/**
* compute the feasible region based on the evidence, the method will only use the v2 if 1. v1 is
* a direct parent of v2, or 2. v1 and v2 are the same, i.e. corresponding to evidence variable
*
* @param v1 the variable to sample
* @param v2 the variable corresponding to evidence
* @return
*/
private Region computeRegionFromEvidence(BayesNetVar v1, BayesNetVar v2) {
if (v1.equals(v2)) {
// the variable is in the evidence, it should be directly set to evidence
// value
return new SingletonRegion(evidence.getObservedValue(v2));
}
if (v2 instanceof DerivedVar) {
ArgSpec as = ((DerivedVar) v2).getArgSpec();
if (as instanceof CardinalitySpec) {
// child is cardinality of a set
ImplicitSetSpec iss = ((CardinalitySpec) as).getSetSpec();
Type childType = iss.getType();
if (v1 instanceof NumberVar) {
// parent is number variable, potential match
NumberVar numv1 = (NumberVar) v1;
POP parentPOP = numv1.pop();
Type parentType = parentPOP.type();
if (!parentType.equals(childType)) {
return null;
} else {
// potential match, if
Object[] objs = numv1.args(); // generating objects for parent
// variable
if (objs.length == 0) {
// no any constraint
return Region.FULL_REGION;
} else {
// v1 is parent of v2
Formula cond = iss.getCond();
if (cond.isDetermined(this) && cond.isTrue(this)) {
int value = ((Number) evidence.getObservedValue(v2)).intValue();
// get all previously satisfied var
Set<BayesNetVar> pvars = getAlreadySampledParentVars(v2);
for (BayesNetVar pv : pvars) {
// eliminate the already sampled ones
int a = ((Number) this.getValue(pv)).intValue();
value -= a;
}
// v1 is parent of v2, and will be sampled immediately
pvars.add(v1);
if ((value > 0) && anyMoreNumberVar(childType, cond)) {
return new IntRegion(0, value);
} else {
return new SingletonRegion(value);
}
}
}
}
} /* TODO check other cases of v1 that can be potential parent of this */
} else {
// other cases of argspec in v1
}
} else {
// other variables
// might be parent
// TODO check whether the condition has v1 as parent
}
return null;
}
