Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Four-class Skew-symmetric Association Schemes   An association scheme is called skew-symmetric if it has no symmetric
adjacency relations other than the diagonal one. In this paper, we study
4-class skew-symmetric association schemes. In J. Ma [On the nonexistence of
skew-symmetric amorphous association schemes, submitted for publication], we
discovered that their character tables fall into three types. We now determine
their intersection matrices. We then determine the character tables and
intersection numbers for 4-class skew-symmetric pseudocyclic association
schemes, the only known examples of which are cyclotomic schemes. As a result,
we answer a question raised by S. Y. Song [Commutative association schemes
whose symmetrizations have two classes, J. Algebraic Combin. 5(1) 47-55, 1996].
We characterize and classify 4-class imprimitive skew-symmetric association
schemes. We also prove that no 2-class Johnson scheme can admit a 4-class
skew-symmetric fission scheme. Based on three types of character tables above,
a short list of feasible parameters is generated.

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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio