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JOURNALS // Trudy Instituta Matematiki i Mekhaniki UrO RAN // Archive

Trudy Inst. Mat. i Mekh. UrO RAN, 2017 Volume 23, Number 4, Pages 192–211 (Mi timm1479)

Symmetrical $2$-extensions of the $2$-dimensional grid. II

E. A. Konoval'chikab, K. V. Kostousova

a Krasovskii Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, 620990 Russia
b Nosov Magnitogorsk State Technical University, Magnitogorsk, 455000 Russia

Abstract: The investigation of symmetrical $q$-extensions of a $d$-dimensional cubic grid $\Lambda^{d}$ is of interest both for group theory and for graph theory. For small $d\geq 1$ and $q>1$ (especially for $q=2$), symmetrical $q$-extensions of $\Lambda^{d}$ are of interest for molecular crystallography and some phisycal theories. Earlier V. Trofimov proved that there are only finitely many symmetrical $2$-extensions of $\Lambda^{d}$ for any positive integer $d$. This paper is the second and concluding part of our work devoted to the description of all, up to equivalence, realizations of symmetrical $2$-extensions of $\Lambda^{2}$ (we show that there are $162$ such realizations). In the first part of our work, which was published earlier, we found all, up to equivalence, realizations of symmetrical $2$-extensions of $\Lambda^{2}$ such that only the trivial automorphism fixes all blocks of the imprimitivity system ($87$ realizations). In the present paper, we find the remaining realizations of symmetrical $2$-extensions of $\Lambda^{2}$.

Keywords: symmetrical extension of a graph, $d$-dimensional grid.

UDC: 512.54 +519.17

MSC: 05C25

Received: 12.01.2017

DOI: 10.21538/0134-4889-2017-23-4-192-211



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