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Combinatorial correlation functions in three-dimensional eight-vertex models

Igor G. Korepanov

TL;DR

The paper develops an explicit ${\mathbb F}_2$-linear i-to-${\it t}$ spin transform for a 3D combinatorial eight-vertex model, enabling exact calculation of spin correlations on $2^n\times2^n\times2^n$ blocks under cyclic boundaries. By constructing new thick-space bases and a tensor-product transform, it reduces multi-spin probabilities to tractable Fourier-analytic expressions governed by the eigenstructure of a $3\times3$ matrix $A$ over ${\mathbb F}_2$ (and its transpose). For a concrete $A$, the authors compute single-, pair-, triple-, and quadruple-spin probabilities, revealing mostly independence for small spins but revealing nontrivial 4-spin correlations in structured configurations. The approach generalizes to multiple $A$ choices, preserving key correlation structures, and opens a pathway to rigorous analysis of 3D combinatorial spin systems without integrability assumptions. The results illustrate how algebraic self-similarity and Fourier methods yield exact, scalable insights into complex 3D spin correlation phenomena in a purely combinatorial setting.

Abstract

A new version of the self-similarity spin transform on three-dimensional cubic lattices is proposed that makes possible calculation of nontrivial spin correlations in a "combinatorial" model, in which all permitted spin configurations have equal probabilities.

Combinatorial correlation functions in three-dimensional eight-vertex models

TL;DR

The paper develops an explicit -linear i-to- spin transform for a 3D combinatorial eight-vertex model, enabling exact calculation of spin correlations on blocks under cyclic boundaries. By constructing new thick-space bases and a tensor-product transform, it reduces multi-spin probabilities to tractable Fourier-analytic expressions governed by the eigenstructure of a matrix over (and its transpose). For a concrete , the authors compute single-, pair-, triple-, and quadruple-spin probabilities, revealing mostly independence for small spins but revealing nontrivial 4-spin correlations in structured configurations. The approach generalizes to multiple choices, preserving key correlation structures, and opens a pathway to rigorous analysis of 3D combinatorial spin systems without integrability assumptions. The results illustrate how algebraic self-similarity and Fourier methods yield exact, scalable insights into complex 3D spin correlation phenomena in a purely combinatorial setting.

Abstract

A new version of the self-similarity spin transform on three-dimensional cubic lattices is proposed that makes possible calculation of nontrivial spin correlations in a "combinatorial" model, in which all permitted spin configurations have equal probabilities.
Paper Structure (37 sections, 10 theorems, 72 equations, 4 figures)

This paper contains 37 sections, 10 theorems, 72 equations, 4 figures.

Key Result

Proposition 1

$2\times 2\times 2$ block of matrices $A$ (such as in Figure f:b222) acts on rows of vector coordinates in bases new21, nm according to tildes (where, as we remember, $\tilde{A}$ is obtained from $A$ by the Frobenius isomorphism $a_{ij} \mapsto a_{ij}^2$ of all its entries).

Figures (4)

  • Figure 1: $2\times 2\times 2$ block. At each vertex, $3\times 3$ matrix $A$ transforms the row of three input field $F$ elements into the row of three output elements. The positions in a row correspond (in a fixed way) to three edge directions. Field $F=\mathbb F_2$ almost everywhere in this paper
  • Figure 2: LHS: Input of a $2\times 2\times 2$ block, perpendicular to axis 1. Directions of axes 2 and 3 are $\downarrow$ and $\rightarrow$, respectively. RHS: Four separate inputs after switching to basis \ref{['new21']}. Here $\downarrow$ and $\rightarrow$ are directions of the ghost axes $\alpha$ and $\beta$
  • Figure 3: General pictorial representation for a transform of four inputs
  • Figure 4: The second step of transforms in a $4\times 4$ square

Theorems & Definitions (22)

  • Remark
  • Proposition 1
  • proof
  • Proposition 2
  • proof
  • Proposition 3
  • proof
  • Remark
  • Proposition 4
  • proof
  • ...and 12 more