activity
20122020
collaborators

9 papers

math.GT2020

Some comparisons of Blanchfield pairings and cohomology pairings of knots

Takefumi Nosaka

We study some comparison between a bilinear cohomology pairing in local coefficients and the Blanchfield pairing of a knot. We show that the former pairing is an -equivalent inv…

math.GT2020

Twisted Alexander invariants of knot group representations II; computation and duality

Takefumi Nosaka

Given a homomorphism from a link group to a group, we introduce a -class in another way, which is a generalization of the 1-variable Alexander polynomial. We compare the

math.GT2020

Twisted Alexander invariants of knot group representations

Takefumi Nosaka

Given a homomorphism from a knot group to a fixed group, we introduce an element of a -group, which is a generalization of (twisted) Alexander polynomials. We compare this $K_…

math.GT2019

Meta-nilpotent quotients of mapping-torus groups and two topological invariants of quadratic forms

Takefumi Nosaka

We determine the center of a meta-nilpotent quotient of a mapping-torus group. As a corollary, we introduce two invariants, which are quadratic forms, of knots and of mapping class…

math.GT2018

Schur Multipliers and Second Quandle Homology

Rhea Palak Bakshi, Dionne Ibarra, Sujoy Mukherjee +2

We define a map from second quandle homology to the Schur multiplier and examine its properties. Furthermore, we express the second homology of Alexander quandles in terms of exter…

math.GT2018

Twisted cohomology pairings of knots III; triple cup products

Takefumi Nosaka

Given a representation of a link group, we introduce a trilinear form, as a topological invariant. We show that, if the link is either hyperbolic or a knot with malnormality, then…