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Links between two semisymmetric graphs on 112 vertices via association schemes. (English) Zbl 1244.05235

Summary: This paper provides a model of the use of computer algebra experimentation in algebraic graph theory. Starting from the semisymmetric cubic graph \(\mathcal L\) on 112 vertices, we embed it into another semisymmetric graph \(\mathcal N\) of valency 15 on the same vertex set. In order to consider systematically the links between \(\mathcal L\) and \(\mathcal N\), a number of combinatorial structures are involved and related coherent configurations are investigated. In particular, the construction of the incidence double cover of directed graphs is exploited.
As a natural by-product of the approach presented here, a number of new interesting (mostly non-Schurian) association schemes on 56, 112 and 120 vertices are introduced and briefly discussed. We use computer algebra system GAP (including GRAPE and nauty), as well as computer package COCO.

MSC:

05E30 Association schemes, strongly regular graphs
05C60 Isomorphism problems in graph theory (reconstruction conjecture, etc.) and homomorphisms (subgraph embedding, etc.)
68W30 Symbolic computation and algebraic computation

Software:

nauty; GRAPE; GAP
Full Text: DOI

References:

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