Specificity (WD, CT) For our weighted decoding models, the extreme settings (very generic and very specific) score poorly in engagingness due to the frequent presence of degenerate output -see Figure 3 (middle).
to fix this, we introduce an extra setting z = 10 (boost), in which we do not use the feature extrep bigram for weighted decoding during beam search, but we do use it to rerank the candidates after beam search.