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Mitsuhiro Miyazaki

Publications and source records attributed to Mitsuhiro Miyazaki.

31 records · Page 2Linked to original sources
arXiv2012

Typical ranks of certain 3-tensors and absolutely full column rank tensors

In this paper, we study typical ranks of 3-tensors and show that there are plural typical ranks for m\times n\times p tensors over R in the following cases: (1) 3\leq m\leq ρ(n) and (m-1)(n-1)+1\leq p\leq (m-1)n, where ρ is the Hurwitz-Radon function, (2) m=3, n\equiv 3\pmod 4 and p=2n-1, (3) m=4, n\equiv 2\pmod 4, n\geq 6 and p=3n-2, (4) m=6, n\equiv 4\pmod 8, n\geq 12 and p=5n-4. (5) m=10, n\equiv 24\pmod{32} and p=9n-8.

math.RA↗
arXiv2012

Typical rank of $m\times n\times (m-1)n$ tensors with $3\leq m\leq n$ over the real number field

Tensor type data are used recently in various application fields, and then a typical rank is important. Let $3\leq m\leq n$. We study typical ranks of $m\times n\times (m-1)n$ tensors over the real number field. Let $ρ$ be the Hurwitz-Radon function defined as $ρ(n)=2^b+8c$ for nonnegative integers $a,b,c$ such that $n=(2a+1)2^{b+4c}$ and $0\leq b<4$. If $m \leq ρ(n)$, then the set of $m\times n\times (m-1)n$ tensors has two typical ranks $(m-1)n,(m-1)n+1$. In this paper, we show that the converse is also true: if $m > ρ(n)$, then the set of $m\times n\times (m-1)n$ tensors has only one typical rank $(m-1)n$.

math.RA↗
arXiv2010

Tests of Non-Equivalence among Absolutely Nonsingular Tensors through Geometric Invariants

4x4x3 absolutely nonsingular tensors are characterized by their determinant polynomial. Non-quivalence among absolutely nonsingular tensors with respect to a class of linear transformations, which do not chage the tensor rank,is studied. It is shown theoretically that affine geometric invariants of the constant surface of a determinant polynomial is useful to discriminate non-equivalence among absolutely nonsingular tensors. Also numerical caluculations are presented and these invariants are shown to be useful indeed. For the caluculation of invarinats by 20-spherical design is also commented. We showed that an algebraic problem in tensor data analysis can be attacked by an affine geometric method.

stat.OT↗
arXiv2010

Perfect type of n-tensors

In various application fields, tensor type data are used recently and then a typical rank is important. Although there may be more than one typical ranks over the real number field, a generic rank over the complex number field is the minimum number of them. The set of $n$-tensors of type $p_1\times p_2\times\cdots\times p_n$ is called perfect, if it has a typical rank $\max(p_1,\ldots,p_n)$. In this paper, we determine perfect types of $n$-tensor.

math.RA↗
arXiv2009

Tensor rank problem in statistical high-dimensional data and quantum information theory:their comparisons on the methods and the results

Quantum communication is concerned with the complexity of entanglement of a state and statistical data analysis is concerned with the complexity of a model. A common key word for both is "rank". In this paper we will show that both community is tracing the same target and that the methods used are slightly different. Two different methods, the range criterion method from quantum communication and the determinant polynomial method, are shown as an examples.

quant-ph↗
arXiv2008

About the maximal rank of 3-tensors over the real and the complex number field

High dimensional array data, tensor data, is becoming important in recent days. Then maximal rank of tensors is important in theory and applications. In this paper we consider the maximal rank of 3 tensors. It can be attacked from various viewpoints, however, we trace the method of Atkinson-Stephens(1979) and Atkinson-Lloyd(1980). They treated the problem in the complex field, and we will present various bounds over the real field by proving several lemmas and propositions, which is real counterparts of their results.

math.RA↗
arXiv2008

A simple estimation of the maximal rank of tensors with two slices by row and column operations, symmetrization and induction

The determination of the maximal ranks of a set of a given type of tensors is a basic problem both in theory and application. In statistical applications, the maximal rank is related to the number of necessary parameters to be built in a tensor model. Based on this classical theorem by Bosch we will show the tight bound for 2 x n x n tensors by simple row and column operations, symmetrization and mathematical induction, which has been given by several authors based on eigenvalue theories.

math.RA↗
arXiv2006

Behavior of local cohomology modules under polarization

Let $S=k[x_1,..., x_n]$ be a polynomial ring over a field $k$ with $n$ variables $x_1$, ..., $x_n$, $\mmmm$ the irrelevant maximal ideal of $S$, $I$ a monomial ideal in $S$ and $I'$ the polarization of $I$ in the polynomial ring $S'$ with $ρ$ variables. We show that each graded piece $H_\mmmm^i(S/I)_\aaa$, $\aaa\in\ZZZ^n$, of the local cohomology module $H_\mmmm^i(S/I)$ is isomorphic to a specific graded piece $H_{\mmmm'}^{i+ρ-n}(S'/I')_\alphaaa$, $\alphaaa\in\ZZZ^ρ$, of the local cohomology module $H_{\mmmm'}^{i+ρ-n}(S'/I')$, where $\mmmm'$ is the irrelevant maximal ideal of $S'$.

math.AC↗
arXiv2005

On the analytic spread and the reduction number of the ideal of maximal minors

Let $m$, $n$, $a_1$, ..., $a_r$, $b_1$, ..., $b_r$ be integers with $1\leq a_1<...<a_r\leq m$ and $1\leq b_1<...<b_r\leq n$. And let $x$ be the universal $m\times n$ matrix with the property that $i$-minors of first $a_i-1$ rows and first $b_i-1$ columns are all zero, for $i=1$, ..., $r+1$ ($a_{r+1}=m+1$ and $b_{r+1}=n+1$). For an integer $u$ with $1\leq u\leq m$, we denote by $U$ the $u\times n$ matrix consisting of the first $u$ rows of $x$. In this paper, we consider the analytic spread and the reduction number of the ideal of maximal minors of $U$

math.AC↗
arXiv2005

On the generating poset of Schubert cycles and the characterization of Gorenstein property

The homogeneous coordinate ring of a Schubert variety (a Schubert cycle for short) is an algebra with straightening law generated by a distributive lattice. This paper gives a simple method to study the set of all the join-irreducible elements of this distributive lattice, and gives a simple proof of the criterion of the Gorenstein property of Schubert cycles.

math.AC↗
arXiv2005

A sufficient condition for a Hibi ring to be level and levelness of Schubert cycles

Let $K$ be a field, $D$ a finite distributive lattice and $P$ the set of all join-irreducible elements of $D$. We show that if $\{y\in P\mid y\geq x\}$ is pure for any $x\in P$, then the Hibi ring $\RRRRR_K(D)$ is level. Using this result and the argument of sagbi basis theory, we show that the homogeneous coordinate rings of Schubert subvarieties of Grassmannians are level.

math.AC↗
arXiv2004

On the discrete counterparts of Cohen-Macaulay algebras with straightening laws

We study properties of a poset generating a Cohen-Macaulay algebra with straightening laws (ASL for short). We show that if a poset $P$ generates a Cohen-Macaulay ASL, then $P$ is pure and, if $P$ is moreover Buchsbaum, then $P$ is Cohen-Macaulay. Some results concerning a Rees algebra of an ASL defined by a straightening closed ideal are also established. And it is shown that if $P$ is a Cohen-Macaulay poset with unique minimal element and $Q$ is a poset ideal of $P$, then $P\uplus Q$ is also Cohen-Macaulay.

math.AC↗