_1: "int (Suc 0) = 1"
325 by (simp add: One_int_def One_nat_def)
328 subsection{*Monotonicity results*}
330 lemma zadd_left_mono: "i \<le> j ==> k + i \<le> k + (j::int)"
331 by (cases i, cases j, cases k, simp add: le add)
333 lemma zadd_strict_right_mono: "i < j ==> i + k < j + (k::int)"
334 apply (cases i, cases j, cases k)
335 apply (simp add: linorder_not_le [where 'a = int, symmetric]
336 linorder_not_le [where 'a = nat] le add)
339 lemma zadd_zless_mono: "[| w'<w; z'\<le>z |] ==> w' + z' < w + (z::int)"
340 by (rule order_less_le_trans [OF zadd_strict_right_mono zadd_left_mono])
343 subsection{*Strict Monotonicity of Multiplication*}
345 text{*strict, in 1st argument; proof is by induction on k>0*}
346 lemma zmult_zless_mono2_lemma [rule_format]:
347 "i<j ==> 0<k --> int k * i < int k * j"
348 apply (induct_tac "k", simp)
349 apply (simp add: int_Suc)
350 apply (case_tac "n=0")
351 apply (simp_all add: zadd_zmult_distrib int_Suc0_eq_1 order_le_less)
352 apply (simp add: zadd_zless_mono int_Suc0_eq_1 order_le_less)
355 lemma zero_le_imp_eq_int: "0 \<le> k ==> \<exists>n. k = int n"
357 apply (auto simp add: le add int_def Zero_int_def)
358 apply (rule_tac x="x-y" in exI, simp)
361 lemma zmult_zless_mono2: "[| i<j; (0::int) < k |] ==> k*i < k*j"
362 apply (frule order_less_imp_le [THEN zero_le_imp_eq_int])
363 apply (auto simp add: zmult_zless_mono2_lemma)
368 zabs_def: "abs(i::int) == if i < 0 then -i else i"
371 text{*The Integers Form an Ordered comm_ring_1*}
372 instance int :: ordered_idom
375 show "i \<le> j ==> k + i \<le> k + j" by (rule zadd_left_mono)
376 show "i < j ==> 0 < k ==> k * i < k * j" by (rule zmult_zless_mono2)
377 show "\<bar>i\<bar> = (if i < 0 then -i else i)" by (simp only: zabs_def)
381 lemma zless_imp_add1_zle: "w<z ==> w + (1::int) \<le> z"
382 apply (cases w, cases z)
383 apply (simp add: linorder_not_le [symmetric] le int_def add One_int_def)
386 subsection{*Magnitide of an Integer, as a Natural Number: @{term nat}*}
390 "nat z == contents (\<Union>(x,y) \<in> Rep_Integ z. { x-y })"
392 lemma nat: "nat (Abs_Integ (intrel``{(x,y)})) = x-y"
394 have "congruent intrel (\<lambda>(x,y). {x-y})"
395 by (simp add: congruent_def, arith)
397 by (simp add: nat_def UN_equiv_class [OF equiv_intrel])
400 lemma nat_int [simp]: "nat(int n) = n"
401 by (simp add: nat int_def)
403 lemma nat_zero [simp]: "nat 0 = 0"
404 by (simp only: Zero_int_def nat_int)
406 lemma int_nat_eq [simp]: "int (nat z) = (if 0 \<le> z then z else 0)"
407 by (cases z, simp add: nat le int_def Zero_int_def)
409 corollary nat_0_le: "0 \<le> z ==> int (nat z) = z"
413 lemma nat_le_0 [simp]: "z \<le> 0 ==> nat z = 0"
414 by (cases z, simp add: nat le int_def Zero_int_def)
416 lemma nat_le_eq_zle: "0 < w | 0 \<le> z ==> (nat w \<le> nat z) = (w\<le>z)"
417 apply (cases w, cases z)
418 apply (simp add: nat le linorder_not_le [symmetric] int_def Zero_int_def, arith)
421 text{*An alternative condition is @{term "0 \<le> w"} *}
422 corollary nat_mono_iff: "0 < z ==> (nat w < nat z) = (w < z)"
423 by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
