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Yaroslav Shitov

Publications and source records attributed to Yaroslav Shitov.

43 records · Page 3Linked to original sources
arXiv2013

The complexity of tropical matrix factorization

The tropical arithmetic operations on $\mathbb{R}$ are defined by $a\oplus b=\min\{a,b\}$ and $a\otimes b=a+b$. Let $A$ be a tropical matrix and $k$ a positive integer, the problem of Tropical Matrix Factorization (TMF) asks whether there exist tropical matrices $B\in\mathbb{R}^{m\times k}$ and $C\in\mathbb{R}^{k\times n}$ satisfying $B\otimes C=A$. We show that no algorithm for TMF is likely to work in polynomial time for every fixed $k$, thus resolving a problem proposed by Barvinok in 1993.

math.CO↗
arXiv2013

An upper bound for nonnegative rank

We provide a nontrivial upper bound for the nonnegative rank of rank-three matrices, which allows us to prove that [6(n+1)/7] linear inequalities suffice to describe a convex n-gon up to a linear projection.

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arXiv2012

On matrices with different tropical and Kapranov ranks

In this note, we generalize the technique developed in [13] and prove that every 5xn matrix of tropical rank at most 3 has Kapranov rank at most 3, for the ground field that contains at least 4 elements. For the ground field either F_2 or F_3, we construct an example of a 5x5 matrix with tropical rank 3 and Kapranov rank 4.

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arXiv2012

Tropical matrices and group representations

The paper gives a complete description of the subgroups of the semigroup of tropical n-by-n matrices up to an isomorphism. In particular, we show that every of these groups has a torsion-free abelian subgroup of index at most n!, proving the conjecture of Johnson and Kambites.

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arXiv2011

When do the r-by-r minors of a matrix form a tropical basis?

We show that the r-by-r minors of a d-by-n matrix of variables form a tropical basis of the ideal they generate if and only if r<4, or r=min(d,n), or else r=4 and min(d,n)<7. This answers a question asked by M. Chan, A. Jensen, and E. Rubei.

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