David Alvarez-Melis

@dmelis.bsky.social

Professoring at Harvard || Researching at MSR || Previously: MIT CSAIL, NYU, IBM Research, ITAM

🚨 New preprint! TL;DR: Backtracking is not the "holy grail" for smarter LLMs. It’s praised for helping models “fix mistakes” and improve reasoning—but is it really the best use of test-time compute? 🤔

Transformer LMs get pretty far by acting like ngram models, so why do they learn syntax? A new paper by sunnytqin.bsky.social, me, and @dmelis.bsky.social illuminates grammar learning in a whirlwind tour of generalization, grokking, training dynamics, memorization, and random variation. #mlsky #nlp

Sometimes I am a Tree: Data Drives Unstable Hierarchical Generalization

Language models (LMs), like other neural networks, often favor shortcut heuristics based on surface-level patterns. Although LMs behave like n-gram models early in training, they must eventually learn...

arxiv.org