author  paulson 
Tue, 24 Sep 1996 13:54:27 +0200  
changeset 2022  9d47e2962edd 
parent 1984  5cf82dc3ce67 
child 2031  03a843f0f447 
permissions  rwrr 
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(* Title: HOL/simpdata.ML 
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ID: $Id$ 
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Author: Tobias Nipkow 
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Copyright 1991 University of Cambridge 
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Instantiation of the generic simplifier 

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*) 

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1984  9 
section "Simplifier"; 
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923  11 
open Simplifier; 
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1922  13 
(*** Integration of simplifier with classical reasoner ***) 
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(*Add a simpset to a classical set!*) 

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infix 4 addss; 

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fun cs addss ss = cs addbefore asm_full_simp_tac ss 1; 

18 

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fun Addss ss = (claset := !claset addbefore asm_full_simp_tac ss 1); 

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(*Designed to be idempotent, except if best_tac instantiates variables 
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in some of the subgoals*) 
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fun auto_tac (cs,ss) = 
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ALLGOALS (asm_full_simp_tac ss) THEN 

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REPEAT (safe_tac cs THEN ALLGOALS (asm_full_simp_tac ss)) THEN 
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REPEAT (FIRSTGOAL (best_tac (cs addss ss))); 
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28 
fun Auto_tac() = auto_tac (!claset, !simpset); 

29 

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fun auto() = by (Auto_tac()); 

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1984  33 
(*** Addition of rules to simpsets and clasets simultaneously ***) 
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(*Takes UNCONDITIONAL theorems of the form A<>B to 

36 
the Safe Intr rule B==>A and 

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the Safe Destruct rule A==>B. 

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Also ~A goes to the Safe Elim rule A ==> ?R 

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Failing other cases, A is added as a Safe Intr rule*) 

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local 

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val iff_const = HOLogic.eq_const HOLogic.boolT; 

42 

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fun addIff th = 

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(case HOLogic.dest_Trueprop (#prop(rep_thm th)) of 

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(Const("not",_) $ A) => 

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AddSEs [zero_var_indexes (th RS notE)] 

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 (con $ _ $ _) => 

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if con=iff_const 

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then (AddSIs [zero_var_indexes (th RS iffD2)]; 

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AddSDs [zero_var_indexes (th RS iffD1)]) 

51 
else AddSIs [th] 

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 _ => AddSIs [th]; 

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Addsimps [th]) 

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handle _ => error ("AddIffs: theorem must be unconditional\n" ^ 

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string_of_thm th) 

56 

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fun delIff th = 

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(case HOLogic.dest_Trueprop (#prop(rep_thm th)) of 

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(Const("not",_) $ A) => 

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Delrules [zero_var_indexes (th RS notE)] 

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 (con $ _ $ _) => 

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if con=iff_const 

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then Delrules [zero_var_indexes (th RS iffD2), 

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zero_var_indexes (th RS iffD1)] 

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else Delrules [th] 

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 _ => Delrules [th]; 

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Delsimps [th]) 

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handle _ => warning("DelIffs: ignoring conditional theorem\n" ^ 

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string_of_thm th) 

70 
in 

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val AddIffs = seq addIff 

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val DelIffs = seq delIff 

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end; 

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local 
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1922  78 
fun prover s = prove_goal HOL.thy s (fn _ => [fast_tac HOL_cs 1]); 
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1922  80 
val P_imp_P_iff_True = prover "P > (P = True)" RS mp; 
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val P_imp_P_eq_True = P_imp_P_iff_True RS eq_reflection; 

923  82 

1922  83 
val not_P_imp_P_iff_F = prover "~P > (P = False)" RS mp; 
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val not_P_imp_P_eq_False = not_P_imp_P_iff_F RS eq_reflection; 

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1922  86 
fun atomize pairs = 
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let fun atoms th = 

