Published in Mathematical Notes
The forms of the Segre cubic over non-algebraically closed fields, their automorphisms groups, and equivariant birational rigidity are studied. In particular, it is shown that all forms of the Segre cubic over any field have a point and are cubic hypersurfaces.
The Kawamata-Morrison cone conjecture have attracted a lot of attention in algebraic geometry. In this thesis, the author will deal with this conjecture for Calabi-Yau 3-folds whose nef cone is polyhedral in chapter 3. In chapter 4, we will investigate the null cone and the automorphism group of Calabi-Yau 3-folds of Picard number $4$, which serves...
The automorphism group of Hrushovski's pseudoplane associated to 5/8 is a simple group.
Published in Indian Journal of Pure and Applied Mathematics
A graph is symmetric if its automorphism group is transitive on the arc set of the graph. In this paper, we give a complete classification of connected pentavalent symmetric graphs of order 18p, for each prime p. It is shown that, such graphs there exist if and only if p = 2, 7 or 19, and up to isomorphism, there are only four such graphs.
Published in Proceedings of the Steklov Institute of Mathematics
The present paper is devoted to the further development of the discrete theory of Riemann surfaces, which was started in the papers by M. Baker and S. Norine and their followers at the beginning of the century. This theory considers finite graphs as analogs of Riemann surfaces and branched coverings of graphs as holomorphic mappings. The genus of a...
Published in Journal of Mathematical Sciences
A family A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathcal{A} $$\end{document} of non-empty subsets of a set X is called an upfamily, if, for each set A∈A\docu...
Published in European Journal of Mathematics
It is known that the moduli space of smooth Fano–Mukai fourfolds V18\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$V_{18}$$\end{document} of genus 10 has dimension one...
Published in Lobachevskii Journal of Mathematics
For a complete Cartan foliation (M,F) we introduce two algebraic invariants g0(M,F) and g1(M,F) which we call structure Lie algebras. If the transverse Cartan geometry of (M,F) is effective then g0(M,F) = g1(M,F). Weprove that if g0(M,F) is zero then in the category of Cartan foliations the group of all basic automorphisms of the foliation (M,F) ad...
The existence of an extremal self-dual binary linear code of length 120 is a long-standing open problem. We continue the investigation of its automorphism group, proving that automorphisms of order 30 and 57 cannot occur. Supposing the involutions acting fixed point freely, we show that also automorphisms of order 8 cannot occur and the automorphis...
Published in Japanese Journal of Mathematics
We discuss various results on Hilbert schemes of lines and conics and automorphism groups of smooth Fano threefolds of Picard rank 1. Besides a general review of facts well known to experts, the paper contains some new results, for instance, we give a description of the Hilbert scheme of conics on any smooth Fano threefold of index 1 and genus 10. ...
