src/HOL/simpdata.ML
 author wenzelm Fri, 13 Mar 1998 18:15:14 +0100 changeset 4744 4469d498cd48 parent 4743 b3bfcbd9fb93 child 4769 bb60149fe21b permissions -rw-r--r--
moved addsplits [expand_if] from HOL_basic_ss to HOL_ss;
```
(*  Title:      HOL/simpdata.ML
ID:         \$Id\$
Author:     Tobias Nipkow
Copyright   1991  University of Cambridge

Instantiation of the generic simplifier
*)

section "Simplifier";

open Simplifier;

(*** Addition of rules to simpsets and clasets simultaneously ***)

(*Takes UNCONDITIONAL theorems of the form A<->B to
the Safe Intr     rule B==>A and
the Safe Destruct rule A==>B.
Also ~A goes to the Safe Elim rule A ==> ?R
Failing other cases, A is added as a Safe Intr rule*)
local
val iff_const = HOLogic.eq_const HOLogic.boolT;

fun addIff th =
(case HOLogic.dest_Trueprop (#prop(rep_thm th)) of
(Const("Not",_) \$ A) =>
AddSEs [zero_var_indexes (th RS notE)]
| (con \$ _ \$ _) =>
if con=iff_const
then (AddSIs [zero_var_indexes (th RS iffD2)];
AddSDs [zero_var_indexes (th RS iffD1)])
else  AddSIs [th]
| _ => AddSIs [th];
Addsimps [th])
handle _ => error ("AddIffs: theorem must be unconditional\n" ^
string_of_thm th)

fun delIff th =
(case HOLogic.dest_Trueprop (#prop(rep_thm th)) of
(Const("Not",_) \$ A) =>
Delrules [zero_var_indexes (th RS notE)]
| (con \$ _ \$ _) =>
if con=iff_const
then Delrules [zero_var_indexes (th RS iffD2),
make_elim (zero_var_indexes (th RS iffD1))]
else Delrules [th]
| _ => Delrules [th];
Delsimps [th])
handle _ => warning("DelIffs: ignoring conditional theorem\n" ^
string_of_thm th)
in
val AddIffs = seq addIff
val DelIffs = seq delIff
end;

qed_goal "meta_eq_to_obj_eq" HOL.thy "x==y ==> x=y"
(fn [prem] => [rewtac prem, rtac refl 1]);

local

fun prover s = prove_goal HOL.thy s (K [blast_tac HOL_cs 1]);

val P_imp_P_iff_True = prover "P --> (P = True)" RS mp;
val P_imp_P_eq_True = P_imp_P_iff_True RS eq_reflection;

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

fun atomize pairs =
let fun atoms th =
(case concl_of th of
Const("Trueprop",_) \$ p =>
(case head_of p of
Const(a,_) =>
(case assoc(pairs,a) of
Some(rls) => flat (map atoms ([th] RL rls))
| None => [th])
| _ => [th])
| _ => [th])
in atoms end;

fun gen_all th = forall_elim_vars (#maxidx(rep_thm th)+1) th;

in

fun mk_meta_eq r = r RS eq_reflection;
fun mk_meta_eq_True r = Some(r RS meta_eq_to_obj_eq RS P_imp_P_eq_True);

fun mk_meta_eq_simp r = case concl_of r of
Const("==",_)\$_\$_ => r
|   _\$(Const("op =",_)\$lhs\$rhs) => mk_meta_eq r
|   _\$(Const("Not",_)\$_) => r RS not_P_imp_P_eq_False
|   _ => r RS P_imp_P_eq_True;
(* last 2 lines requires all formulae to be of the from Trueprop(.) *)

val simp_thms = map prover
[ "(x=x) = True",
"(~True) = False", "(~False) = True", "(~ ~ P) = P",
"(~P) ~= P", "P ~= (~P)", "(P ~= Q) = (P = (~Q))",
"(True=P) = P", "(P=True) = P", "(False=P) = (~P)", "(P=False) = (~P)",
"(True --> P) = P", "(False --> P) = True",
