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Naoya Yamaguchi

Publications and source records attributed to Naoya Yamaguchi.

At least 19 recordsLinked to original sources
arXiv2026

Principal Specialization of Monomial Symmetric Polynomials and Group Determinants of Cyclic Groups

In this paper, we study the principal specialization of monomial symmetric polynomials and investigate the special values of these polynomials at \[ ζ_{(n,k)} := ( 1, ζ_n, ζ_n^2, \dots, ζ_n^{kn-1} ), \] where $ζ_n$ is a primitive $n$th root of unity. We give explicit formulas for several classes of special values. We also show that these special values naturally appear as the coefficients in the expansion of the $k$th power of the circulant determinant of order $n$ (the group determinant of the cyclic group of order $n$). These results extend Ore's formulas for the case $k = 1$. Furthermore, we determine the number of terms in the $k$th power of the group permanent of the cyclic group of order $n$. This extends Brualdi and Newman's result for $k = 1$.

math.RT↗
arXiv2026

Direct determination of layer anomalous Hall conductivity using uniaxial Wannier functions

We propose a method for computing layer anomalous Hall conductivity (LAHC) in real space by integrating the Fukui-Hatsugai-Suzuki method with hybrid Wannier functions localized along a single axis. To validate the method, we calculated the LAHC of axion-insulating MnBi$_2$Te$_4$ and confirmed the agreement between the sum of LAHC on the surface and the surface AHC previously reported. We further applied the method to antiferromagnetic Mn$_2$Bi$_2$Te$_5$ and examined the dependence on the magnetic structure of LAHC, identifying cases with and without axion insulating behavior. This layer-resolved analysis offers a powerful tool for studying topological transport in complex materials, including heterostructures, and may guide the design of future devices based on the anomalous Hall effect with precise layer control.

cond-mat.mtrl-sci↗
arXiv2026

Group Permanents of Abelian $p$-Groups and Young Diagrams

We study the number $\Nu(\Per(G_λ))$ of distinct monomials with nonzero coefficients in the group permanent of an abelian $p$-group $G_λ$ associated with a partition $λ$ of a positive integer $N$. First, we derive an explicit formula for $\Nu(\Per(G_λ))$ in terms of the partial column sums of the Young diagram of $λ$. Next, we show that the relative order of the values $\Nu(\Per(G_λ))$ is determined by a lexicographic comparison of the conjugate Young diagrams. Finally, we investigate congruence properties of $\Nu(\Per(G_λ))$ for abelian $p$-groups and establish a criterion involving Wolstenholme primes.

math.RT↗
arXiv2025

Direct observation of band structure modifications from monolayer WSe2 to Janus WSSe

Janus monolayer transition metal dichalcogenides (TMDs), created by post-growth substitution of the top chalcogen layer, represent a new direction for engineering 2D crystal properties. However, their rapid ambient degradation and the difficulty of obtaining large-area monolayer samples have limited the available experimental probes, leaving their detailed electronic structure near the Fermi level largely unexplored. In this work, by performing micro-focused angle-resolved photoemission spectroscopy (μ-ARPES) on an identical sample transformed from monolayer WSe2 to Janus WSSe via a H2 plasma-assisted chalcogen-exchange method, we reveal the evolution of its electronic band structure. We observe ARPES signature consistent with the Rashba-type spin splitting due to broken horizontal mirror symmetry, and a significant upward shift of the highest valence band at the Γ-point by approximately 160 meV. These direct observations clarify the key electronic modifications that govern the material's properties and provide a pathway for band engineering in Janus TMDs.

cond-mat.mtrl-sci↗
arXiv2025

Group Determinants and Invariant Rings

In the study of group determinants, Frobenius introduced certain partial differential operators. This paper presents several results concerning the invariant rings derived from these partial differential operators.

math.RT↗
arXiv2024

Design of a Five-Fingered Hand with Full-Fingered Tactile Sensors Using Conductive Filaments and Its Application to Bending after Insertion Motion

The purpose of this study is to construct a contact point estimation system for the both side of a finger, and to realize a motion of bending the finger after inserting the finger into a tool (hereinafter referred to as the bending after insertion motion). In order to know the contact points of the full finger including the joints, we propose to fabricate a nerve inclusion flexible epidermis by combining a flexible epidermis and a nerve line made of conductive filaments, and estimate the contact position from the change of resistance of the nerve line. A nerve inclusion flexible epidermis attached to a thin fingered robotic hand was combined with a twin-armed robot and tool use experiments were conducted. The contact information can be used for tool use, confirming the effectiveness of the proposed method.

cs.RO↗
arXiv2024

A Robot Kinematics Model Estimation Using Inertial Sensors for On-Site Building Robotics

