--- a/src/FOLP/int-prover.ML Sat Apr 05 16:00:00 2003 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,79 +0,0 @@
-(* Title: FOL/int-prover
- ID: $Id$
- Author: Lawrence C Paulson, Cambridge University Computer Laboratory
- Copyright 1992 University of Cambridge
-
-A naive prover for intuitionistic logic
-
-BEWARE OF NAME CLASHES WITH CLASSICAL TACTICS -- use Int.fast_tac ...
-
-Completeness (for propositional logic) is proved in
-
-Roy Dyckhoff.
-Contraction-Free Sequent Calculi for Intuitionistic Logic.
-J. Symbolic Logic (in press)
-*)
-
-signature INT_PROVER =
- sig
- val best_tac: int -> tactic
- val fast_tac: int -> tactic
- val inst_step_tac: int -> tactic
- val safe_step_tac: int -> tactic
- val safe_brls: (bool * thm) list
- val safe_tac: tactic
- val step_tac: int -> tactic
- val haz_brls: (bool * thm) list
- end;
-
-
-structure Int : INT_PROVER =
-struct
-
-(*Negation is treated as a primitive symbol, with rules notI (introduction),
- not_to_imp (converts the assumption ~P to P-->False), and not_impE
- (handles double negations). Could instead rewrite by not_def as the first
- step of an intuitionistic proof.
-*)
-val safe_brls = sort lessb
- [ (true,FalseE), (false,TrueI), (false,refl),
- (false,impI), (false,notI), (false,allI),
- (true,conjE), (true,exE),
- (false,conjI), (true,conj_impE),
- (true,disj_impE), (true,ex_impE),
- (true,disjE), (false,iffI), (true,iffE), (true,not_to_imp) ];
-
-val haz_brls =
- [ (false,disjI1), (false,disjI2), (false,exI),
- (true,allE), (true,not_impE), (true,imp_impE), (true,iff_impE),
- (true,all_impE), (true,impE) ];
-
-(*0 subgoals vs 1 or more: the p in safep is for positive*)
-val (safe0_brls, safep_brls) =
- partition (apl(0,op=) o subgoals_of_brl) safe_brls;
-
-(*Attack subgoals using safe inferences*)
-val safe_step_tac = FIRST' [uniq_assume_tac,
- IFOLP_Lemmas.uniq_mp_tac,
- biresolve_tac safe0_brls,
- hyp_subst_tac,
- biresolve_tac safep_brls] ;
-
-(*Repeatedly attack subgoals using safe inferences*)
-val safe_tac = DETERM (REPEAT_FIRST safe_step_tac);
-
-(*These steps could instantiate variables and are therefore unsafe.*)
-val inst_step_tac = assume_tac APPEND' mp_tac;
-
-(*One safe or unsafe step. *)
-fun step_tac i = FIRST [safe_tac, inst_step_tac i, biresolve_tac haz_brls i];
-
-(*Dumb but fast*)
-val fast_tac = SELECT_GOAL (DEPTH_SOLVE (step_tac 1));
-
-(*Slower but smarter than fast_tac*)
-val best_tac =
- SELECT_GOAL (BEST_FIRST (has_fewer_prems 1, size_of_thm) (step_tac 1));
-
-end;
-