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An application of principal bundles to coloring of graphs and hypergraphs

Milgram, James R., Zvengrowski, Peter (1994)

Proceedings of the Winter School "Geometry and Physics"

An interesting connection between the chromatic number of a graph G and the connectivity of an associated simplicial complex N ( G ) , its “neighborhood complex”, was found by Lovász in 1978 (cf. L. Lovász [J. Comb. Theory, Ser. A 25, 319-324 (1978; Zbl 0418.05028)]). In 1986 a generalization to the chromatic number of a k -uniform hypergraph H , for k an odd prime, using an associated simplicial complex C ( H ) , was found ([N. Alon, P. Frankl and L. Lovász, Trans. Am. Math. Soc. 298, 359-370 (1986; Zbl 0605.05033)],...

Characteristic classes for A -bundles

Cap, Andreas, Schichl, Hermann (1996)

Proceedings of the Winter School "Geometry and Physics"

The authors generalize a construction of Connes by defining for an A -bundle E over smooth manifold X and a reduced cyclic cohomology class c a sequence of de Rham cohomology classes c h c k ( E ) . Here A is a convenient algebra, defined by the authors, and E is a locally trivial bundle with standard fibre a right finitely generated projective A -module and bounded A -modules homomorphisms as transition functions.

Circular vectors and toroidal matrices

Znojil, M. (1996)

Proceedings of the Winter School "Geometry and Physics"

Summary: Arrays of numbers may be written not only on a line (= ``a vector'') or in the plain (= ``a matrix'') but also on a circle (= ``a circular vector''), on a torus (= ``a toroidal matrix'') etc. In the latter case, the immanent index-rotation ambiguity converts the standard ``scalar'' product into a binary operation with several interesting properties.

Clifford algebra with Reduce

Brackx, Freddy, Constales, Denis, Delanghe, Richard, Serras, Herman (1987)

Proceedings of the Winter School "Geometry and Physics"

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