In order to make robots more useful in a variety of environments, they need to be highly portable so that they can be transported to wherever they are needed, and highly storable so that they can be stored when not in use. We propose "on-site robotics", which uses parts procured at the location where the robot will be active, and propose a new solution to the problem of portability and storability. In this paper, as a proof of concept for on-site robotics, we describe a method for estimating the kinematic model of a robot by using inertial measurement units (IMU) sensor module on rigid links, estimating the relative orientation between modules from angular velocity, and estimating the relative position from the measurement of centrifugal force. At the end of this paper, as an evaluation for this method, we present an experiment in which a robot made up of wooden sticks reaches a target position. In this experiment, even if the combination of the links is changed, the robot is able to reach the target position again immediately after estimation, showing that it can operate even after being reassembled. Our implementation is available on https://github.com/hiroya1224/urdf_estimation_with_imus .

cs.RO↗
arXiv2023

Thermoelectric effect in kagome lattice enhanced at van Hove singularities

We have performed first-principles calculations using density functional theory on a kagome lattice model with a chiral spin state, as a representative example demonstrating significant longitudinal and transverse thermoelectric properties. The results revealed that the saddle-point-type van Hove singularity (VHS) enhances thermoelectric effects. The longitudinal thermoelectric conductivity $α_{xx}$ was large at the chemical potentials tuned close to the band at the symmetry points, K (lower band edge), $Γ$ (upper band edge), and M (saddle point), where the VHSs of the density of states (DOS) were at the corresponding band energies. The transverse thermoelectric conductivity $α_{xy}$ was large at the chemical potential of saddle-point-type VHS. A large anomalous Nernst coefficient of about 10 $μ$V/K at 50 K was expected.

cond-mat.mtrl-sci↗
arXiv2023

Wolstenholme primes and group determinants of cyclic groups

A Wolstenholme prime is a prime number $p \geq 5$ that divides the numerator of the Bernoulli number $B_{p-3}$. A number of equivalent definitions for Wolstenholme primes are known, mostly related to congruences of harmonic sums or binomial coefficients. In this paper, we introduce an equivalent definition of Wolstelholme primes related the number of terms in the group determinant of cyclic groups, and equivalently, the cardinality of certain sets of restricted partitions.

math.NT↗
arXiv2023

A necessary and sufficient condition for a prime to be an integer group determinant of certain $p$-groups

We give a necessary and sufficient condition for a prime to be an integer group determinant for an arbitrary abelian $p$-group of the form ${\rm C}_{p} \times H$, where ${\rm C}_{p}$ is the cyclic group of order $p$. Also, we show that under certain conditions, the integer group determinant of a finite group $G$ that is prime is the integer group determinant of the abelianization of $G$. As a result, we know that the integer group determinant of a $p$-group that is prime is the integer group determinant of its abelianization.

math.NT↗
arXiv2023

Semantic Scene Difference Detection in Daily Life Patroling by Mobile Robots using Pre-Trained Large-Scale Vision-Language Model

It is important for daily life support robots to detect changes in their environment and perform tasks. In the field of anomaly detection in computer vision, probabilistic and deep learning methods have been used to calculate the image distance. These methods calculate distances by focusing on image pixels. In contrast, this study aims to detect semantic changes in the daily life environment using the current development of large-scale vision-language models. Using its Visual Question Answering (VQA) model, we propose a method to detect semantic changes by applying multiple questions to a reference image and a current image and obtaining answers in the form of sentences. Unlike deep learning-based methods in anomaly detection, this method does not require any training or fine-tuning, is not affected by noise, and is sensitive to semantic state changes in the real world. In our experiments, we demonstrated the effectiveness of this method by applying it to a patrol task in a real-life environment using a mobile robot, Fetch Mobile Manipulator. In the future, it may be possible to add explanatory power to changes in the daily life environment through spoken language.

cs.RO↗
arXiv2023

Inequality for the variance of an asymmetric loss

We assume that the forecast error follows a probability distribution which is symmetric and monotonically non-increasing on non-negative real numbers, and if there is a mismatch between observed and predicted value, then we suffer a loss. Under the assumptions, we solve a minimization problem with an asymmetric loss function. In addition, we give an inequality for the variance of the loss.

math.ST↗
arXiv2023

Generalized Dedekind's theorem and its application to integer group determinants

In this paper, we give a refinement of a generalized Dedekind's theorem. In addition, we show that all possible values of integer group determinants of any group are also possible values of integer group determinants of its any abelian subgroup. By applying the refinement of a generalized Dedekind's theorem, we determine all possible values of integer group determinants of the direct product group of the cyclic group of order $8$ and the cyclic group of order $2$.

math.RT↗
arXiv2023

Integer group determinants for abelian groups of order 16

For any positive integer $n$, let ${\rm C}_{n}$ be the cyclic group of order $n$. We determine all possible values of the integer group determinant of ${\rm C}_{4} \times {\rm C}_{2}^{2}$, which is the only unsolved abelian group of order $16$.

math.NT↗