425 corollary nat_less_eq_zless: "0 \<le> w ==> (nat w < nat z) = (w<z)"
426 by (simp add: nat_le_eq_zle linorder_not_le [symmetric])
428 lemma zless_nat_conj: "(nat w < nat z) = (0 < z & w < z)"
429 apply (cases w, cases z)
430 apply (simp add: nat le int_def Zero_int_def linorder_not_le [symmetric], arith)
433 lemma nonneg_eq_int: "[| 0 \<le> z; !!m. z = int m ==> P |] ==> P"
434 by (blast dest: nat_0_le sym)
436 lemma nat_eq_iff: "(nat w = m) = (if 0 \<le> w then w = int m else m=0)"
437 by (cases w, simp add: nat le int_def Zero_int_def, arith)
439 corollary nat_eq_iff2: "(m = nat w) = (if 0 \<le> w then w = int m else m=0)"
440 by (simp only: eq_commute [of m] nat_eq_iff)
442 lemma nat_less_iff: "0 \<le> w ==> (nat w < m) = (w < int m)"
444 apply (simp add: nat le int_def Zero_int_def linorder_not_le [symmetric], arith)
447 lemma int_eq_iff: "(int m = z) = (m = nat z & 0 \<le> z)"
448 by (auto simp add: nat_eq_iff2)
450 lemma zero_less_nat_eq [simp]: "(0 < nat z) = (0 < z)"
451 by (insert zless_nat_conj [of 0], auto)
454 lemma nat_add_distrib:
455 "[| (0::int) \<le> z; 0 \<le> z' |] ==> nat (z+z') = nat z + nat z'"
456 by (cases z, cases z', simp add: nat add le int_def Zero_int_def)
458 lemma nat_diff_distrib:
459 "[| (0::int) \<le> z'; z' \<le> z |] ==> nat (z-z') = nat z - nat z'"
460 by (cases z, cases z',
461 simp add: nat add minus diff_minus le int_def Zero_int_def)
464 lemma nat_zminus_int [simp]: "nat (- (int n)) = 0"
465 by (simp add: int_def minus nat Zero_int_def)
467 lemma zless_nat_eq_int_zless: "(m < nat z) = (int m < z)"
468 by (cases z, simp add: nat le int_def linorder_not_le [symmetric], arith)
471 subsection{*Lemmas about the Function @{term int} and Orderings*}
473 lemma negative_zless_0: "- (int (Suc n)) < 0"
474 by (simp add: order_less_le)
476 lemma negative_zless [iff]: "- (int (Suc n)) < int m"
477 by (rule negative_zless_0 [THEN order_less_le_trans], simp)
479 lemma negative_zle_0: "- int n \<le> 0"
480 by (simp add: minus_le_iff)
482 lemma negative_zle [iff]: "- int n \<le> int m"
483 by (rule order_trans [OF negative_zle_0 zero_zle_int])
485 lemma not_zle_0_negative [simp]: "~ (0 \<le> - (int (Suc n)))"
486 by (subst le_minus_iff, simp)
488 lemma int_zle_neg: "(int n \<le> - int m) = (n = 0 & m = 0)"
489 by (simp add: int_def le minus Zero_int_def)
491 lemma not_int_zless_negative [simp]: "~ (int n < - int m)"
492 by (simp add: linorder_not_less)
494 lemma negative_eq_positive [simp]: "(- int n = int m) = (n = 0 & m = 0)"
495 by (force simp add: order_eq_iff [of "- int n"] int_zle_neg)
497 lemma zle_iff_zadd: "(w \<le> z) = (\<exists>n. z = w + int n)"
498 apply (cases w, cases z)
499 apply (auto simp add: le add int_def)
500 apply (rename_tac a b c d)
501 apply (rule_tac x="c+b - (a+d)" in exI)
505 lemma abs_int_eq [simp]: "abs (int m) = int m"
506 by (simp add: zabs_def)
508 text{*This version is proved for all ordered rings, not just integers!
509 It is proved here because attribute @{text arith_split} is not available
510 in theory @{text Ring_and_Field}.
