Generalised Sifting in Black-Box Groups

Sophie Ambrose, M. Neunhoffer, Cheryl Praeger, C. Schneider

    Research output: Contribution to journalArticlepeer-review


    This paper presents a generalisation of the sifting procedure introduced originally by Sims for computation with finite permutation groups, and now used for many computational procedures for groups, such as membership testing and finding group orders. The new procedure is a Monte Carlo algorithm, and it is presented and analysed in the context of black-box groups. It is based on a chain of subsets instead of a subgroup chain. Two general versions of the procedure are worked out in detail, and applications are given for membership tests for several of the sporadic simple groups. The authors' major objective was that the procedures could be proved to be Monte Carlo algorithms, and the costs computed. In addition, they explicitly determined suitable subset chains for six of the sporadic groups, and then implemented the algorithms involving these chains in the GAP computational algebra system. It turns out that sample implementations perform well in practice. The implementations will be made available publicly in the form of a GAP package.
    Original languageEnglish
    Pages (from-to)217-250
    JournalLMS Journal of Computation and Mathematics
    Publication statusPublished - 2005


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