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    Some design theoretic results on the Conway group ·0

    Fairbairn, Ben (2010) Some design theoretic results on the Conway group ·0. Electronic Journal of Combinatorics 17 (R18), pp. 1-11. ISSN 1077-8926.

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    Let Om be a set of 24 points with the structure of the (5,8,24) Steiner system, S, defined on it. The automorphism group of S acts on the famous Leech lattice, as does the binary Golay code defined by S. Let A,B ⊂ L be subsets of size four (“tetrads”). The structure of S forces each tetrad to define a certain partition of into six tetrads called a sextet. For each tetrad Conway defined a certain automorphism of the Leech lattice that extends the group generated by the above to the full automorphism group of the lattice. For the tetrad A he denoted this automorphism ZA. It is well known that for ZA and ZB to commute it is sufficient to have A and B belong to the same sextet. We extend this to a much less obvious necessary and sufficient condition, namely ZA and ZB will commute if and only if A∪B is contained in a block of S. We go on to extend this result to similar conditions for other elements of the group and show how neatly these results restrict to certain important subgroups.


    Item Type: Article
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Computing and Mathematical Sciences
    Depositing User: Ben Fairbairn
    Date Deposited: 20 Dec 2012 13:33
    Last Modified: 09 Aug 2023 12:32


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