Secondary Stiefel-Whitney numbers and corresponding cobordism groups

TL;DR

This paper introduces new invariants related to Stiefel-Whitney numbers, constructs extended cobordism groups, and demonstrates that these invariants fully classify certain cobordism classes of manifolds.

Contribution

It defines the invariant ppa_R for null-cobordant manifolds, constructs the cobordism group mbda_n^R extending mbda_n^O, and proves ppa_R's completeness and quadratic nature.

Findings

ppa_R equals the Kervaire semi-characteristic for specific cases.

Constructed the cobordism group mbda_n^R extending unoriented cobordism.

Proved ppa_R is a complete invariant of R-cobordism classes.

Abstract

For every relation $R$ between Stiefel-Whitney numbers of closed $(n+1)$-manifolds we consider an associated invariant $\varkappa_R$ of null-cobordant $n$-manifolds with a certain additional structure. For $n=2k-1$ and $R = w_{n+1}+v_k^2$ the invariant $\varkappa_R$ equals the Kervaire semi-characteristic. In addition, we construct the cobordism group $\Omega_n^R$, which extends the unoriented cobordism group $\Omega_n^O$. We show that $\varkappa_R$ is a complete invariant of $R$-cobordism classes of null-cobordant $n$-manifolds. We prove that our invariant $\varkappa_R$ and $R$-cobordism class of manifold are quadratic in the sense of Gusarov-Vassiliev-Podkorytov.