English

Numerical topology of the clique complex of the partition graph: Euler characteristic, clique counts, and sequence data

General Mathematics 2026-04-02 v1

Abstract

We study the numerical topology of the clique complex Kn=Cl(Gn)K_n=\mathrm{Cl}(G_n), where GnG_n is the partition graph on the set of integer partitions of nn. Building on the previously established homotopy equivalence KnbnS2K_n \simeq \vee^{\,b_n} S^2, we shift the focus from qualitative topology to its numerical content. Our main objects are the Euler characteristic χ(Kn)\chi(K_n), the derived sequence bn=χ(Kn)1b_n=\chi(K_n)-1, the clique counts cr(n)c_r(n), and several related maximal-simplex counts. We develop two exact counting languages for the same invariant. The first is the direct clique-counting formula χ(Kn)=r1(1)r1cr(n)\chi(K_n)=\sum_{r\ge 1}(-1)^{r-1}c_r(n), which expresses Euler characteristic through clique counts in the partition graph. The second is a nerve-side formula arising from the canonical good cover by distinct full star- and full top-simplices, which yields χ(Kn)=χ(Nn)\chi(K_n)=\chi(N_n), where NnN_n is the corresponding nerve. We further use the classification of maximal simplices into star-, top-, and edge-type pieces to formulate a local-to-global counting framework based on local admissibility data and global deduplication. The paper is primarily organizational and computational. It fixes a consistent counting dictionary, separates intrinsic global counts from auxiliary based counts, records exact data for the full main sequence package on 1n251\le n\le 25, and extends the low-dimensional clique-count layer through n=60n=60. We do not claim closed formulas for χ(Kn)\chi(K_n) or for the full family of clique counts. Rather, the paper provides a framework in which such questions can be studied systematically.

Keywords

Cite

@article{arxiv.2603.26656,
  title  = {Numerical topology of the clique complex of the partition graph: Euler characteristic, clique counts, and sequence data},
  author = {Fedor B. Lyudogovskiy},
  journal= {arXiv preprint arXiv:2603.26656},
  year   = {2026}
}

Comments

23 pages, 2 figures