arXiv Computation and Language

LAMB: Latent Multi-Hypothesis Beliefs for Long-Horizon Large Language Agents

The paper introduces LAMB, a recurrent framework that stores latent multi‑hypothesis beliefs for long‑horizon language agents. LAMB separates a shared Common state containing interaction evidence from weighted Delta components representing competing hypotheses, and updates these hypotheses using relative evidence from action‑outcome predictions without generating textual memory. Experiments on ALFWorld, BabyAI, ScienceWorld, and Crafter show that LAMB matches or surpasses prior methods, notably improving success rates and reducing redundant actions.

arXiv AI
Oct 2

Beyond Memory: Harnessing Long-Horizon Agents with Explicit Belief States

Beyond Memory: Harnessing Long-Horizon Agents with Explicit Belief States introduces PoS, an inference-time framework that builds and maintains explicit belief states to guide large language model agents. Each belief state combines an estimate of the current world with unresolved task requirements, making clear what the agent still needs to learn and accomplish. PoS validates consistency, monitors task progress to detect Belief Trapping, and tailors recovery to the trapping pattern and unresolved requirements, achieving top performance across four benchmarks with all three LLM backbones.

By Yu Luo, Jiamin Jiang, Yimin Zuo, Xidao Wen, Rongchen Gao, Yongqian Sun, Shenglin Zhang, Guiyang Liu, Cheng Zhang, Fang Situ, Qi Zhou, Dan Pei
arXiv Computation and Language
Oct 1

LatentHarness: Learning Latent Actions for Memory and Reasoning via Counterfactual Policy Distillation

LatentHarness unifies memory access and latent reasoning by treating them as sequential latent actions—THINK, RECALL, and EXIT—within a language model. It is trained via counterfactual policy distillation, which evaluates the impact of each action on the emitted token and learns when to recall evidence versus continue reasoning. On six long‑context reasoning benchmarks, a 1.4B‑parameter LatentHarness model outperforms the strongest baselines by 2.8% and 10.0% relative, while running 5.9× faster than the leading long‑context baseline.

By Xiaoqiang Wang, Suyuchen Wang, Bang Liu
arXiv Machine Learning
Jun 29

Textual Belief States for World Models: Identifiable Representation Learning Under Strict Mediation

arXiv:2606. 27681v1 Announce Type: new Abstract: World models in partially observed environments rely on latent representations that summarize interaction history, but in many modern LLM-based architectures predictive performance fails to reflect representation quality due to history bypass, rendering the latent state unidentifiable.

By Xiang Gao, Kaiwen Dong, Yuguang Yao, Padmaja Jonnalagedda, Kamalika Das
arXiv AI
Sep 30

CoEM: Empowering Long-Context Reasoning with Commit-on-Evidence Memory

CoEM introduces a Commit-on-Evidence Memory system that learns when to compress source evidence into compact memory facts while preserving potentially useful excerpts verbatim in a pending set. The system uses a learned policy to decide whether to promote, retain, or discard each pending excerpt as new context arrives, and a frozen verifier ensures only supported facts are committed. Reinforcement learning trains this policy with step-level evidence rewards and final answer rewards, leading to consistent improvements in long-context reasoning, achieving 10.4–11.4 F1 points over the strongest baseline on 6,400-document inputs.

By Jingguang Li, Yebo Wu, Zuyi Guo, Kailang Ma, Xianjie Dai, Han Zheng, Benwang Chen, Li Li, Can Rong, Heye Huang
arXiv AI
Jun 10

Fact-Augmented Lookahead Planning for LLM Agents

arXiv:2506. 09171v2 Announce Type: replace-cross Abstract: Large Language Models (LLMs) are increasingly capable, but LLM agents still struggle to plan effectively in interactive, partially observable, long-horizon environments when search is unguided or recent history is insufficient.

By Samuel Holt, Max Ruiz Luyten, Thomas Pouplin, Mihaela van der Schaar
arXiv AI
Oct 2

JevSpawn: Adaptive Agentic Inference through Compositional Action Spaces

JevSpawn is a new compositional policy that links natural language task specifications to finite probabilistic exploration, enabling LLM agents to generate actions more efficiently. It uses parallel action spawning, feedback‑driven branch selection, representation revision, and recovery from retained alternatives to adapt actions during interaction. Evaluations on eight benchmark tasks show that JevSpawn outperforms seven agent baselines and a TypeSafe Jev variant, improving task performance and speeding navigation.

By Haoyang Su, Weiran Huang