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(case concl_of th of 

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Const("Trueprop",_) $ p => 

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(case head_of p of 

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Const(a,_) => 

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(case assoc(pairs,a) of 

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Some(rls) => flat (map atoms ([th] RL rls)) 

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 None => [th]) 

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 _ => [th]) 

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 _ => [th]) 

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in atoms end; 

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1922  99 
fun mk_meta_eq r = case concl_of r of 
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Const("==",_)$_$_ => r 

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 _$(Const("op =",_)$_$_) => r RS eq_reflection 

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 _$(Const("not",_)$_) => r RS not_P_imp_P_eq_False 

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 _ => r RS P_imp_P_eq_True; 

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(* last 2 lines requires all formulae to be of the from Trueprop(.) *) 

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1922  106 
fun gen_all th = forall_elim_vars (#maxidx(rep_thm th)+1) th; 
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1922  108 
val simp_thms = map prover 
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[ "(x=x) = True", 

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"(~True) = False", "(~False) = True", "(~ ~ P) = P", 

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"(~P) ~= P", "P ~= (~P)", "(P ~= Q) = (P = (~Q))", 

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"(True=P) = P", "(P=True) = P", 

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"(True > P) = P", "(False > P) = True", 

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"(P > True) = True", "(P > P) = True", 

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"(P > False) = (~P)", "(P > ~P) = (~P)", 

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"(P & True) = P", "(True & P) = P", 

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"(P & False) = False", "(False & P) = False", "(P & P) = P", 

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"(P  True) = True", "(True  P) = True", 

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"(P  False) = P", "(False  P) = P", "(P  P) = P", 

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"((~P) = (~Q)) = (P=Q)", 
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"(!x.P) = P", "(? x.P) = P", "? x. x=t", 
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"(? x. x=t & P(x)) = P(t)", "(! x. x=t > P(x)) = P(t)" ]; 

923  123 

124 
in 

125 

126 
val meta_eq_to_obj_eq = prove_goal HOL.thy "x==y ==> x=y" 

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(fn [prem] => [rewtac prem, rtac refl 1]); 

128 

129 
val eq_sym_conv = prover "(x=y) = (y=x)"; 

130 

131 
val conj_assoc = prover "((P&Q)&R) = (P&(Q&R))"; 

132 

1922  133 
val disj_assoc = prover "((PQ)R) = (P(QR))"; 
134 

135 
val imp_disj = prover "(PQ > R) = ((P>R)&(Q>R))"; 

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(*Avoids duplication of subgoals after expand_if, when the true and false 
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cases boil down to the same thing.*) 
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val cases_simp = prover "((P > Q) & (~P > Q)) = Q"; 
1922  140 

965  141 
val if_True = prove_goalw HOL.thy [if_def] "(if True then x else y) = x" 
923  142 
(fn _=>[fast_tac (HOL_cs addIs [select_equality]) 1]); 
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965  144 
val if_False = prove_goalw HOL.thy [if_def] "(if False then x else y) = y" 
923  145 
(fn _=>[fast_tac (HOL_cs addIs [select_equality]) 1]); 
146 

965  147 
val if_P = prove_goal HOL.thy "P ==> (if P then x else y) = x" 
923  148 
(fn [prem] => [ stac (prem RS eqTrueI) 1, rtac if_True 1 ]); 
149 

965  150 
val if_not_P = prove_goal HOL.thy "~P ==> (if P then x else y) = y" 
923  151 
(fn [prem] => [ stac (prem RS not_P_imp_P_iff_F) 1, rtac if_False 1 ]); 
152 

153 
val expand_if = prove_goal HOL.thy 

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"P(if Q then x else y) = ((Q > P(x)) & (~Q > P(y)))" 
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(fn _=> [ (res_inst_tac [("Q","Q")] (excluded_middle RS disjE) 1), 
1465  156 
rtac (if_P RS ssubst) 2, 
157 
rtac (if_not_P RS ssubst) 1, 

