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pro vyhledávání: '"Rubei, Elena"'
Autor:
Rubei, Elena
Publikováno v:
The Electronic Journal of Linear Algebra, Vol. 40, 2024
The problem of finding the maximal dimension of linear or affine subspaces of matrices whose rank is constant, or bounded below, or bounded above, has attracted many mathematicians from the sixties to the present day. The problem has caught also the
Externí odkaz:
http://arxiv.org/abs/2405.04694
Autor:
Rubei, Elena
For every $n \in \mathbb{N}$ and every field $K$, let $N(n,K)$ be the set of the nilpotent $n \times n$ matrices over $K$ and let $D(n,K) $ be the set of the $n \times n$ matrices over $K$ which are diagonalizable over $K$. Moreover, let $R(n) $ be t
Externí odkaz:
http://arxiv.org/abs/2303.10629
Autor:
Rubei, Elena
Publikováno v:
Linear and Multilinear Algebra 72 (11), 1741-1750 (2024)
For every $n \in \mathbb{N}$ and every field $K$, let $A(n,K)$ be the vector space of the antisymmetric $(n \times n)$-matrices over $K$. We say that an affine subspace $S$ of $A(n,K)$ has constant rank $r$ if every matrix of $S$ has rank $r$. Define
Externí odkaz:
http://arxiv.org/abs/2209.07633
Autor:
Rubei, Elena
Publikováno v:
Linear Algebra and its Applications, 644, 259-269 (2022)
For every $m,n \in \mathbb{N}$ and every field $K$, let $M(m \times n, K)$ be the vector space of the $(m \times n)$-matrices over $K$ and let $S(n,K)$ be the vector space of the symmetric $(n \times n)$-matrices over $K$. We say that an affine subsp
Externí odkaz:
http://arxiv.org/abs/2111.14997
Autor:
Rubei, Elena
Publikováno v:
Linear Algebra and its Applications 608, 299-321 (2021)
Let $\alpha $ be a $p \times q$ interval matrix with $p \geq q$ and with the endpoints of all its entries in the set of the rational numbers. We prove that, if $\alpha $ contains a rank-$r$ real matrix with $r \in \{2, q-2,q-1,q\}$, then it contains
Externí odkaz:
http://arxiv.org/abs/1911.05762
Autor:
Rubei, Elena, Ziani, Dario Villanis
Given a positive-weighted simple connected graph with $m$ vertices, labelled by the numbers $1,\ldots,m$, we can construct an $m \times m$ matrix whose entry $(i,j)$, for any $i,j\in\{1,\dots,m\}$, is the minimal weight of a path between $i$ and $j$,
Externí odkaz:
http://arxiv.org/abs/1901.00360
Akademický článek
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Autor:
Rubei, Elena
An interval matrix is a matrix whose entries are intervals in the set of real numbers. We generalize this concept, which has been broadly studied, to other fields. Precisely we define a rational interval matrix to be a matrix whose entries are interv
Externí odkaz:
http://arxiv.org/abs/1812.07386
Autor:
Rubei, Elena
Publikováno v:
Linear and Multilinear Algebra, 68 (5), 931-939, (2020)
A general closed interval matrix is a matrix whose entries are closed connected nonempty subsets of the set of the real numbers, while an interval matrix is defined to be a matrix whose entries are closed bounded nonempty intervals in the set of real
Externí odkaz:
http://arxiv.org/abs/1803.05433