511 But is it really better than just rewriting with @{text abs_if}?*}
512 lemma abs_split [arith_split]:
513 "P(abs(a::'a::ordered_idom)) = ((0 \<le> a --> P a) & (a < 0 --> P(-a)))"
514 by (force dest: order_less_le_trans simp add: abs_if linorder_not_less)
518 subsection{*The Constants @{term neg} and @{term iszero}*}
522 neg :: "'a::ordered_idom => bool"
525 (*For simplifying equalities*)
526 iszero :: "'a::comm_semiring_1_cancel => bool"
527 "iszero z == z = (0)"
530 lemma not_neg_int [simp]: "~ neg(int n)"
531 by (simp add: neg_def)
533 lemma neg_zminus_int [simp]: "neg(- (int (Suc n)))"
534 by (simp add: neg_def neg_less_0_iff_less)
536 lemmas neg_eq_less_0 = neg_def
538 lemma not_neg_eq_ge_0: "(~neg x) = (0 \<le> x)"
539 by (simp add: neg_def linorder_not_less)
542 subsection{*To simplify inequalities when Numeral1 can get simplified to 1*}
544 lemma not_neg_0: "~ neg 0"
545 by (simp add: One_int_def neg_def)
547 lemma not_neg_1: "~ neg 1"
548 by (simp add: neg_def linorder_not_less zero_le_one)
550 lemma iszero_0: "iszero 0"
551 by (simp add: iszero_def)
553 lemma not_iszero_1: "~ iszero 1"
554 by (simp add: iszero_def eq_commute)
556 lemma neg_nat: "neg z ==> nat z = 0"
557 by (simp add: neg_def order_less_imp_le)
559 lemma not_neg_nat: "~ neg z ==> int (nat z) = z"
560 by (simp add: linorder_not_less neg_def)
563 subsection{*Embedding of the Naturals into any comm_semiring_1_cancel: @{term of_nat}*}
565 consts of_nat :: "nat => 'a::comm_semiring_1_cancel"
568 of_nat_0: "of_nat 0 = 0"
569 of_nat_Suc: "of_nat (Suc m) = of_nat m + 1"
571 lemma of_nat_1 [simp]: "of_nat 1 = 1"
574 lemma of_nat_add [simp]: "of_nat (m+n) = of_nat m + of_nat n"
576 apply (simp_all add: add_ac)
579 lemma of_nat_mult [simp]: "of_nat (m*n) = of_nat m * of_nat n"
581 apply (simp_all add: mult_ac add_ac right_distrib)
584 lemma zero_le_imp_of_nat: "0 \<le> (of_nat m::'a::ordered_semidom)"
585 apply (induct m, simp_all)
586 apply (erule order_trans)
587 apply (rule less_add_one [THEN order_less_imp_le])
590 lemma less_imp_of_nat_less:
591 "m < n ==> of_nat m < (of_nat n::'a::ordered_semidom)"
592 apply (induct m n rule: diff_induct, simp_all)
593 apply (insert add_le_less_mono [OF zero_le_imp_of_nat zero_less_one], force)
596 lemma of_nat_less_imp_less:
597 "of_nat m < (of_nat n::'a::ordered_semidom) ==> m < n"
598 apply (induct m n rule: diff_induct, simp_all)
599 apply (insert zero_le_imp_of_nat)
600 apply (force simp add: linorder_not_less [symmetric])
603 lemma of_nat_less_iff [simp]:
604 "(of_nat m < (of_nat n::'a::ordered_semidom)) = (m<n)"
605 by (blast intro: of_nat_less_imp_less less_imp_of_nat_less)
607 text{*Special cases where either operand is zero*}
608 declare of_nat_less_iff [of 0, simplified, simp]
609 declare of_nat_less_iff [of _ 0, simplified, simp]
611 lemma of_nat_le_iff [simp]:
612 "(of_nat m \<le> (of_nat n::'a::ordered_semidom)) = (m \<le> n)"
613 by (simp add: linorder_not_less [symmetric])
615 text{*Special cases where either operand is zero*}
616 declare of_nat_le_iff [of 0, simplified, simp]
617 declare of_nat_le_iff [of _ 0, simplified, simp]
619 text{*The ordering on the comm_semiring_1_cancel is necessary to exclude the possibility of
620 a finite field, which indeed wraps back to zero.*}
621 lemma of_nat_eq_iff [simp]:
622 "(of_nat m = (of_nat n::'a::ordered_semidom)) = (m = n)"
