Abstract
For an integer \(n\ge 2\), the triangular graph has vertex set the 2-subsets of \(\{1,\ldots ,n\}\) and edge set the pairs of 2-subsets intersecting at one point. Such graphs are known to be halved graphs of bipartite rectagraphs, which are connected triangle-free graphs in which every 2-path lies in a unique quadrangle. We refine this result and provide a characterisation of connected locally triangular graphs as halved graphs of normal quotients of n-cubes. To do so, we study a parameter that generalises the concept of minimum distance for a binary linear code to arbitrary automorphism groups of the n-cube.
This is a preview of subscription content, access via your institution.
References
Bamberg, J., Devillers, A., Fawcett, J.B., Praeger, C.E.: Locally triangular graphs and rectagraphs with symmetry. J. Comb. Theory Ser. A 133, 1–28 (2015)
Bosma, W., Cannon, J., Playoust, C.: The Magma algebra system. I. The user language. J. Symb. Comput. 24, 235–265 (1997)
Brouwer, A.E.: Classification of small \((0,2)\)-graphs. J. Comb. Theory Ser. A 113, 1636–1645 (2006)
Brouwer, A.E., Cohen, A.M., Neumaier, A.: Distance-Regular Graphs. Springer, Berlin (1989)
Jurišić, A., Koolen, J.: 1-homogeneous graphs with cocktail party \(\mu \)-graphs. J. Algebraic Comb. 18, 79–98 (2003)
Makhnev, A.A.: On the graphs with \(\mu \)-subgraphs isomorphic to \(K_{u\times 2}\). Proc. Steklov Inst. Math. Suppl. 2, S169–S178 (2001). Translated from Trudy Instituta Matematiki UrO RAN, Vol.7, No. 2 (2001)
Matsumoto, M.: On the classification of locally Hamming distance-regular graphs. RIMS Kôkyûroku 768, 50–61 (1991). http://www.kurims.kyoto-u.ac.jp/kyodo/kokyuroku/contents/pdf/0768-07.pdf
Neumaier, A.: Rectagraphs, diagrams, and Suzuki’s sporadic simple group. Ann. Discrete Math. 15, 305–318 (1982)
Perkel, M.: On Finite Groups Acting on Polygonal Graphs. Ph.D. thesis, University of Michigan (1977)
Author information
Authors and Affiliations
Corresponding author
Additional information
The author was supported by the Australian Research Council Discovery Project Grant DP130100106 and thanks the referees for helpful observations.
Rights and permissions
About this article
Cite this article
Fawcett, J.B. Locally triangular graphs and normal quotients of the n-cube. J Algebr Comb 44, 119–130 (2016). https://doi.org/10.1007/s10801-015-0659-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10801-015-0659-1