15 citations · 59 across the 20 of their papers we have counts for
20 papers
Semidirect Product Decompositions for Periodic Regular Languages
Yusuke Inoue, Kenji Hashimoto, Hiroyuki Seki
The definition of period in finite-state Markov chains can be extended to regular languages by considering the transitions of DFAs accepting them. For example, the language $(ΣΣ)^*…
Free automorphism groups of K3 surfaces with Picard number 3
Kenji Hashimoto, Kwangwoo Lee
It is known that the automorphism group of any projective K3 surface is finitely generated [24]. In this paper, we consider a certain kind of K3 surfaces with Picard number 3 whose…
Characterizing Attributed Tree Translations in Terms of Macro Tree Transducers
Kenji Hashimoto, Sebastian Maneth
It is well known that attributed tree transducers can be equipped with "regular look-around" in order to obtain a more robust class of translations. We present two characterization…
Solving Rep-tile by Computers: Performance of Solvers and Analyses of Solutions
Mutsunori Banbara, Kenji Hashimoto, Takashi Horiyama +7
A rep-tile is a polygon that can be dissected into smaller copies (of the same size) of the original polygon. A polyomino is a polygon that is formed by joining one or more unit sq…
Extensions of maximal symplectic actions on K3 surfaces
Simon Brandhorst, Kenji Hashimoto
We classify pairs consisting of a complex K3 surface and a finite group such that the subgroup consisting of symplectic automorphisms is a…
On the Compositionality of Dynamic Leakage and Its Application to the Quantification Problem
Bao Trung Chu, Kenji Hashimoto, Hiroyuki Seki
Quantitative information flow (QIF) is traditionally defined as the expected value of information leakage over all feasible program runs and it fails to identify vulnerable program…
Quantifying Dynamic Leakage: Complexity Analysis and Model Counting-based Calculation
Bao Trung Chu, Kenji Hashimoto, Hiroyuki Seki
A program is non-interferent if it leaks no secret information to an observable output. However, non-interference is too strict in many practical cases and quantitative information…
Examples of non-Kähler Calabi-Yau 3-folds with arbitrarily large
Kenji Hashimoto, Taro Sano
We construct non-Kähler simply connected Calabi-Yau 3-folds with arbitrarily large 2nd Betti numbers by smoothing normal crossing varieties with trivial dualizing sheaves.
Reconstruction of general elliptic K3 surfaces from their Gromov-Hausdorff limits
Kenji Hashimoto, Kazushi Ueda
We show that a general elliptic K3 surface with a section is determined uniquely by its discriminant, which is a configuration of 24 points on the projective line. It follows that…
K3 surfaces with Picard number 2, Salem polynomials and Pell equation
Kenji Hashimoto, JongHae Keum, Kwangwoo Lee
If an automorphism of a projective K3 surface with Picard number 2 is of infinite order, then the automorphism corresponds to a solution of Pell equation. In this paper, by solving…
Calabi-Yau threefolds of type K (II): Mirror symmetry
Kenji Hashimoto, Atsushi Kanazawa
A Calabi-Yau threefold is called of type K if it admits an étale Galois covering by the product of a K3 surface and an elliptic curve. In our previous paper, based on Oguiso-Sakura…
On a certain generalization of triangle singularities
Kenji Hashimoto, Hwayoung Lee, Kazushi Ueda
Triangle singularities are Fuchsian singularities associated with von Dyck groups, which are index two subgroups of Schwarz triangle groups. Hypersurface triangle singularities are…
Calabi-Yau threefolds of type K (I): Classification
Kenji Hashimoto, Atsushi Kanazawa
Any Calabi-Yau threefold X with infinite fundamental group admits an étale Galois covering either by an abelian threefold or by the product of a K3 surface and an elliptic curve. W…
The ring of modular forms for the even unimodular lattice of signature (2,10)
Kenji Hashimoto, Kazushi Ueda
We show that the ring of modular forms with characters for the even unimodular lattice of signature (2,10) is generated by forms of weights 4, 10, 12, 16, 18, 22, 24, 28, 30, 36, 4…
Modular surfaces associated with toric K3 hypersurfaces
Kenji Hashimoto, Atsuhira Nagano, Kazushi Ueda
We give detailed descriptions of the period maps of two 2-parameter families of anti-canonical hypersurfaces in toric 3-folds. One of them is related to a Hilbert modular surface,…
Node Query Preservation for Deterministic Linear Top-Down Tree Transducers
Kazuki Miyahara, Kenji Hashimoto, Hiroyuki Seki
This paper discusses the decidability of node query preservation problems for XML document transformations. We assume a transformation given by a deterministic linear top-down data…
XPath Satisfiability with Parent Axes or Qualifiers Is Tractable under Many of Real-World DTDs
Yasunori Ishihara, Nobutaka Suzuki, Kenji Hashimoto +2
This paper aims at finding a subclass of DTDs that covers many of the real-world DTDs while offering a polynomial-time complexity for deciding the XPath satisfiability problem. In…
Lepton Flavor Model and Decaying Dark Matter in The Binary Icosahedral Group Symmetry
Kenji Hashimoto, Hiroshi Okada
We propose a new flavor model that can simlutaneously well-describe the indirect detection experiment of (decaying) dark matter in the cosmic-ray, with the binary icosahedral group…
Finite Symplectic Actions on the K3 Lattice
Kenji Hashimoto
In this paper, we study finite symplectic actions on K3 surfaces X, i.e. actions of finite groups G on X which act on H^{2,0}(X) trivially. We show that the action on the K3 lattic…
Period map of a certain K3 family with an S5-action
Kenji Hashimoto, Tomohide Terasoma
In this paper, we study the period map of a certain one-parameter family of quartic K3 surfaces with an S5-action. We construct automorphic forms on the period domain as the pull-b…