arxivcs.LGeess.IVstat.ML2026-07-14
What Does Goodness Measure? A Likelihood-Ratio Account of Forward-Forward Learning
The Forward-Forward (FF) algorithm trains each layer locally, so that a scalar goodness - the sum of squared activations - is high on real inputs and low on contrastive ones, with activations normalized between layers. Both choices are usually treated as heuristics. Under an expl…