158 
REPEAT(fast_tac HOL_cs 1) ]); 

923  159 

965  160 
val if_bool_eq = prove_goal HOL.thy 
161 
"(if P then Q else R) = ((P>Q) & (~P>R))" 

162 
(fn _ => [rtac expand_if 1]); 

923  163 

988  164 
(*Add congruence rules for = (instead of ==) *) 
165 
infix 4 addcongs; 

923  166 
fun ss addcongs congs = ss addeqcongs (congs RL [eq_reflection]); 
167 

1264  168 
fun Addcongs congs = (simpset := !simpset addcongs congs); 
169 

923  170 
val mksimps_pairs = 
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[("op >", [mp]), ("op &", [conjunct1,conjunct2]), 

172 
("All", [spec]), ("True", []), ("False", []), 

965  173 
("If", [if_bool_eq RS iffD1])]; 
923  174 

175 
fun mksimps pairs = map mk_meta_eq o atomize pairs o gen_all; 

176 

1922  177 
val imp_cong = impI RSN 
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(2, prove_goal HOL.thy "(P=P')> (P'> (Q=Q'))> ((P>Q) = (P'>Q'))" 

179 
(fn _=> [fast_tac HOL_cs 1]) RS mp RS mp); 

180 

181 
val o_apply = prove_goalw HOL.thy [o_def] "(f o g)(x) = f(g(x))" 

182 
(fn _ => [rtac refl 1]); 

183 

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(*Miniscoping: pushing in existential quantifiers*) 
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val ex_simps = map prover 
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["(EX x. P x & Q) = ((EX x.P x) & Q)", 
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"(EX x. P & Q x) = (P & (EX x.Q x))", 
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"(EX x. P x  Q) = ((EX x.P x)  Q)", 
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"(EX x. P  Q x) = (P  (EX x.Q x))", 
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"(EX x. P x > Q) = ((ALL x.P x) > Q)", 
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"(EX x. P > Q x) = (P > (EX x.Q x))"]; 
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(*Miniscoping: pushing in universal quantifiers*) 
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val all_simps = map prover 
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["(ALL x. P x & Q) = ((ALL x.P x) & Q)", 
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"(ALL x. P & Q x) = (P & (ALL x.Q x))", 
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"(ALL x. P x  Q) = ((ALL x.P x)  Q)", 
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"(ALL x. P  Q x) = (P  (ALL x.Q x))", 
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"(ALL x. P x > Q) = ((EX x.P x) > Q)", 
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"(ALL x. P > Q x) = (P > (ALL x.Q x))"]; 
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923  202 
val HOL_ss = empty_ss 
203 
setmksimps (mksimps mksimps_pairs) 

204 
setsolver (fn prems => resolve_tac (TrueI::refl::prems) ORELSE' atac 

205 
ORELSE' etac FalseE) 

206 
setsubgoaler asm_simp_tac 

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addsimps ([if_True, if_False, o_apply, imp_disj, conj_assoc, disj_assoc, 
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cases_simp] 
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@ ex_simps @ all_simps @ simp_thms) 
923  210 
addcongs [imp_cong]; 
211 

1922  212 

213 
(*In general it seems wrong to add distributive laws by default: they 

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might cause exponential blowup. But imp_disj has been in for a while 
1922  215 
and cannot be removed without affecting existing proofs. Moreover, 
216 
rewriting by "(PQ > R) = ((P>R)&(Q>R))" might be justified on the 

217 
grounds that it allows simplification of R in the two cases.*) 

218 

219 

941  220 
local val mktac = mk_case_split_tac (meta_eq_to_obj_eq RS iffD2) 
221 
in 

222 
fun split_tac splits = mktac (map mk_meta_eq splits) 

223 
end; 

224 

1722  225 
local val mktac = mk_case_split_inside_tac (meta_eq_to_obj_eq RS iffD2) 
226 
in 

227 
fun split_inside_tac splits = mktac (map mk_meta_eq splits) 

