Elliptic curves in game theory

Fuente: arXiv
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Hauptverfasser: Kidambi, Abhiram, Neuhaus, Elke, Portakal, Irem
Format: Preprint
Veröffentlicht: 2025
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author Kidambi, Abhiram
Neuhaus, Elke
Portakal, Irem
author_facet Kidambi, Abhiram
Neuhaus, Elke
Portakal, Irem
contents We investigate Spohn curves, the algebro-geometric models of totally mixed dependency equilibria for $2 \times 2$ normal-form games. These curves arise as the intersection of two quadrics in $\mathbb{P}^3$ and are generically elliptic curves. We examine the reduction of Spohn curves to plane curves, providing a full classification of conditions under which they are reducible. Notably, we prove that the real points are dense on the Spohn curve in all cases, which is relevant for applications. These computations are further supported by Macaulay2 and stored in Mathrepo. We review methods to compute the $j$-invariants of elliptic curves arising as the intersection of quadrics in $\mathbb P^3$ which we apply to the case of Spohn curves aimed at game theorists. We propose a definition of equivalence of generic $2\times 2$ games based on the $j$-invariant of the Spohn curve.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14612
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Elliptic curves in game theory
Kidambi, Abhiram
Neuhaus, Elke
Portakal, Irem
Algebraic Geometry
91B52, 91A05, 14P05, 14H52, 14Q05
We investigate Spohn curves, the algebro-geometric models of totally mixed dependency equilibria for $2 \times 2$ normal-form games. These curves arise as the intersection of two quadrics in $\mathbb{P}^3$ and are generically elliptic curves. We examine the reduction of Spohn curves to plane curves, providing a full classification of conditions under which they are reducible. Notably, we prove that the real points are dense on the Spohn curve in all cases, which is relevant for applications. These computations are further supported by Macaulay2 and stored in Mathrepo. We review methods to compute the $j$-invariants of elliptic curves arising as the intersection of quadrics in $\mathbb P^3$ which we apply to the case of Spohn curves aimed at game theorists. We propose a definition of equivalence of generic $2\times 2$ games based on the $j$-invariant of the Spohn curve.
title Elliptic curves in game theory
topic Algebraic Geometry
91B52, 91A05, 14P05, 14H52, 14Q05
url https://arxiv.org/abs/2501.14612