UnifyWithOccursCheck

java.lang.Object
- org.projog.core.predicate.AbstractSingleResultPredicate
- - org.projog.core.predicate.builtin.compare.UnifyWithOccursCheck

All Implemented Interfaces:

KnowledgeBaseConsumer, PredicateFactory
```
public final class UnifyWithOccursCheck
extends AbstractSingleResultPredicate
```
unify_with_occurs_check(X, Y) - an equality test using sound unification.
Works like X = Y but with an additional check to avoid cyclic terms. When using unify_with_occurs_check a variable can only be unified with a term if that term does not contain the variable.

Constructor Summary

Constructors
Constructor Description

UnifyWithOccursCheck()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected boolean`	`evaluate(Term arg1, Term arg2)`
`private boolean`	`isCyclic(Term t)`
`private boolean`	`isCyclic(Term t, java.util.Set<Term> parents)`

Methods inherited from class org.projog.core.predicate.AbstractSingleResultPredicate
evaluate, evaluate, evaluate, evaluate, evaluate, getArithmeticOperators, getFileHandles, getKnowledgeBase, getOperands, getPredicate, getPredicates, getProjogListeners, getSpyPoints, getTermFormatter, init, isRetryable, setKnowledgeBase

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.projog.core.predicate.PredicateFactory
isAlwaysCutOnBacktrack

Constructor Detail
- UnifyWithOccursCheck
```
public UnifyWithOccursCheck()
```

Method Detail

evaluate

protected boolean evaluate(Term arg1,
                           Term arg2)

Overrides:: evaluate in class AbstractSingleResultPredicate

isCyclic
```
private boolean isCyclic(Term t)
```

isCyclic

private boolean isCyclic(Term t,
                         java.util.Set<Term> parents)