コード例 #1
0
ファイル: rules-ur.c プロジェクト: 5432935/crossbridge
static LIST inf_NonUnitURResolution(CLAUSE Clause, int SpecialLitIndex,
				    LIST FoundMap, SUBST Subst,
				    SYMBOL GlobalMaxVar, SHARED_INDEX Index,
				    FLAGSTORE Flags, PRECEDENCE Precedence)
/**************************************************************
  INPUT:   A non-unit clause, a literal index from <Clause>.
           <FoundMap> is a list of pairs (l1,l2) of unifiable literals,
	   where l1 is from <Clause> and l2 is from a unit clause.
	   At this point the list has at most one element.
	   <Subst> is the substitution for <Clause>.
	   <GlobalMaxVar> is the maximal variable encountered so far.
	   <Index> is used to search unifiable literals.
	   The flag store and the precedence are needed to create
	   the new clauses.
  RETURNS: The list of UR resolution resolvents.
  EFFECT:  If inf_URResolution was called with a unit clause,
           <SpecialLitIndex> is the index of a literal from a non-unit
	   clause, that is unifiable with the unit clause's literal,
	   otherwise it is set to -1.
***************************************************************/
{
  LIST Result, RestLits;
  int  i, last;

  Result = list_Nil();
  RestLits = clause_GetLiteralListExcept(Clause, SpecialLitIndex);
  last = clause_LastLitIndex(Clause);
  for (i = clause_FirstLitIndex(); i <= last; i++) {
    /* <i> is the index of the literal that remains in the resolvent */
    if (i != SpecialLitIndex) {
      RestLits = list_PointerDeleteOneElement(RestLits,
					      clause_GetLiteral(Clause,i));
      
      Result = list_Nconc(inf_SearchURResolvents(Clause, i, FoundMap, RestLits,
						 Subst, GlobalMaxVar, Index,
						 Flags, Precedence),
			  Result);
      
      RestLits = list_Cons(clause_GetLiteral(Clause, i), RestLits);
    }
  }
  list_Delete(RestLits);
  return Result;
}
コード例 #2
0
ファイル: terminator.c プロジェクト: Artem-B/test-suite
static CLAUSE red_SearchTerminator(NAT n, LIST RestLits, LIST FoundMap,
				   SUBST Subst, SYMBOL GlobalMaxVar,
				   LIST IndexList, FLAGSTORE Flags,
				   PRECEDENCE Precedence)
/**************************************************************
  INPUT:   A natural number, a list of literals, a list of pairs,
           a substitution, the maximum variable occurring in all
	   involved clauses, a list of SHARED_INDEXes, a flag store
	   and a precedence.
  RETURNS: An empty clause, if a terminator situation was found,
           NULL otherwise.
  EFFECT:  This recursive function implements the search for
           a terminator situation with at most <n> non-unit clauses.
	   <RestLits> is the lists of literals actually missing
	   a complementary partner literal.
	   <FoundMap> is a list of pairs (l1,l2), where l1 and l2
	   are complementary, unifiable literals.
	   <Subst> is the common substitution of all those pairs.
	   <GlobalMaxVar> is the maximum variable from all
	   involved clauses.
	   To enable the search all involved clauses are made
	   variable-disjoint.
	   At the moment the function stops, if ANY terminator
	   situation occurred. This might not be desirable
	   if splitting is enabled, since there might be other
	   terminator situations resulting in an empty clause
	   of lower split level.
	   The flag store and the precedence are needed to create
	   the new clause.
***************************************************************/
{
  if (list_Empty(RestLits)) {
    /* We found a terminator situation, so stop the recursion */
    return red_CreateTerminatorEmptyClause(FoundMap, Flags, Precedence);
  } else {
    CLAUSE  Result, PClauseCopy;
    LITERAL Lit, PLit;
    SYMBOL  NewMaxVar;
    SUBST   NewSubst, RightSubst;
    TERM    AtomCopy;
    LIST    ClashList, ToDoList;
    BOOL    Swapped;
    NAT     Limit;
    int     PLitInd;

    Swapped   = FALSE;
    Result    = clause_Null();
    clause_MoveBestLiteralToFront(RestLits, Subst, GlobalMaxVar,
				  red_TerminatorLitIsBetter);
    Lit       = list_Car(RestLits);
    RestLits  = list_Cdr(RestLits);
    AtomCopy  = subst_Apply(Subst, term_Copy(clause_LiteralAtom(Lit)));

    /* The following 'endless' loop runs twice for equality literals */
    /* and only once for other literals.                             */
    while (TRUE) {
      ClashList = red_GetTerminatorPartnerLits(AtomCopy, Lit, n==0, IndexList);
      for (; !list_Empty(ClashList) && Result==NULL;
	   ClashList = list_Pop(ClashList)) {
	PLit        = list_Car(ClashList);
	PLitInd     = clause_LiteralGetIndex(PLit);
	PClauseCopy = clause_Copy(clause_LiteralOwningClause(PLit));
	Limit       = clause_Length(PClauseCopy) == 1 ? n : n-1;
	
	clause_RenameVarsBiggerThan(PClauseCopy, GlobalMaxVar);
	
	PLit        = clause_GetLiteral(PClauseCopy, PLitInd);
	FoundMap    = list_Cons(list_PairCreate(Lit, PLit), FoundMap);
	ToDoList    = clause_GetLiteralListExcept(PClauseCopy, PLitInd);
	ToDoList    = list_Nconc(ToDoList, list_Copy(RestLits));
	
	NewMaxVar   = clause_SearchMaxVar(PClauseCopy);
	if (symbol_GreaterVariable(GlobalMaxVar, NewMaxVar))
	  NewMaxVar = GlobalMaxVar;
	
	cont_Check();
	if (!unify_UnifyNoOC(cont_LeftContext(), AtomCopy,
			     cont_RightContext(), clause_LiteralAtom(PLit))) {
	  misc_StartErrorReport();
	  misc_ErrorReport("\n In red_SearchTerminator: Unification failed.");
	  misc_FinishErrorReport();
	}
	subst_ExtractUnifier(cont_LeftContext(), &NewSubst,
			     cont_RightContext(), &RightSubst);
	cont_Reset();
	
	/* The domains of both substitutions are disjoint */
	/* so we do just a simple union operation.        */
	NewSubst = subst_NUnion(NewSubst, RightSubst);
	RightSubst = NewSubst;
	NewSubst  = subst_Compose(NewSubst, subst_Copy(Subst));
	subst_Delete(RightSubst);
	
	Result = red_SearchTerminator(Limit, ToDoList, FoundMap, NewSubst,
				      NewMaxVar, IndexList, Flags, Precedence);
	
	clause_Delete(PClauseCopy);
	subst_Delete(NewSubst);
	list_Delete(ToDoList);
	list_PairFree(list_Car(FoundMap));
	FoundMap = list_Pop(FoundMap);
      }
      /* loop control */
      if (!fol_IsEquality(AtomCopy) || Swapped || Result!=NULL)
	break;
      else {
	list_Delete(ClashList);
	term_EqualitySwap(AtomCopy);
	Swapped = TRUE;
      }
    }
    /* cleanup */
    term_Delete(AtomCopy);
    /* <ClashList> may be non-empty since the loop stops */
    /* if a terminator was found.                       */
    list_Delete(ClashList);
    
    return Result;
  }
}