A Note on the Eilenberg-Mac Lane Isomorphism for Quadratic Forms

César Galindo

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arXiv · 2507.15726

A Note on the Eilenberg-Mac Lane Isomorphism for Quadratic Forms

César Galindo

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Abstract

We give an elementary proof of the Eilenberg-Mac Lane trace isomorphism between the third 2-abelian cohomology group and quadratic forms. Our approach yields explicit constructions and we characterize when quadratic forms can be expressed as traces of bilinear forms for arbitrary coefficient groups.

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César Galindo. 2025-07-21. A Note on the Eilenberg-Mac Lane Isomorphism for Quadratic Forms. https://arxiv.org/abs/2507.15726

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