package aima.core.probability.proposition;
import java.util.Iterator;
import java.util.Map;
import aima.core.probability.RandomVariable;
public class EquivalentProposition extends AbstractDerivedProposition {
//
private String toString = null;
public EquivalentProposition(String name, RandomVariable... equivs) {
super(name);
if (null == equivs || 1 >= equivs.length) {
throw new IllegalArgumentException(
"Equivalent variables must be specified.");
}
for (RandomVariable rv : equivs) {
addScope(rv);
}
}
//
// START-Proposition
public boolean holds(Map<RandomVariable, Object> possibleWorld) {
boolean holds = true;
Iterator<RandomVariable> i = getScope().iterator();
RandomVariable rvC, rvL = i.next();
while (i.hasNext()) {
rvC = i.next();
if (!possibleWorld.get(rvL).equals(possibleWorld.get(rvC))) {
holds = false;
break;
}
rvL = rvC;
}
return holds;
}
// END-Proposition
//
@Override
public String toString() {
if (null == toString) {
StringBuilder sb = new StringBuilder();
sb.append(getDerivedName());
for (RandomVariable rv : getScope()) {
sb.append(" = ");
sb.append(rv);
}
toString = sb.toString();
}
return toString;
}
}