Tropical Degenerations of Network Games:Valuation Classes and Equilibrium Coalescence

TL;DR

This paper develops a valuation-theoretic framework for analyzing tropical degenerations in network games, revealing how equilibrium structures and counts are affected by algebraic and scheme-theoretic degenerations.

Contribution

It introduces a novel valuation-based approach to study tropical degenerations and equilibrium coalescence in multilinear network games, connecting algebraic and scheme-theoretic invariants.

Findings

Valuation classes organize Puiseux equilibrium branches under degeneration.

Binomial reductions are governed by exponent-difference graphs and lattice indices.

Valuation coalescence corresponds to intrinsic scheme-theoretic collisions, refining equilibrium counts.

Abstract

A valuation-theoretic framework is developed for studying tropical degenerations of multilinear network games. Equilibrium conditions are modeled by an ideal over the Puiseux field, and valuation classes and cluster multiplicities are used to describe the organization of Puiseux equilibrium branches under degeneration. For valuation vectors lying in the relative interiors of generator-wise maximal tropical cells, multilinearity is shown to force a binomial reduction of the generator-wise initial system. The resulting binomial systems are governed by exponent-difference graphs, strongly connected component decompositions, and lattice indices computed via Smith normal form. In particular, unimodular diagonal blocks yield initial-coefficient rigidity, whereas non-unimodular blocks give rise to torsion-type leading-coefficient multiplicities. The generic binomial theory is complemented by a collision-normalized cross-prism family. In this family, 2^L Puiseux equilibrium branches share the same valuation vector and the same leading-coefficient vector. The corresponding limiting initial fiber is supported at a single torus point, but this point is nonreduced with scheme-theoretic length 2^L. Thus valuation coalescence is realized as an intrinsic scheme-theoretic collision rather than merely as a loss of higher-order terms. These local degeneration invariants are then related to the algebraic-degree theory of network games, showing how global equilibrium counts can be refined by valuation classes, binomial initial systems, Smith lattice data, and nonreduced collision fibers.