arXiv subjects

Kentaro Yamaguchi

Publications and source records attributed to Kentaro Yamaguchi.

5 recordsLinked to original sources

arXiv2026

Decompositions of good involutions on quandles

We study the behavior of good involutions under two fundamental constructions of quandles: interaction-free unions and direct products. In particular, we show that the set of good involutions on a quandle decomposes naturally into the set of involutions on its maximal trivial component and the set of good involutions on the complement. Moreover, we construct an example of a connected noninvolutory symmetric quandle with multiple good involutions, which serves as a counterexample to a conjecture by Ta.

math.GT↗

arXiv2026

On the nonexistence of good involutions of symplectic quandles

We investigate the necessary and sufficient condition for the existence of good involutions of symplectic quandles, which are defined on free $R$-modules with an antisymmetric bilinear form. In particular, we discuss the nonexistence of good involutions of symplectic quandles.

math.GT↗

arXiv2024

Delzant type theorem for torus-equivariantly embedded toric hypersurfaces

In the previous work, we study the moment polytope of the closure of the complex subtorus orbit in a symplectic toric manifold associated to an affine subspace when the closure is a smooth complex submanifold. In this paper, we clarify the condition for nonsingularity of the closure of the codimension one complex subtorus orbit in terms of polytopes. The main result is a generalization of Delzant theorem.

math.SG↗

arXiv2024

Submanifolds with corners in Delzant polytopes associated to affine subspaces

We studied the closure of a complex subtorus given from an affine subspace in $\mathfrak{t}^{n} \cong \mathbb{R}^{n}$ in a toric manifold. If the closure of the complex subtorus is a smooth complex submanifold in the toric manifold, then we call such submanifold a torus-equivariantly embedded toric manifold with respect to the subtorus action determined by the data of the affine subspace. In this paper, we construct certain submanifolds with corners in a Delzant polytope of the toric manifold from the affine subspaces and show that the conditions for such submanifolds with corners are equivalent to those for torus-equivariantly embedded toric manifolds.

math.SG↗

arXiv2023

Torus-equivariantly embedded toric manifolds associated to affine subspaces

We study the closure of a complex subtorus in a toric manifold. If the closure of the complex subtorus is a smooth complex submanifold in the toric manifold, then the subtorus action on such submanifold is Hamiltonian. In this case, we may think of the embedding of the submanifold as torus-equivariant. We show that the image of the moment map for the Hamiltonian subtorus action on our submanifold coincides with the image of the Delzant polytope of the ambient toric manifold under the pullback of the inclusion of the tori. The submanifolds constructed in the present paper are called torus-equivariantly embedded toric manifolds with respect to the subtorus action.

math.SG↗