7 papers
Topological line arrangements and their topological invariants
Sakumi Sugawara
A topological line arrangement is an arrangement of embedded spheres in the complex projective plane that topologically generalizes a complex line arrangement. In this paper, we es…
Handle decompositions and Kirby diagrams for the complement of plane algebraic curves
Sakumi Sugawara
The complement of plane algebraic curves are well studied from topological and algebro-geometric viewpoints. In this paper, we will describe the explicit handle decompositions and…
Even torsions in the homology group of the Milnor fiber boundary of hyperplane arrangements in
Sakumi Sugawara
We study the homology group of the Milnor fiber boundary of a hyperplane arrangement in . By the work of Némethi--Szilárd, the homeomorphism type of the Milnor fi…
First homology groups of the Milnor fiber boundary for generic hyperplane arrangements in
Sakumi Sugawara
We study the Milnor fiber boundary for hyperplane arrangements in . This is one of the examples of non-isolated surface singularities, which are studied by Némethi--…
The cohomology ring of the boundary manifold of a combinatorial line arrangement
Sakumi Sugawara
We compute the integral cohomology rings of the associated -manifold called the \textit{boundary manifold} for a combinatorial line arrangement, and prove that it is isomorphic…
Homogeneous quandles with abelian inner automorphism groups
Takuya Saito, Sakumi Sugawara
In this paper, we give a characterization of homogeneous quandles with abelian inner automorphism groups. In particular, we show that such a quandle is expressed as an abelian exte…