static CLAUSE inf_CreateURUnitResolvent(CLAUSE Clause, int i, SUBST Subst,
LIST FoundMap, FLAGSTORE Flags,
PRECEDENCE Precedence)
/**************************************************************
INPUT: A non-unit clause, a literal index from the clause,
a substitution, a list of pairs (l1, l2) of literals,
where l1 is from the non-unit clause and l2 is from a
unit clause, a flag store and a precedence.
RETURNS: The resolvent of this UR resolution inference. The
clause consists of the literal at index <i> in <Clause>
after application of <Subst>.
EFFECT: The flag store and the precedence are needed to create
the new clause.
***************************************************************/
{
CLAUSE Result, PClause;
LITERAL Lit;
TERM Atom;
LIST Parents;
NAT depth;
/* Create atom for resolvent */
Atom = subst_Apply(Subst, term_Copy(clause_GetLiteralAtom(Clause, i)));
/* Create clause */
Parents = list_List(Atom);
if (i <= clause_LastConstraintLitIndex(Clause))
Result = clause_Create(Parents, list_Nil(), list_Nil(), Flags, Precedence);
else if (i <= clause_LastAntecedentLitIndex(Clause))
Result = clause_Create(list_Nil(), Parents, list_Nil(), Flags, Precedence);
else
Result = clause_Create(list_Nil(), list_Nil(), Parents, Flags, Precedence);
list_Delete(Parents);
/* Get parent clauses and literals, calculate depth of resolvent */
Parents = list_List(Clause);
depth = clause_Depth(Clause);
for ( ; !list_Empty(FoundMap); FoundMap = list_Cdr(FoundMap)) {
Lit = list_PairSecond(list_Car(FoundMap)); /* Literal from unit */
PClause = clause_LiteralOwningClause(Lit);
Parents = list_Cons(PClause, Parents);
depth = misc_Max(depth, clause_Depth(PClause));
clause_AddParentClause(Result, clause_Number(PClause));
clause_AddParentLiteral(Result, clause_LiteralGetIndex(Lit));
Lit = list_PairFirst(list_Car(FoundMap)); /* Is from <Clause> */
clause_AddParentClause(Result, clause_Number(Clause));
clause_AddParentLiteral(Result, clause_LiteralGetIndex(Lit));
}
clause_SetFromURResolution(Result);
clause_SetDepth(Result, depth+1);
clause_SetSplitDataFromList(Result, Parents);
list_Delete(Parents);
return Result;
}
static CLAUSE red_CreateTerminatorEmptyClause(LIST FoundMap, FLAGSTORE Flags,
PRECEDENCE Precedence)
/**************************************************************
INPUT: A list of pairs (l1, l2), where l1 and l2 are unifiable
literals with complementary sign and a flag store.
More accurately, a substitution s exists,
such that l1 s = l2 s for all pairs (l1,l2) in
<FoundMap>.
For all literals l from the involved clauses
there exists one pair (l1,l2) in <FoundMap>
with l1=l or l2=l.
The flags store and the precedence are needed to create
the new clause.
RETURNS: A newly created empty clause, where the data
(parents,...) is set according to <FoundMap>.
***************************************************************/
{
CLAUSE Result, PClause;
LITERAL Lit;
LIST Parents;
NAT depth;
Result = clause_Create(list_Nil(), list_Nil(), list_Nil(), Flags, Precedence);
Parents = list_Nil();
depth = 0;
for (; !list_Empty(FoundMap); FoundMap = list_Cdr(FoundMap)) {
Lit = list_PairSecond(list_Car(FoundMap));
PClause = clause_LiteralOwningClause(Lit);
Parents = list_Cons(PClause, Parents);
depth = misc_Max(depth, clause_Depth(PClause));
clause_AddParentClause(Result, clause_Number(PClause));
clause_AddParentLiteral(Result, clause_LiteralGetIndex(Lit));
Lit = list_PairFirst(list_Car(FoundMap));
PClause = clause_LiteralOwningClause(Lit);
Parents = list_Cons(PClause, Parents);
depth = misc_Max(depth, clause_Depth(PClause));
clause_AddParentClause(Result, clause_Number(PClause));
clause_AddParentLiteral(Result, clause_LiteralGetIndex(Lit));
}
clause_SetFromTerminator(Result);
clause_SetDepth(Result, depth+1);
clause_SetSplitDataFromList(Result, Parents);
list_Delete(Parents);
return Result;
}
LIST split_Backtrack(PROOFSEARCH PS, CLAUSE EmptyClause, CLAUSE* SplitClause)
/**************************************************************
INPUT: A proofsearch object, an empty clause and a pointer to a clause
used as return value.
RETURNS: A list of clauses deleted in the backtracked split levels.
<*SplitClause> is set to the split clause for the right branch
of the splitting step, or NULL, if the tableau is finished.
