1. The invariant of PGU(3,q) in the Hermitian function fieldBarbara Gatti, Francesco Ghiandoni, Gábor Korchmáros, 2025, original scientific article Abstract: Let F = F|K be a function field over an algebraically closed constant field K of positive characteristic p. For a K-automorphism group G of F, the invariant of G is the fixed field FG of G. If F has transendency degree 1 (i.e. F is the function field of an irreducible curve) and FG is rational, then each generator of FG uniquely determines FG and it makes sense to call each of them the invariant of G. In this paper, F is the Hermitian function field K(Hq)=K(x,y) with yq + y − xq + 1 = 0 and q = pr. We determine the invariant of Aut(K(Hq)) \cong PGU(3,q), and discuss some related questions on Galois subcovers of maximal curves over finite fields.
Keywords: function field, finite field, automorphism group, invariant
Published in RUP: 21.10.2025; Views: 707; Downloads: 8
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4. Adjacency preservers, symmetric matrices, and coresMarko Orel, 2012, original scientific article Abstract: It is shown that the graph ▫$\Gamma_n$▫ that has the set of all ▫$n \times n$▫ symmetric matrices over a finite field as the vertex set, with two matrices being adjacent if and only if the rank of their difference equals one, is a core if ▫$n \ge 3$▫. Eigenvalues of the graph ▫$\Gamma_n$▫ are calculated as well.
Keywords: adjacency preserver, symmetric matrix, finite field, eigenvalue of a graph, coloring, quadratic form
Published in RUP: 15.10.2013; Views: 6438; Downloads: 152
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5. Coding theory and applications, solved exercises and problems of cyclic codesEnes Pašalić, 2013, other educational material Keywords: finite field, counting cyclic codes, codeword, Hamming code, Ternary Golay code, BCH code, BCH decoding, Fire code, Erasure corrections, MDS code, convolutional code
Published in RUP: 15.10.2013; Views: 4914; Downloads: 101
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