Evaluating the Systematic Reasoning Abilities of Large Language Models through Graph Coloring
Alex Heyman, Joel Zylberberg
TL;DR
This study uses graph $k$-coloring as a controlled benchmark to probe the systematic reasoning capabilities of large language models (LLMs) and large reasoning models (LRMs). It benchmarks six models across five small-graph problem sets ($4 \le n \le 8$, $2 \le k \le 4$) and four semantic frames, incorporating difficulty metrics like greedy score $g$ and uncolorability types to assess problem hardness. Results show standard LLMs struggle with even simple instances (often $>60\%$ error in harder cases), while LRMs substantially reduce errors but do not reach perfect accuracy, particularly as problems demand more extensive possibility-space exploration. The findings highlight meaningful framing effects, substantial progress in LLM reasoning but persistent reliability limits, and significant computational costs, underscoring the need for architectural and training innovations alongside robust benchmarking to guide future AI development.
Abstract
Contemporary large language models are powerful problem-solving tools, but they exhibit weaknesses in their reasoning abilities which ongoing research seeks to mitigate. We investigate graph coloring as a means of evaluating an LLM's capacities for systematic step-by-step reasoning and possibility space exploration, as well as effects of semantic problem framing. We test Claude 3.5 Sonnet, Llama 3.1 405B, Gemini 1.5 Pro, GPT-4o, o1-mini, and DeepSeek-R1 on a dataset of $k$-coloring problems with $2 \leq k \leq 4$ and vertex count $4 \leq n \leq 8$, using partial algorithmic solvers to further categorize problems by difficulty. In addition to substantial but varying framing effects, we find that all models except o1-mini and R1 exhibit $>60\%$ error rates on difficult problem types in all frames ($>15\%$ for o1-mini and $>10\%$ for R1), and no model achieves perfect accuracy even in the simple domain of 2-coloring 4-vertex graphs. Our results highlight both the considerable recent progress in LLM systematic reasoning and the limits of its reliability, especially in relation to increasing computational costs. We expect that more complex graph coloring problems, and procedural generation of arbitrary-complexity reasoning problems more broadly, offer further untapped potential for LLM benchmarking.
