HyperSkill: Self-Evolving LLM Agents via Hypergraph-Structured Skill Memory

AuthorsRuiyao Xu, Tiankai Yang, Wei-Chieh Huang

arXiv 20262026

TL;DR

HYPERSKILL uses hypergraph-structured skill memory with dual-path retrieval and structure-informed maintenance to reach 62.00% SR on xBench with GPT-4o (+3.00 over PlugMem).

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THE PROBLEM

Experiential memories lose compositional structure and relational signals

Existing experiential memories store trajectories, workflows, or skills as isolated entries, discarding compositional relationships among subtasks and reusable skills.

Most systems rely on flat vector similarity and unconditional accumulation, so agents retrieve noisy, unstructured memories that limit self-evolving performance on complex multi-step tasks.

HOW IT WORKS

HYPERSKILL hypergraph memory with dual-path retrieval

HYPERSKILL’s core mechanism combines Nodes, Hyperedges, Dual-path retrieval, Co-occurrence ranking, and HYPERSKILL Memory Evolving into a single hypergraph-structured memory.

You can think of HYPERSKILL like a card catalog where each card links a whole episode’s subtasks and skills, instead of storing isolated pages in a filing cabinet.

This hypergraph design lets HYPERSKILL reuse procedural structure and quality-weighted skills far beyond what a plain context window or flat vector store can capture.

DIAGRAM

Query time flow from task to skills and lessons

This diagram shows how HYPERSKILL processes a new task using subtask and trajectory paths, then ranks skills by co-occurrence for execution.

DIAGRAM

Evaluation setup across xBench, GAIA, and WebWalkerQA

This diagram shows how HYPERSKILL is evaluated with two backbones and multiple memory baselines on three benchmarks.

PROCESS

How HYPERSKILL Handles a Task Episode

  1. 01

    Task decomposition and subtask path

    HYPERSKILL uses Task decomposition and subtask path to turn the task description dq into a fine grained plan P0 aligned with subtask nodes Vu.

  2. 02

    From Subtasks to Trajectories Hyperedge Retrieval

    Using From Subtasks to Trajectories Hyperedge Retrieval, HYPERSKILL matches P0 and dq against hyperedge embeddings he to form the fused set E star.

  3. 03

    From Trajectories to Skills Skill Retrieval

    In From Trajectories to Skills Skill Retrieval, HYPERSKILL aggregates skill nodes from E star and applies Co-occurrence ranking via κ v to select Sq.

  4. 04

    HYPERSKILL Memory Evolving

    During HYPERSKILL Memory Evolving, HYPERSKILL applies quality driven pruning and structure informed merging using the co occurrence matrix W and propagated embeddings Z tilde.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Hypergraph structured experiential memory

    HYPERSKILL introduces Nodes and Hyperedges where each trajectory hyperedge groups subtasks Vu and skills Vs with a distilled lesson and utility score γ, preserving n ary associations.

  • 02

    Dual path retrieval and co occurrence ranking

    HYPERSKILL combines Dual-path retrieval over subtasks and trajectories with Co-occurrence ranking, selecting skills by κ v across retrieved hyperedges instead of pure embedding similarity.

  • 03

    Structure informed maintenance for self evolving agents

    HYPERSKILL’s HYPERSKILL Memory Evolving performs quality driven pruning with τprune=0.2 and structure informed merging using quality weighted co occurrence matrix W and propagation depth L.

RESULTS

By the Numbers

SR xBench GPT 4o

62.00%

+3.00 over PlugMem

SR GAIA GPT 4o

44.24%

+2.30 over PlugMem

SR WebWalkerQA Qwen3 30B

50.59%

+4.71 over MemP

Avg Steps xBench GPT 4o

5.27 steps

matches ExpeL with higher SR

On xBench, GAIA, and WebWalkerQA, which test tool augmented planning and web navigation, HYPERSKILL consistently raises success rate while keeping steps and tool calls competitive with baselines. These numbers show that hypergraph structured skill memory yields higher task success without inflating interaction cost.

BENCHMARK

By the Numbers

On xBench, GAIA, and WebWalkerQA, which test tool augmented planning and web navigation, HYPERSKILL consistently raises success rate while keeping steps and tool calls competitive with baselines. These numbers show that hypergraph structured skill memory yields higher task success without inflating interaction cost.

BENCHMARK

Main results on xBench with GPT 4o

Success Rate SR on xBench for HYPERSKILL and representative memory baselines using GPT 4o.

BENCHMARK

Main results on GAIA with GPT 4o

Success Rate SR on GAIA for HYPERSKILL and representative memory baselines using GPT 4o.

KEY INSIGHT

The Counterintuitive Finding

HYPERSKILL achieves its best performance with a very small retrieval budget, with k=2 giving 62.0% SR on xBench and 51.2% on WebWalkerQA.

This is surprising because many assume more retrieved memories always help, but HYPERSKILL shows that larger k mainly injects noise and degrades success rate.

WHY IT MATTERS

What this unlocks for the field

HYPERSKILL unlocks self evolving agents that reuse compositional workflows and skills through hyperedges, instead of hoarding flat, noisy trajectory logs.

Builders can now deploy long lived agents whose memory stays compact, high quality, and structurally aware, enabling continual improvement across diverse web and tool use tasks.

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