"(P --> True) = True", "(P --> P) = True",
"(P --> False) = (~P)", "(P --> ~P) = (~P)",
"(P & True) = P", "(True & P) = P",
"(P & False) = False", "(False & P) = False",
"(P & P) = P", "(P & (P & Q)) = (P & Q)",
"(P & ~P) = False",    "(~P & P) = False",
"(P | True) = True", "(True | P) = True",
"(P | False) = P", "(False | P) = P",
"(P | P) = P", "(P | (P | Q)) = (P | Q)",
"(P | ~P) = True",    "(~P | P) = True",
"((~P) = (~Q)) = (P=Q)",
"(!x. P) = P", "(? x. P) = P", "? x. x=t", "? x. t=x",
(*two needed for the one-point-rule quantifier simplification procs*)
"(? x. x=t & P(x)) = P(t)",		(*essential for termination!!*)
"(! x. t=x --> P(x)) = P(t)" ];      (*covers a stray case*)

(*Add congruence rules for = (instead of ==) *)
infix 4 addcongs delcongs;

fun mk_meta_cong rl =
standard(mk_meta_eq(replicate (nprems_of rl) meta_eq_to_obj_eq MRS rl))
handle THM _ =>
error("Premises and conclusion of congruence rules must be =-equalities");

fun ss addcongs congs = ss addeqcongs (map mk_meta_cong congs);

fun ss delcongs congs = ss deleqcongs (map mk_meta_cong congs);

fun Addcongs congs = (simpset_ref() := simpset() addcongs congs);
fun Delcongs congs = (simpset_ref() := simpset() delcongs congs);

fun mksimps pairs = map mk_meta_eq_simp o atomize pairs o gen_all;

val imp_cong = impI RSN
(2, prove_goal HOL.thy "(P=P')--> (P'--> (Q=Q'))--> ((P-->Q) = (P'-->Q'))"
(fn _=> [blast_tac HOL_cs 1]) RS mp RS mp);

(*Miniscoping: pushing in existential quantifiers*)
val ex_simps = map prover
["(EX x. P x & Q)   = ((EX x. P x) & Q)",
"(EX x. P & Q x)   = (P & (EX x. Q x))",
"(EX x. P x | Q)   = ((EX x. P x) | Q)",
"(EX x. P | Q x)   = (P | (EX x. Q x))",
"(EX x. P x --> Q) = ((ALL x. P x) --> Q)",
"(EX x. P --> Q x) = (P --> (EX x. Q x))"];

(*Miniscoping: pushing in universal quantifiers*)
val all_simps = map prover
["(ALL x. P x & Q)   = ((ALL x. P x) & Q)",
"(ALL x. P & Q x)   = (P & (ALL x. Q x))",
"(ALL x. P x | Q)   = ((ALL x. P x) | Q)",
"(ALL x. P | Q x)   = (P | (ALL x. Q x))",
"(ALL x. P x --> Q) = ((EX x. P x) --> Q)",
"(ALL x. P --> Q x) = (P --> (ALL x. Q x))"];

(* elimination of existential quantifiers in assumptions *)

val ex_all_equiv =
let val lemma1 = prove_goal HOL.thy
"(? x. P(x) ==> PROP Q) ==> (!!x. P(x) ==> PROP Q)"
(fn prems => [resolve_tac prems 1, etac exI 1]);
val lemma2 = prove_goalw HOL.thy [Ex_def]
"(!!x. P(x) ==> PROP Q) ==> (? x. P(x) ==> PROP Q)"
(fn prems => [REPEAT(resolve_tac prems 1)])
in equal_intr lemma1 lemma2 end;

end;

(* Elimination of True from asumptions: *)

val True_implies_equals = prove_goal HOL.thy
"(True ==> PROP P) == PROP P"
(K [rtac equal_intr_rule 1, atac 2,
METAHYPS (fn prems => resolve_tac prems 1) 1,
rtac TrueI 1]);

fun prove nm thm  = qed_goal nm HOL.thy thm (K [blast_tac HOL_cs 1]);

prove "conj_commute" "(P&Q) = (Q&P)";
prove "conj_left_commute" "(P&(Q&R)) = (Q&(P&R))";
val conj_comms = [conj_commute, conj_left_commute];
prove "conj_assoc" "((P&Q)&R) = (P&(Q&R))";

