--- a/src/HOL/Tools/sat_solver.ML Tue Sep 20 18:47:42 2005 +0200
+++ b/src/HOL/Tools/sat_solver.ML Tue Sep 20 19:38:35 2005 +0200
@@ -586,6 +586,7 @@
id::sep::ids =>
let
val _ = if !clause_offset = ~1 then () else raise INVALID_PROOF ("File format error: \"CL:\" disallowed after \"VAR:\".")
+ val _ = if conflict_id = ~1 then () else raise INVALID_PROOF ("File format error: \"CL:\" disallowed after \"CONF:\".")
val cid = int_from_string id
val _ = if sep = "<=" then () else raise INVALID_PROOF ("File format error: \"<=\" expected (" ^ quote sep ^ " encountered).")
val rs = map int_from_string ids
@@ -600,11 +601,12 @@
case toks of
id::levsep::levid::valsep::valid::antesep::anteid::litsep::lits =>
let
+ val _ = if conflict_id = ~1 then () else raise INVALID_PROOF ("File format error: \"VAR:\" disallowed after \"CONF:\".")
(* set 'clause_offset' to the largest used clause ID *)
val _ = if !clause_offset = ~1 then clause_offset :=
(case Inttab.max_key clause_table of
SOME id => id
- | NONE => cnf_number_of_clauses (PropLogic.defcnf fm))
+ | NONE => cnf_number_of_clauses (PropLogic.defcnf fm) - 1 (* the first clause ID is 0, not 1 *))
else
()
val vid = int_from_string id
@@ -629,7 +631,7 @@
in
(* update clause table *)
(Inttab.update_new (cid, rs) clause_table, conflict_id)
- handle Inttab.DUP _ => raise INVALID_PROOF ("File format error: clause " ^ string_of_int cid ^ " (antecedent for variable " ^ id ^ ") defined more than once.")
+ handle Inttab.DUP _ => raise INVALID_PROOF ("File format error: clause " ^ string_of_int cid ^ " (derived from antecedent for variable " ^ id ^ ") already defined.")
end
| _ =>
raise INVALID_PROOF "File format error: \"VAR:\" followed by an insufficient number of tokens."
@@ -637,13 +639,19 @@
case toks of
id::sep::ids =>
let
+ val _ = if conflict_id = ~1 then () else raise INVALID_PROOF "File format error: more than one conflicting clause specified."
val cid = int_from_string id
val _ = if sep = "==" then () else raise INVALID_PROOF ("File format error: \"==\" expected (" ^ quote sep ^ " encountered).")
- val _ = map int_from_string ids
- val _ = if conflict_id = ~1 then () else raise INVALID_PROOF "File format error: more than one conflicting clause specified."
+ val ls = map int_from_string ids
+ (* the conflict clause must be resolved with the unit clauses *)
+ (* for its literals to obtain the empty clause *)
+ val vids = map (fn l => l div 2) ls
+ val rs = cid :: map (fn v => !clause_offset + v) vids
+ val empty_id = getOpt (Inttab.max_key clause_table, ~1) + 1
in
- (* update conflict id *)
- (clause_table, cid)
+ (* update clause table and conflict id *)
+ (Inttab.update_new (empty_id, rs) clause_table, empty_id)
+ handle Inttab.DUP _ => raise INVALID_PROOF ("File format error: clause " ^ string_of_int empty_id ^ " (empty clause derived from clause " ^ id ^ ") already defined.")
end
| _ =>
raise INVALID_PROOF "File format error: \"CONF:\" followed by an insufficient number of tokens."