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تسجيل مستخدم جديدIsomorphism classes of association schemes induced by Hadamard matrices
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Every Hadamard matrix $H$ of order $n > 1$ induces a graph with $4n$ vertices, called the Hadamard graph $Gamma(H)$ of $H$. Since $Gamma(H)$ is a distance-regular graph with diameter $4$, it induces a $4$-class association scheme $(Omega, S)$ of order $4n$. In this article we deal with fission schemes of $(Omega, S)$ under certain conditions, and for such a fission scheme we estimate the number of isomorphism classes with the same intersection numbers as the fission scheme.
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In this paper, we obtain a number of new infinite families of Hadamard matrices. Our constructions are based on four new constructions of difference families with four or eight blocks. By applying the Wallis-Whiteman array or the Kharaghani array to
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In this paper, we generalize classical constructions of skew Hadamard difference families with two or four blocks in the additive groups of finite fields given by Szekeres (1969, 1971), Whiteman (1971) and Wallis-Whiteman (1972). In particular, we sh
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Recent classification of $frac{3}{2}$-transitive permutation groups leaves us with three infinite families of groups which are neither $2$-transitive, nor Frobenius, nor one-dimensional affine. The groups of the first two families correspond to speci
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