prove "disj_commute" "(P|Q) = (Q|P)";
prove "disj_left_commute" "(P|(Q|R)) = (Q|(P|R))";
val disj_comms = [disj_commute, disj_left_commute];
prove "disj_assoc" "((P|Q)|R) = (P|(Q|R))";

prove "conj_disj_distribL" "(P&(Q|R)) = (P&Q | P&R)";
prove "conj_disj_distribR" "((P|Q)&R) = (P&R | Q&R)";

prove "disj_conj_distribL" "(P|(Q&R)) = ((P|Q) & (P|R))";
prove "disj_conj_distribR" "((P&Q)|R) = ((P|R) & (Q|R))";

prove "imp_conjR" "(P --> (Q&R)) = ((P-->Q) & (P-->R))";
prove "imp_conjL" "((P&Q) -->R)  = (P --> (Q --> R))";
prove "imp_disjL" "((P|Q) --> R) = ((P-->R)&(Q-->R))";

(*These two are specialized, but imp_disj_not1 is useful in Auth/Yahalom.ML*)
prove "imp_disj_not1" "((P --> Q | R)) = (~Q --> P --> R)";
prove "imp_disj_not2" "((P --> Q | R)) = (~R --> P --> Q)";

prove "imp_disj1" "((P-->Q)|R) = (P--> Q|R)";
prove "imp_disj2" "(Q|(P-->R)) = (P--> Q|R)";

prove "de_Morgan_disj" "(~(P | Q)) = (~P & ~Q)";
prove "de_Morgan_conj" "(~(P & Q)) = (~P | ~Q)";
prove "not_imp" "(~(P --> Q)) = (P & ~Q)";
prove "not_iff" "(P~=Q) = (P = (~Q))";
prove "disj_not1" "(~P | Q) = (P --> Q)";
prove "disj_not2" "(P | ~Q) = (Q --> P)"; (* changes orientation :-( *)

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

prove "not_all" "(~ (! x. P(x))) = (? x.~P(x))";
prove "imp_all" "((! x. P x) --> Q) = (? x. P x --> Q)";
prove "not_ex"  "(~ (? x. P(x))) = (! x.~P(x))";
prove "imp_ex" "((? x. P x) --> Q) = (! x. P x --> Q)";

prove "ex_disj_distrib" "(? x. P(x) | Q(x)) = ((? x. P(x)) | (? x. Q(x)))";
prove "all_conj_distrib" "(!x. P(x) & Q(x)) = ((! x. P(x)) & (! x. Q(x)))";

(* '&' congruence rule: not included by default!
May slow rewrite proofs down by as much as 50% *)

let val th = prove_goal HOL.thy
"(P=P')--> (P'--> (Q=Q'))--> ((P&Q) = (P'&Q'))"
(fn _=> [blast_tac HOL_cs 1])
in  bind_thm("conj_cong",standard (impI RSN (2, th RS mp RS mp)))  end;

let val th = prove_goal HOL.thy
"(Q=Q')--> (Q'--> (P=P'))--> ((P&Q) = (P'&Q'))"
(fn _=> [blast_tac HOL_cs 1])
in  bind_thm("rev_conj_cong",standard (impI RSN (2, th RS mp RS mp)))  end;

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

let val th = prove_goal HOL.thy
"(P=P')--> (~P'--> (Q=Q'))--> ((P|Q) = (P'|Q'))"
(fn _=> [blast_tac HOL_cs 1])
in  bind_thm("disj_cong",standard (impI RSN (2, th RS mp RS mp)))  end;

prove "eq_sym_conv" "(x=y) = (y=x)";

qed_goalw "o_apply" HOL.thy [o_def] "(f o g) x = f (g x)"
(K [rtac refl 1]);

qed_goalw "if_True" HOL.thy [if_def] "(if True then x else y) = x"
(K [Blast_tac 1]);

qed_goalw "if_False" HOL.thy [if_def] "(if False then x else y) = y"
(K [Blast_tac 1]);

qed_goal "if_P" HOL.thy "P ==> (if P then x else y) = x"
(fn [prem] => [ stac (prem RS eqTrueI) 1, rtac if_True 1 ]);
(*
qed_goal "if_not_P" HOL.thy "~P ==> (if P then x else y) = y"
(fn [prem] => [ stac (prem RS not_P_imp_P_iff_F) 1, rtac if_False 1 ]);
*)
qed_goalw "if_not_P" HOL.thy [if_def] "!!P. ~P ==> (if P then x else y) = y"
