Virtually free
نویسندگان
چکیده
منابع مشابه
Virtually scaling-free adaptive CORDIC rotator
The authors propose a coordinate rotation digital computer (CORDIC) rotator algorithm that eliminates the problems of scale factor compensation and limited range of convergence associated with the classical CORDIC algorithm. In the proposed scheme, depending on the target angle or the initial coordinate of the vector, a scaling by 1 or 1= p 2 is needed that can be realised with minimal hardware...
متن کاملA Characterisation of Virtually Free Groups
We prove that a finitely generated group G is virtually free if and only if there exists a generating set for G and k > 0 such that all k-locally geodesic words with respect to that generating set are geodesic.
متن کاملFurstenberg Entropy Realizations for Virtually Free Groups and Lamplighter Groups
Let (G, μ) be a discrete group with a generating probability measure. Nevo shows that if G has property (T) then there exists an ε > 0 such that the Furstenberg entropy of any (G, μ)-stationary space is either zero or larger than ε. Virtually free groups, such as SL2(Z), do not have property (T). For these groups, we construct stationary actions with arbitrarily small, positive entropy. This co...
متن کاملThe Subgroup Growth Spectrum of Virtually Free Groups
For a finitely generated group Γ denote by μ(Γ) the growth coefficient of Γ, that is, the infimum over all real numbers d such that sn(Γ) < n!d. We show that the growth coefficient of a virtually free group is always rational, and that every rational number occurs as growth coefficient of some virtually free group. For a finitely generated group Γ denote by sn(Γ) the number of subgroups of inde...
متن کاملFinite automata for Schreier graphs of virtually free groups
The Stallings construction for f.g. subgroups of free groups is generalized by introducing the concept of Stallings section, which allows an efficient computation of the core of a Schreier graph based on edge folding. It is proved that those groups admitting Stallings sections are precisely f.g. virtually free groups, through a constructive approach based on Basse-Serre theory. Complexity issue...
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ژورنال
عنوان ژورنال: Index on Censorship
سال: 1996
ISSN: 0306-4220,1746-6067
DOI: 10.1177/030642209602500119