228 
end; 

229 

923  230 

2022  231 
(* elimination of existential quantifiers in assumptions *) 
923  232 

233 
val ex_all_equiv = 

234 
let val lemma1 = prove_goal HOL.thy 

235 
"(? x. P(x) ==> PROP Q) ==> (!!x. P(x) ==> PROP Q)" 

236 
(fn prems => [resolve_tac prems 1, etac exI 1]); 

237 
val lemma2 = prove_goalw HOL.thy [Ex_def] 

238 
"(!!x. P(x) ==> PROP Q) ==> (? x. P(x) ==> PROP Q)" 

239 
(fn prems => [REPEAT(resolve_tac prems 1)]) 

240 
in equal_intr lemma1 lemma2 end; 

241 

242 
(* '&' congruence rule: not included by default! 

243 
May slow rewrite proofs down by as much as 50% *) 

244 

2022  245 
val conj_cong = 
246 
let val th = prove_goal HOL.thy 

247 
"(P=P')> (P'> (Q=Q'))> ((P&Q) = (P'&Q'))" 

248 
(fn _=> [fast_tac HOL_cs 1]) 

249 
in standard (impI RSN (2, th RS mp RS mp)) end; 

923  250 

2022  251 
val rev_conj_cong = 
252 
let val th = prove_goal HOL.thy 

253 
"(Q=Q')> (Q'> (P=P'))> ((P&Q) = (P'&Q'))" 

254 
(fn _=> [fast_tac HOL_cs 1]) 

255 
in standard (impI RSN (2, th RS mp RS mp)) end; 

256 

257 
(* '' congruence rule: not included by default! *) 

258 

259 
val disj_cong = 

260 
let val th = prove_goal HOL.thy 

261 
"(P=P')> (~P'> (Q=Q'))> ((PQ) = (P'Q'))" 

262 
(fn _=> [fast_tac HOL_cs 1]) 

263 
in standard (impI RSN (2, th RS mp RS mp)) end; 

1548  264 

923  265 
(** 'if' congruence rules: neither included by default! *) 
266 

267 
(*Simplifies x assuming c and y assuming ~c*) 

268 
val if_cong = prove_goal HOL.thy 

965  269 
"[ b=c; c ==> x=u; ~c ==> y=v ] ==>\ 
270 
\ (if b then x else y) = (if c then u else v)" 

923  271 
(fn rew::prems => 
272 
[stac rew 1, stac expand_if 1, stac expand_if 1, 

273 
fast_tac (HOL_cs addDs prems) 1]); 

274 

275 
(*Prevents simplification of x and y: much faster*) 

276 
val if_weak_cong = prove_goal HOL.thy 

965  277 
"b=c ==> (if b then x else y) = (if c then x else y)" 
923  278 
(fn [prem] => [rtac (prem RS arg_cong) 1]); 
279 

280 
(*Prevents simplification of t: much faster*) 

281 
val let_weak_cong = prove_goal HOL.thy 

282 
"a = b ==> (let x=a in t(x)) = (let x=b in t(x))" 

283 
(fn [prem] => [rtac (prem RS arg_cong) 1]); 

284 

285 
end; 

286 

287 
fun prove nm thm = qed_goal nm HOL.thy thm (fn _ => [fast_tac HOL_cs 1]); 

288 

289 
prove "conj_commute" "(P&Q) = (Q&P)"; 

290 
prove "conj_left_commute" "(P&(Q&R)) = (Q&(P&R))"; 

291 
val conj_comms = [conj_commute, conj_left_commute]; 

292 

1922  293 
prove "disj_commute" "(PQ) = (QP)"; 
294 
prove "disj_left_commute" "(P(QR)) = (Q(PR))"; 

295 
val disj_comms = [disj_commute, disj_left_commute]; 

