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  • The search for small association schemes with noncyclotomic eigenvalues
    Herman, Allen ; Maleki, Roghayeh
    In this article we determine feasible parameter sets for (what could potentially be) commutative association schemes with noncyclotomic eigenvalues that are of smallest possible rank and order. A ... feasible parameter set for a commutative association scheme corresponds to a standard integral table algebra with integral multiplicities that satisfies all of the parameter restrictions known to hold for association schemes. For each rank and involution type, we generate an algebraic set for which any suitable integral solution corresponds to a standard integral table algebra with integral multiplicities, and then try to find the smallest suitable solution. The main results of this paper show the eigenvalues of association schemes of rank 4 and nonsymmetric association schemes of rank 5 will always be cyclotomic. In the rank 5 cases, the results rely on calculations done by computer for Grobner ¨ bases or for bases of rational vector spaces spanned by polynomials. We give several examples of feasible parameter sets for small symmetric association schemes of rank 5 that have noncyclotomic eigenvalues.
    Source: Ars mathematica contemporanea. - ISSN 1855-3966 (Vol. 23, iss. 3, 2023, str. 1-24)
    Type of material - article, component part ; adult, serious
    Publish date - 2023
    Language - english
    COBISS.SI-ID - 129103107

source: Ars mathematica contemporanea. - ISSN 1855-3966 (Vol. 23, iss. 3, 2023, str. 1-24)

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