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Displaying 881 – 900 of 1792

Plane curves and their fundamental groups: Generalizations of Uludağ's construction.

Garber, David (2003)

Algebraic & Geometric Topology

Platonic triangles of groups.

Alperin, Roger C. (1998)

Experimental Mathematics

P-nilpotent completion is not idempotent.

Geok Choo Tan (1997)

Publicacions Matemàtiques

Let P be an arbitrary set of primes. The P-nilpotent completion of a group G is defined by the group homomorphism η: G → GP' where GP' = inv lim(G/ΓiG)P. Here Γ2G is the commutator subgroup [G,G] and ΓiG the subgroup [G, Γi−1G] when i > 2. In this paper, we prove that P-nilpotent completion of an infinitely generated free group F does not induce an isomorphism on the first homology group with ZP coefficients. Hence, P-nilpotent completion is not idempotent. Another important consequence of...

Poincaré duality groups of dimension two.

Beno Eckmann, Heinz Müller (1980)

Commentarii mathematici Helvetici

Points fixes des automorphismes de groupe hyperbolique

Frédéric Paulin (1989)

Annales de l'institut Fourier

Nous montrons que le sous-groupe des points fixes d’un automorphisme d’un groupe hyperbolique au sens de M. Gromov est de type fini.

Polycyclic groups with automorphisms of order four

Tao Xu, Fang Zhou, Heguo Liu (2016)

Czechoslovak Mathematical Journal

In this paper, we study the structure of polycyclic groups admitting an automorphism of order four on the basis of Neumann’s result, and prove that if $α$ is an automorphism of order four of a polycyclic group $G$ and the map $ϕ : G \to G$ defined by $g^{ϕ} = [g, α]$ is surjective, then $G$ contains a characteristic subgroup $H$ of finite index such that the second derived subgroup $H^{''}$ is included in the centre of $H$ and $C_{H} (α^{2})$ is abelian, both $C_{G} (α^{2})$ and $G / [G, α^{2}]$ are abelian-by-finite. These results extend recent and classical results in the literature....

Polyèdres finis de dimension 2 à courbure $\leq 0$ et de rang 2

Sylvain Barré (1995)

Annales de l'institut Fourier

On définit localement la notion de polyèdre de rang deux pour un polyèdre fini de dimension deux à courbure négative ou nulle. On montre que le revêtement universel d’un tel espace est soit le produit de deux arbres, soit un immeuble de Tits euclidien de rang deux.