RUS  ENG
Full version
JOURNALS // Chelyabinskiy Fiziko-Matematicheskiy Zhurnal // Archive

Chelyab. Fiz.-Mat. Zh., 2025 Volume 10, Issue 1, Pages 112–125 (Mi chfmj426)

Mathematics

An analogue of Turaev comultiplication for knots in non-orientable thickening of a non-orientable surface

V. V. Tarkaevab

a Chelyabinsk State University, Chelyabinsk, Russia
b Krasovskii Institute of Mathematics and Mechanics of Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia

Abstract: This paper concerns pseudo-classical knots in the non-orientable manifold $\hat{\Sigma} =\Sigma \times [0,1]$, where $\Sigma$ is a non-orientable surface and a knot $K \subset \hat{\Sigma}$ is called pseudo-classical if $K$ is orientation-preserving path in $\hat{\Sigma}$. For this kind of knot we introduce an invariant $\Delta$ that is an analogue of Turaev comultiplication for knots in a thickened orientable surface. As its classical prototype, $\Delta$ takes value in a polynomial algebra generated by homotopy classes of non-contractible loops on $\Sigma$, however, as a ground ring we use some subring of $\mathbb{C}$ instead of $\mathbb{Z}$. Then we define a few homotopy, homology and polynomial invariants, which are consequences of $\Delta$, including an analogue of the affine index polynomial.

Keywords: knots in non-orientable manifold, knots in thickened surface, invariants of knots, Turaev comultiplication, affine index polynomial.

UDC: 515.162.8

Received: 30.07.2024
Revised: 08.12.2024

Language: English

DOI: 10.47475/2500-0101-2025-10-1-112-125



© Steklov Math. Inst. of RAS, 2025