Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Supplementary difference sets with symmetry for Hadamard matrices   First we give an overview of the known supplementary difference sets (SDS)
(A_i), i=1..4, with parameters (n;k_i;d), where k_i=|A_i| and each A_i is
either symmetric or skew and k_1 + ... + k_4 = n + d. Five new Williamson
matrices over the elementary abelian groups of order 25, 27 and 49 are
constructed. New examples of skew Hadamard matrices of order 4n for n=47,61,127
are presented. The last of these is obtained from a (127,57,76)-difference
family that we have constructed. An old non-published example of G-matrices of
order 37 is also included.

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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
5
The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: stat