GrammarRL: Effective Grammar-Constrained Decoding via Reinforcement Learning

Excerpt

arXiv:2609.39869v1 Announce Type: cross Abstract: Grammar-constrained generation guarantees syntactic validity, but can substantially degrade semantic quality when the model's preferred outputs are poorly aligned with the imposed grammar. This trade-off is particularly severe when the prompt is underspecified or the model has limited instruction-following ability. Beam search can partially mitigate these failures by exploring multiple valid sequences, but its computational cost grows with beam w