Zobrazeno 1 - 10
of 119
pro vyhledávání: '"Siran, Jozef"'
Autor:
Reade, Olivia, Širáň, Jozef
With the help of the theory of holomorphic and anti-holomorphic differentials, G. A. Jones [Chiral covers of hypermaps, Ars Math. Contemp. 8 (2015), 425-431] proved that every regular hypermap of a non-spherical type is covered by an infinite number
Externí odkaz:
http://arxiv.org/abs/2402.14420
An embedding of a graph on an orientable surface is orientably-regular (or rotary, in an equivalent terminology) if the group of orientation-preserving automorphisms of the embedding is transitive (and hence regular) on incident vertex-edge pairs of
Externí odkaz:
http://arxiv.org/abs/2311.09666
We analyze graphs attaining the extreme values of various spectral indices in the class of all simple connected graphs, as well as in the class of graphs which are not complete multipartite graphs. We also present results on density of spectral gap i
Externí odkaz:
http://arxiv.org/abs/2306.06860
Publikováno v:
In Discrete Mathematics August 2024 347(8)
We begin the study of collections of three blocks which can occur in a symmetric configuration with block size 3, $v_3$. Formulae are derived for the number of occurrences of these and it is shown that the triangle, i.e. abf, ace, bcd is a basis. It
Externí odkaz:
http://arxiv.org/abs/2108.06795
Publikováno v:
In Discrete Mathematics May 2024 347(5)
Autor:
Jeans, Olivia, Širáň, Jozef
An edge-biregular map arises as a smooth normal quotient of a unique index-two subgroup of a full triangle group acting with two edge-orbits. We give a classification of all finite edge-biregular maps on surfaces of negative prime Euler characteristi
Externí odkaz:
http://arxiv.org/abs/2011.00322
Autor:
Pavlíková, Soňa, Širáň, Jozef
We determine character tables for twisted fractional linear groups that form the `other' family in Zassenhaus' classification of finite sharply 3-transitive groups.
Comment: 26 pages
Comment: 26 pages
Externí odkaz:
http://arxiv.org/abs/2009.12963
Publikováno v:
J. Combin. Des. (2021), 1--27
The study of symmetric configurations $v_3$ with block size 3 has a long and rich history. In this paper we consider two colouring problems which arise naturally in the study of these structures. The first of these is weak colouring, in which no bloc
Externí odkaz:
http://arxiv.org/abs/2004.04514
It is proved that for any prescribed orientation of the triples of either a Steiner triple system or a Latin square of odd order, there exists an embedding in an orientable surface with the triples forming triangular faces and one extra large face.
Externí odkaz:
http://arxiv.org/abs/1911.07664