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Mind the Gap: Deep Learning Doesn't Learn Deeply (arxiv.org)
2 points by nyrikki on May 30, 2025 | hide | past | pdf | discuss on HN

In plain words: Instead of training a graph network on examples, they set its weights so it runs an algorithm exactly, then compare with trained versions. The comparison shows where training finds a faithful algorithm and where it fails, hinting that only parallel algorithms are easy to learn.

Abstract · Mind The Gap: Quantifying Mechanistic Gaps in Algorithmic Reasoning via Neural Compilation

This paper aims to understand how neural networks learn algorithmic reasoning by addressing two questions: How faithful are learned algorithms when they are effective, and why do neural networks fail to learn effective algorithms otherwise? To answer these questions, we use neural compilation, a technique that directly encodes a source algorithm into neural network parameters, enabling the network to compute the algorithm exactly. This enables comparison between compiled and conventionally learned parameters, intermediate vectors, and behaviors. This investigation is crucial for developing neural networks that robustly learn complexalgorithms from data. Our analysis focuses on graph neural networks (GNNs), which are naturally aligned with algorithmic reasoning tasks, specifically our choices of BFS, DFS, and Bellman-Ford, which cover the spectrum of effective, faithful, and ineffective learned algorithms. Commonly, learning algorithmic reasoning is framed as induction over synthetic data, where a parameterized model is trained on inputs, traces, and outputs produced by an underlying ground truth algorithm. In contrast, we introduce a neural compilation method for GNNs, which sets network parameters analytically, bypassing training. Focusing on GNNs leverages their alignment with algorithmic reasoning, extensive algorithmic induction literature, and the novel application of neural compilation to GNNs. Overall, this paper aims to characterize expressability-trainability gaps - a fundamental shortcoming in learning algorithmic reasoning. We hypothesize that inductive learning is most effective for parallel algorithms contained within the computational class \texttt{NC}.

Lucas Saldyt, Subbarao Kambhampati
arXiv:2505.18623 · cs.AI, cs.LG · submitted May 24, 2025 · updated Dec 6, 2025
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