10 citations · 31 across the 16 of their papers we have counts for
19 papers
Strong Lefschetz property of the Kirchhoff algebra of the complete tripartite graph
Yohji Akama
By Whitney's 2-isomorphism theorem, the cycle matroids of two graphs are isomorphic if and only if one graph can be transformed into the other by finitely many applications of two…
Asymptotic locations of bounded and unbounded eigenvalues of sample correlation matrices of certain factor models -- application to a components retention rule
Yohji Akama, Peng Tian
Let the dimension of data and the sample size tend to with . The spectral properties of a sample correlation matrix and a sample covari…
Correlation matrix of equi-correlated normal population: fluctuation of the largest eigenvalue, scaling of the bulk eigenvalues, and stock market
Yohji Akama
Given an -dimensional sample of size and form a sample correlation matrix . Suppose that and tend to infinity with converging to a fixed finite co…
A dichotomous behavior of Guttman-Kaiser criterion from equi-correlated normal population
Yohji Akama, Atina Husnaqilati
We consider a -dimensional, centered normal population such that all variables have a positive variance and any correlation coefficient between different variables is a gi…
Graphs on surfaces with positive Forman curvature or corner curvature
Yohji Akama, Bobo Hua, Yanhui Su +1
On one hand, we study the class of graphs on surfaces, satisfying tessellation properties, with positive Forman curvature on each edge. Via medial graphs, we provide a new proof fo…
A curvature notion for planar graphs stable under planar duality
Yohji Akama, Bobo Hua, Yanhui Su +1
Woess \cite{Woess98} introduced a curvature notion on the set of edges of a planar graph, called -curvature in our paper, which is stable under the planar duality. We study geom…
Classification of spherical tilings by congruent quadrangles over pseudo-double wheels (II)
Yohji Akama
We classify all edge-to-edge spherical isohedral 4-gonal tilings such that the skeletons are pseudo-double wheels. For this, we characterize these spherical tilings by a quadratic…
Hyperbolic polyhedral surfaces with regular faces
Yohji Akama, Bobo Hua
We study hyperbolic polyhedral surfaces with faces isometric to regular hyperbolic polygons satisfying that the total angles at vertices are at least The combinatorial inform…
Confluent terminating extensional lambda-calculi with surjective pairing and terminal type
Yohji Akama
For the lambda-calculus with surjective pairing and terminal type, Curien and Di Cosmo were inspired by Knuth-Bendix completion, and introduced a confluent rewriting system that (1…
Tilings of the Sphere by Congruent Pentagons III: Edge Combination
Yohji Akama, Erxiao Wang, Min Yan
There are exactly eight edge-to-edge tilings of the sphere by congruent equilateral pentagons: three pentagonal subdivision tilings with 12, 24, 60 tiles; four earth map tilings wi…
Areas of spherical polyhedral surfaces with regular faces
Yohji Akama, Bobo Hua, Yanhui Su
For a finite planar graph, it associates with some metric spaces, called (regular) spherical polyhedral surfaces, by replacing faces with regular spherical polygons in the unit sph…
On Deformed Dodecahedron Tiling
Yohji Akama, Min Yan
There is only one type of tilings of the sphere by congruent pentagons. These tilings are isohedral.
Spherical tilings by congruent quadrangles over pseudo-double wheels (III) - the essential uniqueness in case of convex tiles
Yohji Akama, Yudai Sakano
In [B.Gruenbaum, G.C. Shephard, Spherical tilings with transitivity properties, in: The geometric vein, Springer, New York, 1981, pp. 65-98], they proved "for every spherical norma…
Realizability Interpretation of PA by Iterated Limiting PCA
Yohji Akama
For any partial combinatory algebra (PCA for short) A, the class of A-representable partial functions from N to A quotiented by the filter of cofinite sets of N, is a PCA such that…
Classification of spherical tilings by congruent quadrangles over pseudo-double wheels (I) -- a special tiling by congruent concave quadrangles
Yohji Akama
Every simple quadrangulation of the sphere is generated by a graph called a pseudo-double wheel with two local expansions (Brinkmann et al. "Generation of simple quadrangulations o…
A new order theory of set systems and better quasi-orderings
Yohji Akama
By reformulating a learning process of a set system L as a game between Teacher (presenter of data) and Learner (updater of the abstract independent set), we define the order type…
VC dimension of ellipsoids
Yohji Akama, Kei Irie
We will establish that the VC dimension of the class of d-dimensional ellipsoids is (d^2+3d)/2, and that maximum likelihood estimate with N-component d-dimensional Gaussian mixture…
Random fields on model sets with localized dependency and their diffraction
Yohji Akama, Shinji Iizuka
For a random field on a general discrete set, we introduce a condition that the range of the correlation from each site is within a predefined compact set D. For such a random fiel…
Set systems: order types, continuous nondeterministic deformations, and quasi-orders
Yohji Akama
By reformulating a learning process of a set system L as a game between Teacher and Learner, we define the order type of L to be the order type of the game tree, if the tree is wel…