74,311 research outputs found
Group actions and coverings of Brauer graph algebras
We develop a theory of group actions and coverings on Brauer graphs that
parallels the theory of group actions and coverings of algebras. In particular,
we show that any Brauer graph can be covered by a tower of coverings of Brauer
graphs such that the topmost covering has multiplicity function identically
one, no loops, and no multiple edges. Furthermore, we classify the coverings of
Brauer graph algebras that are again Brauer graph algebras.Comment: 26 pages Correction to statement of Theorem 6.7; a tower of coverings
has been introduce
Computation of highly ramified coverings
An almost Belyi covering is an algebraic covering of the projective line,
such that all ramified points except one simple ramified point lie above a set
of 3 points of the projective line. In general, there are 1-dimensional
families of these coverings with a fixed ramification pattern. (That is,
Hurwitz spaces for these coverings are curves.) In this paper, three almost
Belyi coverings of degrees 11, 12, and 20 are explicitly constructed. We
demonstrate how these coverings can be used for computation of several
algebraic solutions of the sixth Painleve equation.Comment: 26 page
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