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Representations of a free group of rank two by time-varying Mealy automata

Adam Woryna (2005)

Discussiones Mathematicae - General Algebra and Applications

In the group theory various representations of free groups are used. A representation of a free group of rank two by the so-calledtime-varying Mealy automata over the changing alphabet is given. Two different constructions of such automata are presented.

Representations of PGL ( 2 ) of a local field and harmonic cochains on graph

Paul Broussous (2009)

Annales de la faculté des sciences de Toulouse Mathématiques

We give combinatorial models for non-spherical, generic, smooth, complex representations of the group G = PGL ( 2 , F ) , where F is a non-Archimedean locally compact field. More precisely we carry on studying the graphs ( X ˜ k ) k 0 defined in a previous work. We show that such representations may be obtained as quotients of the cohomology of a graph X ˜ k , for a suitable integer k , or equivalently as subspaces of the space of discrete harmonic cochains on such a graph. Moreover, for supercuspidal representations, these models...

Réseaux de Coxeter-Davis et commensurateurs

Frédéric Haglund (1998)

Annales de l'institut Fourier

For each integer k 6 and each finite graph L , we construct a Coxeter group W and a non positively curved polygonal complex A on which W acts properly cocompactly, such that each polygon of A has k edges, and the link of each vertex of A is isomorphic to L . If L is a “generalized m -gon”, then A is a Tits building modelled on a reflection group of the hyperbolic plane. We give a condition on Aut ( L ) for Aut ( A ) to be non enumerable (which is satisfied if L is a thick classical generalized m -gon). On the other hand,...

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