(K [Blast_tac 1]);

qed_goal "expand_if" HOL.thy
"P(if Q then x else y) = ((Q --> P(x)) & (~Q --> P(y)))" (K [
res_inst_tac [("Q","Q")] (excluded_middle RS disjE) 1,
stac if_P 2,
stac if_not_P 1,
ALLGOALS (blast_tac HOL_cs)]);

qed_goal "split_if_asm" HOL.thy
"P(if Q then x else y) = (~((Q & ~P x) | (~Q & ~P y)))" (K [
stac expand_if 1,
blast_tac HOL_cs 1]);

qed_goal "if_bool_eq" HOL.thy
"(if P then Q else R) = ((P-->Q) & (~P-->R))"
(K [rtac expand_if 1]);

(*** make simplification procedures for quantifier elimination ***)

structure Quantifier1 = Quantifier1Fun(
struct
(*abstract syntax*)
fun dest_eq((c as Const("op =",_)) \$ s \$ t) = Some(c,s,t)
| dest_eq _ = None;
fun dest_conj((c as Const("op &",_)) \$ s \$ t) = Some(c,s,t)
| dest_conj _ = None;
val conj = HOLogic.conj
val imp  = HOLogic.imp
(*rules*)
val iff_reflection = eq_reflection
val iffI = iffI
val sym  = sym
val conjI= conjI
val conjE= conjE
val impI = impI
val impE = impE
val mp   = mp
val exI  = exI
val exE  = exE
val allI = allI
val allE = allE
end);

local
val ex_pattern =
read_cterm (sign_of HOL.thy) ("EX x. P(x) & Q(x)",HOLogic.boolT)

val all_pattern =
read_cterm (sign_of HOL.thy) ("ALL x. P(x) & P'(x) --> Q(x)",HOLogic.boolT)

in
val defEX_regroup =
mk_simproc "defined EX" [ex_pattern] Quantifier1.rearrange_ex;
val defALL_regroup =
mk_simproc "defined ALL" [all_pattern] Quantifier1.rearrange_all;
end;

(*** Case splitting ***)

local val mktac = mk_case_split_tac (meta_eq_to_obj_eq RS iffD2)
in
fun split_tac splits = mktac (map mk_meta_eq splits)
end;

local val mktac = mk_case_split_inside_tac (meta_eq_to_obj_eq RS iffD2)
in
fun split_inside_tac splits = mktac (map mk_meta_eq splits)
end;

val split_asm_tac = mk_case_split_asm_tac split_tac
(disjE,conjE,exE,contrapos,contrapos2,notnotD);

infix 4 addsplits delsplits;

fun ss addsplits splits =
let fun addsplit(ss,split) =
let val name = "split " ^ const_of_split_thm split
in ss addloop (name,split_tac [split]) end
in foldl addsplit (ss,splits) end;

fun ss delsplits splits =
let fun delsplit(ss,split) =
let val name = "split " ^ const_of_split_thm split
in ss delloop name end
in foldl delsplit (ss,splits) end;

fun Addsplits splits = (simpset_ref() := simpset() addsplits splits);
fun Delsplits splits = (simpset_ref() := simpset() delsplits splits);

qed_goal "if_cancel" HOL.thy "(if c then x else x) = x"
(K [split_tac [expand_if] 1, blast_tac HOL_cs 1]);

qed_goal "if_eq_cancel" HOL.thy "(if x = y then y else x) = x"
(K [split_tac [expand_if] 1, blast_tac HOL_cs 1]);

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

(*Simplifies x assuming c and y assuming ~c*)
qed_goal "if_cong" HOL.thy
"[| b=c; c ==> x=u; ~c ==> y=v |] ==>\
\  (if b then x else y) = (if c then u else v)"
(fn rew::prems =>
[stac rew 1, stac expand_if 1, stac expand_if 1,
blast_tac (HOL_cs addDs prems) 1]);

(*Prevents simplification of x and y: much faster*)
qed_goal "if_weak_cong" HOL.thy