296 

923  297 
prove "conj_disj_distribL" "(P&(QR)) = (P&Q  P&R)"; 
298 
prove "conj_disj_distribR" "((PQ)&R) = (P&R  Q&R)"; 

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1892  300 
prove "disj_conj_distribL" "(P(Q&R)) = ((PQ) & (PR))"; 
301 
prove "disj_conj_distribR" "((P&Q)R) = ((PR) & (QR))"; 

302 

303 
prove "imp_conj_distrib" "(P > (Q&R)) = ((P>Q) & (P>R))"; 

1922  304 
prove "imp_conj" "((P&Q)>R) = (P > (Q > R))"; 
1892  305 

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prove "de_Morgan_disj" "(~(P  Q)) = (~P & ~Q)"; 
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prove "de_Morgan_conj" "(~(P & Q)) = (~P  ~Q)"; 
1922  308 
prove "not_iff" "(P~=Q) = (P = (~Q))"; 
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1660  310 
prove "not_all" "(~ (! x.P(x))) = (? x.~P(x))"; 
1922  311 
prove "imp_all" "((! x. P x) > Q) = (? x. P x > Q)"; 
1660  312 
prove "not_ex" "(~ (? x.P(x))) = (! x.~P(x))"; 
1922  313 
prove "imp_ex" "((? x. P x) > Q) = (! x. P x > Q)"; 
1660  314 

1655  315 
prove "ex_disj_distrib" "(? x. P(x)  Q(x)) = ((? x. P(x))  (? x. Q(x)))"; 
316 
prove "all_conj_distrib" "(!x. P(x) & Q(x)) = ((! x. P(x)) & (! x. Q(x)))"; 

317 

1758  318 

1655  319 
qed_goal "if_cancel" HOL.thy "(if c then x else x) = x" 
320 
(fn _ => [simp_tac (HOL_ss setloop (split_tac [expand_if])) 1]); 

321 

322 
qed_goal "if_distrib" HOL.thy 

323 
"f(if c then x else y) = (if c then f x else f y)" 

324 
(fn _ => [simp_tac (HOL_ss setloop (split_tac [expand_if])) 1]); 

325 

1874  326 
qed_goalw "o_assoc" HOL.thy [o_def] "f o (g o h) = (f o g o h)" 
1655  327 
(fn _=>[rtac ext 1, rtac refl 1]); 
1984  328 

329 

330 

331 

332 
(*** Install simpsets and datatypes in theory structure ***) 

333 

334 
simpset := HOL_ss; 

335 

336 
exception SS_DATA of simpset; 

337 

338 
let fun merge [] = SS_DATA empty_ss 

339 
 merge ss = let val ss = map (fn SS_DATA x => x) ss; 

340 
in SS_DATA (foldl merge_ss (hd ss, tl ss)) end; 

341 

342 
fun put (SS_DATA ss) = simpset := ss; 

343 

344 
fun get () = SS_DATA (!simpset); 

345 
in add_thydata "HOL" 

346 
("simpset", ThyMethods {merge = merge, put = put, get = get}) 

347 
end; 

348 

349 
type dtype_info = {case_const:term, case_rewrites:thm list, 

350 
constructors:term list, nchotomy:thm, case_cong:thm}; 

351 

352 
exception DT_DATA of (string * dtype_info) list; 

353 
val datatypes = ref [] : (string * dtype_info) list ref; 

354 

355 
let fun merge [] = DT_DATA [] 

356 
 merge ds = 

357 
let val ds = map (fn DT_DATA x => x) ds; 

358 
in DT_DATA (foldl (gen_union eq_fst) (hd ds, tl ds)) end; 

359 

360 
fun put (DT_DATA ds) = datatypes := ds; 

361 

362 
fun get () = DT_DATA (!datatypes); 

363 
in add_thydata "HOL" 

364 
("datatypes", ThyMethods {merge = merge, put = put, get = get}) 

365 
end; 

366 

367 

368 
add_thy_reader_file "thy_data.ML"; 