gtakata
commented
7 years ago Not sure I understand this:
1) Why would we want to multiply disconnected models together? It would seem that you would want to do the elimination only on the one that has the target. The other should have no distribution over the target anyway. 2) Shouldn't the product method already take care of this? ie shouldn't two factors have variables in common in order to be multiplied? If so, multiplying by an empty factor should be a no-op.
bruttenberg
wkretschmer
apfeffer
At the end of VE, all factors are multiplied together and everything is eliminated but the target. When you have a disconnected model though, you end up with an empty factor that could potentially be zero. When this empty factor is multiplied by the non-empty factors, it can zero out the result. A small fix in VE can fix this:
private def makeResultFactor(factorsAfterElimination: MultiSet[Factor[Double]]): Factor[Double] = { // It is possible that there are no factors (this will happen if there are no queries or evidence). // Therefore, we start with the unit factor and use foldLeft, instead of simply reducing the factorsAfterElimination. val nonEmpty = factorsAfterElimination.filter(p => p.variables.nonEmpty) // This line is new nonEmpty .foldLeft(Factory.unit(semiring))(.product()) }