EFFECT: Backtracks the top of the split stack wrt the empty clause's level
***************************************************************/
{
SPLIT ActBacktrackSplit;
LIST RecoverList, Scan;
int Backtracklevel;
ActBacktrackSplit = (SPLIT)NULL;
RecoverList = split_RemoveUnnecessarySplits(PS, EmptyClause);
Backtracklevel = clause_SplitLevel(EmptyClause);
*SplitClause = NULL;
/* Backtrack all split levels bigger than the level of the empty clause */
while (!prfs_SplitStackEmpty(PS) && (prfs_ValidLevel(PS) > Backtracklevel)) {
ActBacktrackSplit = prfs_SplitStackTop(PS);
prfs_SplitStackPop(PS);
if (prfs_SplitFatherClause(ActBacktrackSplit) != (CLAUSE)NULL) {
RecoverList = list_Cons(prfs_SplitFatherClause(ActBacktrackSplit),
RecoverList);
prfs_SplitSetFatherClause(ActBacktrackSplit, NULL);
}
RecoverList = list_Nconc(prfs_SplitDeletedClauses(ActBacktrackSplit),
RecoverList);
clause_DeleteClauseList(prfs_SplitBlockedClauses(ActBacktrackSplit));
prfs_SplitFree(ActBacktrackSplit);
prfs_DecValidLevel(PS);
}
/* Backtrack further for all right branches on top of the stack */
while (!prfs_SplitStackEmpty(PS) &&
list_Empty(prfs_SplitBlockedClauses(prfs_SplitStackTop(PS)))) {
ActBacktrackSplit = prfs_SplitStackTop(PS);
prfs_SplitStackPop(PS);
if (prfs_SplitFatherClause(ActBacktrackSplit) != (CLAUSE)NULL)
RecoverList = list_Cons(prfs_SplitFatherClause(ActBacktrackSplit),
RecoverList);
RecoverList = list_Nconc(prfs_SplitDeletedClauses(ActBacktrackSplit),
RecoverList);
prfs_SplitFree(ActBacktrackSplit);
prfs_DecValidLevel(PS);
}
if (!prfs_SplitStackEmpty(PS)) {
/* Enter the right branch of the splitting step */
int SplitMinus1;
LIST RightClauses;
SplitMinus1 = prfs_ValidLevel(PS) - 1;
ActBacktrackSplit = prfs_SplitStackTop(PS);
RecoverList = list_Nconc(prfs_SplitDeletedClauses(ActBacktrackSplit),
RecoverList);
prfs_SplitSetDeletedClauses(ActBacktrackSplit, list_Nil());
RecoverList = split_DeleteInvalidClausesFromList(PS, SplitMinus1,
RecoverList);
RightClauses = prfs_SplitBlockedClauses(ActBacktrackSplit);
prfs_SplitSetBlockedClauses(ActBacktrackSplit, list_Nil());
for (Scan = RightClauses; !list_Empty(Scan); Scan = list_Cdr(Scan)) {
if (clause_Number(list_Car(Scan)) == 0) {
/* Found the right clause, the negation clauses have number -1. */
#ifdef CHECK
if (*SplitClause != NULL) {
misc_StartErrorReport();
misc_ErrorReport("\n In split_Backtrack:");
misc_ErrorReport(" Found two blocked clauses ");
misc_ErrorReport("\n with clause number 0 (this marks the clause ");
misc_ErrorReport("\n for the right branch of the tableau).");
misc_FinishErrorReport();
}
#endif
*SplitClause = list_Car(Scan);
}
clause_NewNumber((CLAUSE) list_Car(Scan));
clause_AddParentClause((CLAUSE) list_Car(Scan), clause_Number(EmptyClause));
clause_AddParentLiteral((CLAUSE) list_Car(Scan), 0); /* dummy literal */
}
#ifdef CHECK
if (*SplitClause == NULL) {
misc_StartErrorReport();
misc_ErrorReport("\n In split_Backtrack: Didn´t find a blocked clause");
misc_ErrorReport("\n with clause number 0. (this marks the clause ");
misc_ErrorReport("\n for the right branch of the tableau).");
misc_FinishErrorReport();
}
#endif
RecoverList = list_Nconc(RightClauses, RecoverList);
/* Then, delete clauses from current level (Hack) */
prfs_DecValidLevel(PS);
prfs_MoveInvalidClausesDocProof(PS);
split_DeleteInvalidClausesFromStack(PS);
prfs_IncValidLevel(PS);
} else {
/* Don't delete clauses from current level (split is top level) */
prfs_MoveInvalidClausesDocProof(PS);
for (Scan = RecoverList; !list_Empty(Scan); Scan = list_Cdr(Scan))
prfs_InsertDocProofClause(PS, list_Car(Scan));
list_Delete(RecoverList);
RecoverList = list_Nil();
}
prfs_SetLastBacktrackLevel(PS, prfs_ValidLevel(PS));
return RecoverList;
}