20,710 research outputs found
Groups generated by two elliptic elements in PU(2,1)
Let and be two elliptic elements in of order
and respectively, where . We prove that if the distance
between the complex lines or points fixed by and is large
than a certain number, then the group is discrete nonelementary and
isomorphic to the free product .Comment: 9 page
New Quantum Codes from Evaluation and Matrix-Product Codes
Stabilizer codes obtained via CSS code construction and Steane's enlargement
of subfield-subcodes and matrix-product codes coming from generalized
Reed-Muller, hyperbolic and affine variety codes are studied. Stabilizer codes
with good quantum parameters are supplied, in particular, some binary codes of
lengths 127 and 128 improve the parameters of the codes in
http://www.codetables.de. Moreover, non-binary codes are presented either with
parameters better than or equal to the quantum codes obtained from BCH codes by
La Guardia or with lengths that can not be reached by them
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