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Elena Kreines

Publications and source records attributed to Elena Kreines.

2 recordsLinked to original sources

Belyi pair for the orientation cover of $ \overline{{\mathcal M}_{0,5}^{\mathbb R}}$

Let $\overline{{\mathcal M}_{0,5}^{\mathbb R}}$ be the Deligne-Mumford compactification of the moduli space of genus 0 real algebraic curves with 5 marked points. By ${\mathcal L}(\overline{{\mathcal M}_{0,5}^{\mathbb R}})$ we denote its orientation cover. The cell decomposition of ${\mathcal L}(\overline{{\mathcal M}_{0,5}^{\mathbb R}})$ is a dessin d'enfant of the genus 4. In this paper we compute the Belyi pair for this dessin. In particular, it appears that the corresponding curve is a celebrated Bring curve.

math.AG

Integrability of matrices

The concepts of differentiation and integration for matrices are known. As far as each matrix is differentiable, it is not clear a priori whether a given matrix is integrable or not. Recently some progress was obtained for diagonalizable matrices, however general problem remained open. In this paper, we present a full solution of the integrability problem. Namely, we provide necessary and sufficient conditions for a given matrix to be integrable in terms of its characteristic polynomial. Furthermore, we find necessary and sufficient conditions for the existence of integrable and non-integrable matrices with given geometric multiplicities of eigenvalues. Our approach relies on properties of some special classes of polynomials, namely, Shabat polynomials and conservative polynomials, arising in number theory and dynamics.

math.CO