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Axial Morphology of the Partition Graph: Self-Conjugate Axis, Spine, and Concentration

Fedor B. Lyudogovskiy

Abstract

We study the partition graph $G_n$, whose vertices are the partitions of $n$ and whose edges correspond to elementary unit transfers between parts. We define the self-conjugate axis, its distance neighborhoods, and the thin spine, a first off-axis layer built from common neighbors of distinct axial vertices. We prove that distinct self-conjugate vertices are never adjacent, that the thin spine is a conjugation-invariant induced subgraph, and that axial and spinal concentration radii differ by at most one. Computations for $1 \le n \le 30$ show that the main local invariants are maximized near the axis and the spine.

Axial Morphology of the Partition Graph: Self-Conjugate Axis, Spine, and Concentration

Abstract

We study the partition graph , whose vertices are the partitions of and whose edges correspond to elementary unit transfers between parts. We define the self-conjugate axis, its distance neighborhoods, and the thin spine, a first off-axis layer built from common neighbors of distinct axial vertices. We prove that distinct self-conjugate vertices are never adjacent, that the thin spine is a conjugation-invariant induced subgraph, and that axial and spinal concentration radii differ by at most one. Computations for show that the main local invariants are maximized near the axis and the spine.
Paper Structure (53 sections, 18 theorems, 95 equations, 2 figures)

This paper contains 53 sections, 18 theorems, 95 equations, 2 figures.

Key Result

Proposition 2.1

The map is an involutive graph automorphism of $G_n$.

Figures (2)

  • Figure 1: Smaller representative examples of axial morphology for $n=5,6,8,9,12,13$.
  • Figure 2: Larger representative examples of axial morphology for $n=19,24,29,30$.

Theorems & Definitions (60)

  • Proposition 2.1
  • proof
  • Definition 2.2
  • Remark 2.3
  • Remark 2.4
  • Remark 2.5
  • Definition 2.6
  • Definition 2.7
  • Lemma 2.8
  • proof
  • ...and 50 more