Toward a Theory of Hierarchical Memory for Language Agents

Fuente: arXiv
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Main Authors: Talebirad, Yashar, Parsaee, Ali, Szepesvari, Csongor Y., Nadiri, Amirhossein, Zaiane, Osmar
Format: Preprint
Published: 2026
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author Talebirad, Yashar
Parsaee, Ali
Szepesvari, Csongor Y.
Nadiri, Amirhossein
Zaiane, Osmar
author_facet Talebirad, Yashar
Parsaee, Ali
Szepesvari, Csongor Y.
Nadiri, Amirhossein
Zaiane, Osmar
contents Many recent long-context and agentic systems address context-length limitations by adding hierarchical memory: they extract atomic units from raw data, build multi-level representatives by grouping and compression, and traverse this structure to retrieve content under a token budget. Despite recurring implementations, there is no shared formalism for comparing design choices. We propose a unifying theory in terms of three operators. Extraction ($α$) maps raw data to atomic information units; coarsening ($C = (π, ρ)$) partitions units and assigns a representative to each group; and traversal ($τ$) selects which units to include in context given a query and budget. We identify a self-sufficiency spectrum for the representative function $ρ$ and show how it constrains viable retrieval strategies (a coarsening-traversal coupling). Finally, we instantiate the decomposition on eleven existing systems spanning document hierarchies, conversational memory, and agent execution traces, showcasing its generality.
format Preprint
id arxiv_https___arxiv_org_abs_2603_21564
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Toward a Theory of Hierarchical Memory for Language Agents
Talebirad, Yashar
Parsaee, Ali
Szepesvari, Csongor Y.
Nadiri, Amirhossein
Zaiane, Osmar
Information Retrieval
Artificial Intelligence
Information Theory
Social and Information Networks
Many recent long-context and agentic systems address context-length limitations by adding hierarchical memory: they extract atomic units from raw data, build multi-level representatives by grouping and compression, and traverse this structure to retrieve content under a token budget. Despite recurring implementations, there is no shared formalism for comparing design choices. We propose a unifying theory in terms of three operators. Extraction ($α$) maps raw data to atomic information units; coarsening ($C = (π, ρ)$) partitions units and assigns a representative to each group; and traversal ($τ$) selects which units to include in context given a query and budget. We identify a self-sufficiency spectrum for the representative function $ρ$ and show how it constrains viable retrieval strategies (a coarsening-traversal coupling). Finally, we instantiate the decomposition on eleven existing systems spanning document hierarchies, conversational memory, and agent execution traces, showcasing its generality.
title Toward a Theory of Hierarchical Memory for Language Agents
topic Information Retrieval
Artificial Intelligence
Information Theory
Social and Information Networks
url https://arxiv.org/abs/2603.21564