activity
20242026
collaborators

4 papers

math.GT2026

Blanchfield pairings and twisted Blanchfield pairings of torus knots

Koki Yanagida

We give explicit matrix presentations of the Blanchfield pairing and certain twisted Blanchfield pairings of the -torus knot . Our method uses a taut identity realiz…

math.GT2025

Parabolic Dijkgraaf-Witten invariants of links in the -sphere

Koki Yanagida

We define a new invariant of links in the -sphere and call it the parabolic Dijkgraaf-Witten (DW) invariant. This invariant is a generalization of the reduced DW invariant deriv…

math.GT2025

Dijkgraaf-Witten invariant in topological -theory

Koki Yanagida

Given a finite group , we define a new invariant of odd-dimensional oriented closed manifolds and call it the KDW invariant. This invariant is a Dijkgraaf--Witten invariant in t…

math.GT2024

Nonacyclic Reidemeister torsions of manifolds of odd dimension

Takefumi Nosaka, Koki Yanagida, Naoko Wakijo

Given an oriented closed manifold of odd dimension and a unitary representation $ρ: π_1(M) \ra \GL_n(\F)$, we define a Reidemeister torsion, even if the cohomology associated…