623 by (simp add: order_eq_iff)
625 text{*Special cases where either operand is zero*}
626 declare of_nat_eq_iff [of 0, simplified, simp]
627 declare of_nat_eq_iff [of _ 0, simplified, simp]
629 lemma of_nat_diff [simp]:
630 "n \<le> m ==> of_nat (m - n) = of_nat m - (of_nat n :: 'a::comm_ring_1)"
631 by (simp del: of_nat_add
632 add: compare_rls of_nat_add [symmetric] split add: nat_diff_split)
635 subsection{*The Set of Natural Numbers*}
638 Nats :: "'a::comm_semiring_1_cancel set"
639 "Nats == range of_nat"
641 syntax (xsymbols) Nats :: "'a set" ("\<nat>")
643 lemma of_nat_in_Nats [simp]: "of_nat n \<in> Nats"
644 by (simp add: Nats_def)
646 lemma Nats_0 [simp]: "0 \<in> Nats"
647 apply (simp add: Nats_def)
648 apply (rule range_eqI)
649 apply (rule of_nat_0 [symmetric])
652 lemma Nats_1 [simp]: "1 \<in> Nats"
653 apply (simp add: Nats_def)
654 apply (rule range_eqI)
655 apply (rule of_nat_1 [symmetric])
658 lemma Nats_add [simp]: "[|a \<in> Nats; b \<in> Nats|] ==> a+b \<in> Nats"
659 apply (auto simp add: Nats_def)
660 apply (rule range_eqI)
661 apply (rule of_nat_add [symmetric])
664 lemma Nats_mult [simp]: "[|a \<in> Nats; b \<in> Nats|] ==> a*b \<in> Nats"
665 apply (auto simp add: Nats_def)
666 apply (rule range_eqI)
667 apply (rule of_nat_mult [symmetric])
670 text{*Agreement with the specific embedding for the integers*}
671 lemma int_eq_of_nat: "int = (of_nat :: nat => int)"
674 show "int n = of_nat n" by (induct n, simp_all add: int_Suc add_ac)
677 lemma of_nat_eq_id [simp]: "of_nat = (id :: nat => nat)"
680 show "of_nat n = id n" by (induct n, simp_all)
684 subsection{*Embedding of the Integers into any comm_ring_1: @{term of_int}*}
687 of_int :: "int => 'a::comm_ring_1"
688 "of_int z == contents (\<Union>(i,j) \<in> Rep_Integ z. { of_nat i - of_nat j })"
691 lemma of_int: "of_int (Abs_Integ (intrel `` {(i,j)})) = of_nat i - of_nat j"
693 have "congruent intrel (\<lambda>(i,j). { of_nat i - (of_nat j :: 'a) })"
694 by (simp add: congruent_def compare_rls of_nat_add [symmetric]
697 by (simp add: of_int_def UN_equiv_class [OF equiv_intrel])
700 lemma of_int_0 [simp]: "of_int 0 = 0"
701 by (simp add: of_int Zero_int_def int_def)
703 lemma of_int_1 [simp]: "of_int 1 = 1"
704 by (simp add: of_int One_int_def int_def)
706 lemma of_int_add [simp]: "of_int (w+z) = of_int w + of_int z"
707 by (cases w, cases z, simp add: compare_rls of_int add)
709 lemma of_int_minus [simp]: "of_int (-z) = - (of_int z)"
710 by (cases z, simp add: compare_rls of_int minus)
712 lemma of_int_diff [simp]: "of_int (w-z) = of_int w - of_int z"
713 by (simp add: diff_minus)
715 lemma of_int_mult [simp]: "of_int (w*z) = of_int w * of_int z"
716 apply (cases w, cases z)
717 apply (simp add: compare_rls of_int left_diff_distrib right_diff_distrib
721 lemma of_int_le_iff [simp]:
722 "(of_int w \<le> (of_int z::'a::ordered_idom)) = (w \<le> z)"
725 apply (simp add: compare_rls of_int le diff_int_def add minus
726 of_nat_add [symmetric] del: of_nat_add)
729 text{*Special cases where either operand is zero*}
730 declare of_int_le_iff [of 0, simplified, simp]
731 declare of_int_le_iff [of _ 0, simplified, simp]
733 lemma of_int_less_iff [simp]:
734 "(of_int w < (of_int z::'a::ordered_idom)) = (w < z)"
735 by (simp add: linorder_not_le [symmetric])
737 text{*Special cases where either operand is zero*}
738 declare of_int_less_iff [of 0, simplified, simp]
739 declare of_int_less_iff [of _ 0, simplified, simp]
741 text{*The ordering on the comm_ring_1 is necessary. See @{text of_nat_eq_iff} above.*}
742 lemma of_int_eq_iff [simp]:
743 "(of_int w = (of_int z::'a::ordered_idom)) = (w = z)"
744 by (simp add: order_eq_iff)
746 text{*Special cases where either operand is zero*}
747 declare of_int_eq_iff [of 0, simplified, simp]
748 declare of_int_eq_iff [of _ 0, simplified, simp]
750 lemma of_int_eq_id [simp]: "of_int = (id :: int => int)"
753 show "of_int z = id z"
755 simp add: of_int add minus int_eq_of_nat [symmetric] int_def diff_minus)
759 subsection{*The Set of Integers*}
762 Ints :: "'a::comm_ring_1 set"
763 "Ints == range of_int"
767 Ints :: "'a set" ("\<int>")
769 lemma Ints_0 [simp]: "0 \<in> Ints"
770 apply (simp add: Ints_def)
771 apply (rule range_eqI)
772 apply (rule of_int_0 [symmetric])
775 lemma Ints_1 [simp]: "1 \<in> Ints"
776 apply (simp add: Ints_def)
777 apply (rule range_eqI)
778 apply (rule of_int_1 [symmetric])
781 lemma Ints_add [simp]: "[|a \<in> Ints; b \<in> Ints|] ==> a+b \<in> Ints"
782 apply (auto simp add: Ints_def)
783 apply (rule range_eqI)
784 apply (rule of_int_add [symmetric])
787 lemma Ints_minus [simp]: "a \<in> Ints ==> -a \<in> Ints"
788 apply (auto simp add: Ints_def)
789 apply (rule range_eqI)
790 apply (rule of_int_minus [symmetric])
793 lemma Ints_diff [simp]: "[|a \<in> Ints; b \<in> Ints|] ==> a-b \<in> Ints"
794 apply (auto simp add: Ints_def)
795 apply (rule range_eqI)
796 apply (rule of_int_diff [symmetric])
799 lemma Ints_mult [simp]: "[|a \<in> Ints; b \<in> Ints|] ==> a*b \<in> Ints"
800 apply (auto simp add: Ints_def)
801 apply (rule range_eqI)
802 apply (rule of_int_mult [symmetric])
805 text{*Collapse nested embeddings*}
806 lemma of_int_of_nat_eq [simp]: "of_int (of_nat n) = of_nat n"
809 lemma of_int_int_eq [simp]: "of_int (int n) = int n"
810 by (simp add: int_eq_of_nat)
813 lemma Ints_cases [case_names of_int, cases set: Ints]:
814 "q \<in> \<int> ==> (!!z. q = of_int z ==> C) ==> C"
815 proof (simp add: Ints_def)
816 assume "!!z. q = of_int z ==> C"
817 assume "q \<in> range of_int" thus C ..
820 lemma Ints_induct [case_names of_int, induct set: Ints]:
821 "q \<in> \<int> ==> (!!z. P (of_int z)) ==> P q"
822 by (rule Ints_cases) auto
825 (* int (Suc n) = 1 + int n *)
826 declare int_Suc [simp]
828 text{*Simplification of @{term "x-y < 0"}, etc.*}
829 declare less_iff_diff_less_0 [symmetric, simp]
830 declare eq_iff_diff_eq_0 [symmetric, simp]
831 declare le_iff_diff_le_0 [symmetric, simp]
834 subsection{*More Properties of @{term setsum} and @{term setprod}*}
836 text{*By Jeremy Avigad*}
839 lemma setsum_of_nat: "of_nat (setsum f A) = setsum (of_nat \<circ> f) A"
840 apply (case_tac "finite A")
841 apply (erule finite_induct, auto)
842 apply (simp add: setsum_def)
845 lemma setsum_of_int: "of_int (setsum f A) = setsum (of_int \<circ> f) A"
846 apply (case_tac "finite A")
847 apply (erule finite_induct, auto)
848 apply (simp add: setsum_def)
851 lemma int_setsum: "int (setsum f A) = setsum (int \<circ> f) A"
852 by (subst int_eq_of_nat, rule setsum_of_nat)
854 lemma setprod_of_nat: "of_nat (setprod f A) = setprod (of_nat \<circ> f) A"
855 apply (case_tac "finite A")
