2 research outputs found

    Matroids with no U2,nU_{2,n}-minor and many hyperplanes

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    We construct, for every rβ‰₯3r \ge 3 and every prime power q>10q > 10, a rank-rr matroid with no U2,q+2U_{2,q+2}-minor, having more hyperplanes than the rank-rr projective geometry over GF(q)\mathrm{GF}(q)

    The number of lines in a matroid with no U2,nU_{2,n}-minor

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    We show that, if qq is a prime power at most 5, then every rank-rr matroid with no U2,q+2U_{2,q+2}-minor has no more lines than a rank-rr projective geometry over GF(q)(q). We also give examples showing that for every other prime power this bound does not hold
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