"b=c ==> (if b then x else y) = (if c then x else y)"
(fn [prem] => [rtac (prem RS arg_cong) 1]);

(*Prevents simplification of t: much faster*)
qed_goal "let_weak_cong" HOL.thy
"a = b ==> (let x=a in t(x)) = (let x=b in t(x))"
(fn [prem] => [rtac (prem RS arg_cong) 1]);

(*In general it seems wrong to add distributive laws by default: they
might cause exponential blow-up.  But imp_disjL has been in for a while
and cannot be removed without affecting existing proofs.  Moreover,
rewriting by "(P|Q --> R) = ((P-->R)&(Q-->R))" might be justified on the
grounds that it allows simplification of R in the two cases.*)

val mksimps_pairs =
[("op -->", [mp]), ("op &", [conjunct1,conjunct2]),
("All", [spec]), ("True", []), ("False", []),
("If", [if_bool_eq RS iffD1])];

fun unsafe_solver prems = FIRST'[resolve_tac (reflexive_thm::TrueI::refl::prems),
atac, etac FalseE];
(*No premature instantiation of variables during simplification*)
fun   safe_solver prems = FIRST'[match_tac (reflexive_thm::TrueI::prems),
eq_assume_tac, ematch_tac [FalseE]];

val HOL_basic_ss = empty_ss setsubgoaler asm_simp_tac
setSSolver   safe_solver
setSolver  unsafe_solver
setmksimps (mksimps mksimps_pairs)
setmkeqTrue mk_meta_eq_True;

val HOL_ss =
HOL_basic_ss addsimps
([triv_forall_equality, (* prunes params *)
True_implies_equals, (* prune asms `True' *)
if_True, if_False, if_cancel, if_eq_cancel,
o_apply, imp_disjL, conj_assoc, disj_assoc,
de_Morgan_conj, de_Morgan_disj, imp_disj1, imp_disj2, not_imp,
disj_not1, not_all, not_ex, cases_simp]
@ ex_simps @ all_simps @ simp_thms)
addsimprocs [defALL_regroup,defEX_regroup]
addcongs [imp_cong]
addsplits [expand_if];

qed_goal "if_distrib" HOL.thy
"f(if c then x else y) = (if c then f x else f y)"
(K [simp_tac (HOL_ss setloop (split_tac [expand_if])) 1]);

qed_goalw "o_assoc" HOL.thy [o_def] "f o (g o h) = f o g o h"
(K [rtac ext 1, rtac refl 1]);

(*For expand_case_tac*)
val prems = goal HOL.thy "[| P ==> Q(True); ~P ==> Q(False) |] ==> Q(P)";
by (case_tac "P" 1);
by (ALLGOALS (asm_simp_tac (HOL_ss addsimps prems)));
val expand_case = result();

(*Used in Auth proofs.  Typically P contains Vars that become instantiated
during unification.*)
fun expand_case_tac P i =
res_inst_tac [("P",P)] expand_case i THEN
Simp_tac (i+1) THEN
Simp_tac i;

(* install implicit simpset *)

simpset_ref() := HOL_ss;

(*** Integration of simplifier with classical reasoner ***)

(* rot_eq_tac rotates the first equality premise of subgoal i to the front,
fails if there is no equaliy or if an equality is already at the front *)
local
fun is_eq (Const ("Trueprop", _) \$ (Const("op ="  ,_) \$ _ \$ _)) = true
| is_eq _ = false;
val find_eq = find_index is_eq;
in
val rot_eq_tac =
SUBGOAL (fn (Bi,i) => let val n = find_eq (Logic.strip_assums_hyp Bi) in
if n>0 then rotate_tac n i else no_tac end)
end;

use "\$ISABELLE_HOME/src/Provers/clasimp.ML";
open Clasimp;

val HOL_css = (HOL_cs, HOL_ss);
```