856 apply (erule finite_induct, auto)
857 apply (simp add: setprod_def)
860 lemma setprod_of_int: "of_int (setprod f A) = setprod (of_int \<circ> f) A"
861 apply (case_tac "finite A")
862 apply (erule finite_induct, auto)
863 apply (simp add: setprod_def)
866 lemma int_setprod: "int (setprod f A) = setprod (int \<circ> f) A"
867 by (subst int_eq_of_nat, rule setprod_of_nat)
869 lemma setsum_constant: "finite A ==> (\<Sum>x \<in> A. y) = of_nat(card A) * y"
870 apply (erule finite_induct)
871 apply (auto simp add: ring_distrib add_ac)
874 lemma setprod_nonzero_nat:
875 "finite A ==> (\<forall>x \<in> A. f x \<noteq> (0::nat)) ==> setprod f A \<noteq> 0"
876 by (rule setprod_nonzero, auto)
878 lemma setprod_zero_eq_nat:
879 "finite A ==> (setprod f A = (0::nat)) = (\<exists>x \<in> A. f x = 0)"
880 by (rule setprod_zero_eq, auto)
882 lemma setprod_nonzero_int:
883 "finite A ==> (\<forall>x \<in> A. f x \<noteq> (0::int)) ==> setprod f A \<noteq> 0"
884 by (rule setprod_nonzero, auto)
886 lemma setprod_zero_eq_int:
887 "finite A ==> (setprod f A = (0::int)) = (\<exists>x \<in> A. f x = 0)"
888 by (rule setprod_zero_eq, auto)
891 text{*Now we replace the case analysis rule by a more conventional one:
892 whether an integer is negative or not.*}
894 lemma zless_iff_Suc_zadd:
895 "(w < z) = (\<exists>n. z = w + int(Suc n))"
896 apply (cases z, cases w)
897 apply (auto simp add: le add int_def linorder_not_le [symmetric])
898 apply (rename_tac a b c d)
899 apply (rule_tac x="a+d - Suc(c+b)" in exI)
903 lemma negD: "x<0 ==> \<exists>n. x = - (int (Suc n))"
905 apply (auto simp add: le minus Zero_int_def int_def order_less_le)
906 apply (rule_tac x="y - Suc x" in exI, arith)
909 theorem int_cases [cases type: int, case_names nonneg neg]:
910 "[|!! n. z = int n ==> P; !! n. z = - (int (Suc n)) ==> P |] ==> P"
911 apply (case_tac "z < 0", blast dest!: negD)
912 apply (simp add: linorder_not_less)
913 apply (blast dest: nat_0_le [THEN sym])
916 theorem int_induct [induct type: int, case_names nonneg neg]:
917 "[|!! n. P (int n); !!n. P (- (int (Suc n))) |] ==> P z"
921 (*Legacy ML bindings, but no longer the structure Int.*)
924 val zabs_def = thm "zabs_def"
926 val int_0 = thm "int_0";
927 val int_1 = thm "int_1";
928 val int_Suc0_eq_1 = thm "int_Suc0_eq_1";
929 val neg_eq_less_0 = thm "neg_eq_less_0";
930 val not_neg_eq_ge_0 = thm "not_neg_eq_ge_0";
931 val not_neg_0 = thm "not_neg_0";
932 val not_neg_1 = thm "not_neg_1";
933 val iszero_0 = thm "iszero_0";
934 val not_iszero_1 = thm "not_iszero_1";
935 val int_0_less_1 = thm "int_0_less_1";
936 val int_0_neq_1 = thm "int_0_neq_1";
937 val negative_zless = thm "negative_zless";
938 val negative_zle = thm "negative_zle";
939 val not_zle_0_negative = thm "not_zle_0_negative";
940 val not_int_zless_negative = thm "not_int_zless_negative";
941 val negative_eq_positive = thm "negative_eq_positive";
942 val zle_iff_zadd = thm "zle_iff_zadd";
943 val abs_int_eq = thm "abs_int_eq";
944 val abs_split = thm"abs_split";
945 val nat_int = thm "nat_int";
946 val nat_zminus_int = thm "nat_zminus_int";
947 val nat_zero = thm "nat_zero";
948 val not_neg_nat = thm "not_neg_nat";
949 val neg_nat = thm "neg_nat";
950 val zless_nat_eq_int_zless = thm "zless_nat_eq_int_zless";
951 val nat_0_le = thm "nat_0_le";
952 val nat_le_0 = thm "nat_le_0";
