Can LLMs Reason Structurally? An Evaluation via the Lens of Data Structures

ICLR 2026 Conference Submission13455 Authors

Keywords: Algorithmic reasoning, LLM, evaluation, benchmark, data structure

TL;DR: DSR-Bench is a novel benchmark that isolates and evaluates LLMs’ structural reasoning, using data structures as an interpretable lens to understand algorithmic reasoning.

Abstract: As large language models (LLMs) take on increasingly complex tasks, understanding their algorithmic reasoning abilities has become essential. However, existing evaluations focus on distinct and isolated tasks. We propose a unified diagnostic lens: structural reasoning—understanding and manipulating relationships like order, hierarchy, and connectivity. We introduce DSR-Bench, the first benchmark to systematically evaluate LLM structural reasoning through canonical data structures, which serve as interpretable, algorithmically meaningful abstractions. DSR-Bench spans 20 data structures, 35 operations, and 4,140 synthetically generated problem instances with minimal contamination. The benchmark’s hierarchical design pinpoints specific failure modes, while its fully automated evaluation ensures objective and consistent assessment. Benchmarking ten state-of-the-art LLMs reveals critical limitations: the top-performing model scores only 0.498 out of 1 on challenging instances. Three additional evaluation suites reveal further weaknesses: models perform poorly on spatial data and natural language scenarios, and fail to reason over their own generated code. DSR-Bench offers a principled diagnostic tool for structural reasoning, helping expose reasoning bottlenecks and guide the development of more capable and reliable LLMs.

Primary Area: datasets and benchmarks

Submission Number: 13455