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Coxeter group actions on the complement of hyperplanes and special involutions

Giovanni Felder, A. Veselov (2005)

Journal of the European Mathematical Society

We consider both standard and twisted actions of a (real) Coxeter group G on the complement G to the complexified reflection hyperplanes by combining the reflections with complex conjugation. We introduce a natural geometric class of special involutions in G and give explicit formulae which describe both actions on the total cohomology H * ( G , 𝒞 ) in terms of these involutions. As a corollary we prove that the corresponding twisted representation is regular only for the symmetric group S n , the Weyl groups...

Curvature and Flow in Digital Space

Atsushi Imiya (2013)

Actes des rencontres du CIRM

We first define the curvature indices of vertices of digital objects. Second, using these indices, we define the principal normal vectors of digital curves and surfaces. These definitions allow us to derive the Gauss-Bonnet theorem for digital objects. Third, we introduce curvature flow for isothetic polytopes defined in a digital space.

Curvature flows of maximal integral triangulations

Roland Bacher (1999)

Annales de l'institut Fourier

This paper describes local configurations of some planar triangulations. A Gauss-Bonnet-like formula holds locally for a kind of discrete “curvature” associated to such triangulations.

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