Adaptivity Under Realizability Constraints: Comparing In-Context and Agentic Learning

Fuente: arXiv
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Main Authors: Kratsios, Anastasis, Neuman, A. Martina, Petersen, Philipp
Format: Preprint
Published: 2026
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author Kratsios, Anastasis
Neuman, A. Martina
Petersen, Philipp
author_facet Kratsios, Anastasis
Neuman, A. Martina
Petersen, Philipp
contents We compare in-context learning with fixed queries and agentic learning with adaptive queries for uniform approximation of task families. We consider two settings: an unrestricted regime, where querying and approximation are arbitrary functions, and a realizable regime, where we require these operations to be implemented by ReLU neural networks. In both settings, adaptivity never hinders approximation performance. However, this advantage can change when one passes from the unrestricted regime to the realizable regime. We identify four distinct approximation scenarios, each witnessed by an explicit task family: (a) no advantage of adaptivity; (b) an advantage in the unrestricted regime that persists under ReLU realizability; (c) an advantage that arises only under realizability; and (d) an advantage that disappears under realizability. This demonstrates that representational constraints interact profoundly with the effect of adaptivity.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04995
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Adaptivity Under Realizability Constraints: Comparing In-Context and Agentic Learning
Kratsios, Anastasis
Neuman, A. Martina
Petersen, Philipp
Machine Learning
Statistics Theory
41A65, 68T05, 68T07, 68T42, 68Q17, 62F35
We compare in-context learning with fixed queries and agentic learning with adaptive queries for uniform approximation of task families. We consider two settings: an unrestricted regime, where querying and approximation are arbitrary functions, and a realizable regime, where we require these operations to be implemented by ReLU neural networks. In both settings, adaptivity never hinders approximation performance. However, this advantage can change when one passes from the unrestricted regime to the realizable regime. We identify four distinct approximation scenarios, each witnessed by an explicit task family: (a) no advantage of adaptivity; (b) an advantage in the unrestricted regime that persists under ReLU realizability; (c) an advantage that arises only under realizability; and (d) an advantage that disappears under realizability. This demonstrates that representational constraints interact profoundly with the effect of adaptivity.
title Adaptivity Under Realizability Constraints: Comparing In-Context and Agentic Learning
topic Machine Learning
Statistics Theory
41A65, 68T05, 68T07, 68T42, 68Q17, 62F35
url https://arxiv.org/abs/2605.04995