953 val zless_nat_conj = thm "zless_nat_conj";
954 val int_cases = thm "int_cases";
956 val int_def = thm "int_def";
957 val Zero_int_def = thm "Zero_int_def";
958 val One_int_def = thm "One_int_def";
959 val diff_int_def = thm "diff_int_def";
961 val inj_int = thm "inj_int";
962 val zminus_zminus = thm "zminus_zminus";
963 val zminus_0 = thm "zminus_0";
964 val zminus_zadd_distrib = thm "zminus_zadd_distrib";
965 val zadd_commute = thm "zadd_commute";
966 val zadd_assoc = thm "zadd_assoc";
967 val zadd_left_commute = thm "zadd_left_commute";
968 val zadd_ac = thms "zadd_ac";
969 val zmult_ac = thms "zmult_ac";
970 val zadd_int = thm "zadd_int";
971 val zadd_int_left = thm "zadd_int_left";
972 val int_Suc = thm "int_Suc";
973 val zadd_0 = thm "zadd_0";
974 val zadd_0_right = thm "zadd_0_right";
975 val zmult_zminus = thm "zmult_zminus";
976 val zmult_commute = thm "zmult_commute";
977 val zmult_assoc = thm "zmult_assoc";
978 val zadd_zmult_distrib = thm "zadd_zmult_distrib";
979 val zadd_zmult_distrib2 = thm "zadd_zmult_distrib2";
980 val zdiff_zmult_distrib = thm "zdiff_zmult_distrib";
981 val zdiff_zmult_distrib2 = thm "zdiff_zmult_distrib2";
982 val int_distrib = thms "int_distrib";
983 val zmult_int = thm "zmult_int";
984 val zmult_1 = thm "zmult_1";
985 val zmult_1_right = thm "zmult_1_right";
986 val int_int_eq = thm "int_int_eq";
987 val int_eq_0_conv = thm "int_eq_0_conv";
988 val zless_int = thm "zless_int";
989 val int_less_0_conv = thm "int_less_0_conv";
990 val zero_less_int_conv = thm "zero_less_int_conv";
991 val zle_int = thm "zle_int";
992 val zero_zle_int = thm "zero_zle_int";
993 val int_le_0_conv = thm "int_le_0_conv";
994 val zle_refl = thm "zle_refl";
995 val zle_linear = thm "zle_linear";
996 val zle_trans = thm "zle_trans";
997 val zle_anti_sym = thm "zle_anti_sym";
999 val Ints_def = thm "Ints_def";
1000 val Nats_def = thm "Nats_def";
1002 val of_nat_0 = thm "of_nat_0";
1003 val of_nat_Suc = thm "of_nat_Suc";
1004 val of_nat_1 = thm "of_nat_1";
1005 val of_nat_add = thm "of_nat_add";
1006 val of_nat_mult = thm "of_nat_mult";
1007 val zero_le_imp_of_nat = thm "zero_le_imp_of_nat";
1008 val less_imp_of_nat_less = thm "less_imp_of_nat_less";
1009 val of_nat_less_imp_less = thm "of_nat_less_imp_less";
1010 val of_nat_less_iff = thm "of_nat_less_iff";
1011 val of_nat_le_iff = thm "of_nat_le_iff";
1012 val of_nat_eq_iff = thm "of_nat_eq_iff";
1013 val Nats_0 = thm "Nats_0";
1014 val Nats_1 = thm "Nats_1";
1015 val Nats_add = thm "Nats_add";
1016 val Nats_mult = thm "Nats_mult";
1017 val int_eq_of_nat = thm"int_eq_of_nat";
1018 val of_int = thm "of_int";
1019 val of_int_0 = thm "of_int_0";
1020 val of_int_1 = thm "of_int_1";
1021 val of_int_add = thm "of_int_add";
1022 val of_int_minus = thm "of_int_minus";
1023 val of_int_diff = thm "of_int_diff";
1024 val of_int_mult = thm "of_int_mult";
1025 val of_int_le_iff = thm "of_int_le_iff";
1026 val of_int_less_iff = thm "of_int_less_iff";
1027 val of_int_eq_iff = thm "of_int_eq_iff";
1028 val Ints_0 = thm "Ints_0";
1029 val Ints_1 = thm "Ints_1";
1030 val Ints_add = thm "Ints_add";
1031 val Ints_minus = thm "Ints_minus";
1032 val Ints_diff = thm "Ints_diff";
1033 val Ints_mult = thm "Ints_mult";
1034 val of_int_of_nat_eq = thm"of_int_of_nat_eq";
1035 val Ints_cases = thm "Ints_cases";
1036 val Ints_induct = thm "Ints_induct";