arXiv AI

Measuring in-context algorithmic reasoning in language models against an exact Bayes-optimal reference

The paper introduces F-ICL, a benchmark that measures in‑context algorithmic reasoning in language models by exhaustively enumerating 86 million valid programs of length ≤13 on a Turing‑complete machine and computing the exact posterior under a bounded Levin–Solomonoff prior. Unlike typical benchmarks, F‑ICL provides a distributional reference rather than just answers, allowing the evaluation of models’ inductive priors. Across 105 configurations of models ranging from 0.8 B to 675 B parameters, models achieve up to 92 % accuracy, yet many still deviate from the Bayes‑optimal reference, and the study derives theoretical bounds on cumulative loss for predictors with positive prior weight on the reference.

arXiv Machine Learning
Oct 3

Large Language Bayes Is Not Reparameterisation-Invariant

Large Language Bayes (LLB) samples probabilistic programs from a language model, runs approximate inference on each, and averages them weighted by an exponentiated evidence bound. The authors demonstrate that this weighting is not invariant to reparameterisation, unlike the log marginal likelihood, leading to significant discrepancies in weights across different program formulations. These discrepancies can reach up to 31.9×, affect Bayes factors, and introduce controlled errors in posterior estimates.

By Jian Xu
arXiv AI
Sep 3

Language Models Can Control Their Own Attention

The paper introduces Declarative Attention (DA), a protocol that lets language models explicitly declare which parts of their context to focus on during generation. By partitioning decoding into full-context, region-specific, and recent-output-only modes, the inference engine can skip large portions of the KV cache, dramatically reducing attended tokens. Experiments on 15 long-context tasks with off-the-shelf models show significant savings (52.0% and 31.1% reductions) with only modest accuracy drops that diminish as model size increases.

By Namgyu Ho, Huzama Ahmad, Woosung Koh, Se-Young Yun, Tal Schuster, Cicero Nogueira dos Santos
arXiv AI
Oct 9

SFT-as-Context Mitigates Forgetting in Supervised Fine-Tuning

The paper introduces SFT-as-context, a training‑free method that lets a parent large language model (LLM) use the response of a supervised fine‑tuned (SFT) model as context to answer queries. This approach preserves the parent model’s general capabilities while acquiring the SFT model’s specialized skills, achieving performance close to the SFT model on fine‑tuned benchmarks and near the parent model on general tasks. Experiments across 19 parent‑SFT pairs and 11 benchmarks show minimal gaps in performance, and the method can solve problems requiring both specialized and general knowledge, even when neither model alone succeeds.

By Kenan Tang, Andong Hua, Chengxuan Qian, Saket Tiwari, Yao Qin