Displaying similar documents to “Geometric subgroups of surface braid groups”

Fibred closed braids with disc-band fibre surfaces

Marta Rampichini (2004)

Bollettino dell'Unione Matematica Italiana

Similarity:

A classical result by Stallings provides a necessary and sufficient condition to decide whether a given embedded surface S is a fibre in S 3 - ∂ ⁡ S . In this paper it is described how to find a candidate fibre surface for a a link presented as a closed braid. Also it is described an implemented algorithm to find the main ingredients of the necessary and sufficient condition of Stallings, namely presentations of the fundamental groups of the surface and of its complement in S 3 , and an explicit expression...

On generalized M * - groups.

Ikikardes, Sebahattin, Sahin, Recep (2010)

Analele Ştiinţifice ale Universităţii “Ovidius" Constanţa. Seria: Matematică

Similarity:

On small distances of small 2-groups

Natalia Zhukavets (2001)

Commentationes Mathematicae Universitatis Carolinae

Similarity:

The paper reports the results of a search for pairs of groups of order n that can be placed in the distance n 2 / 4 for the case when n ∈ { 16 , 32 } . The constructions that are used are of the general character and some of their properties are discussed as well.

Dehn twists on nonorientable surfaces

Michał Stukow (2006)

Fundamenta Mathematicae

Similarity:

Let t a be the Dehn twist about a circle a on an orientable surface. It is well known that for each circle b and an integer n, I ( t ⁿ a ( b ) , b ) = | n | I ( a , b ) ² , where I(·,·) is the geometric intersection number. We prove a similar formula for circles on nonorientable surfaces. As a corollary we prove some algebraic properties of twists on nonorientable surfaces. We also prove that if ℳ(N) is the mapping class group of a nonorientable surface N, then up to a finite number of exceptions, the centraliser of the subgroup...

Waldhausen’s Nil groups and continuously controlled K-theory

Hans Munkholm, Stratos Prassidis (1999)

Fundamenta Mathematicae

Similarity:

Let Γ = Γ 1 * G Γ 2 be the pushout of two groups Γ i , i = 1,2, over a common subgroup G, and H be the double mapping cylinder of the corresponding diagram of classifying spaces B Γ 1 ← B G ← B Γ 2 . Denote by ξ the diagram I p ← H 1 → X = H , where p is the natural map onto the unit interval. We show that the N i l ∼ groups which occur in Waldhausen’s description of K * ( ℤ Γ ) coincide with the continuously controlled groups * c c ( ξ ) , defined by Anderson and Munkholm. This also allows us to identify the continuously controlled groups * c c ( ξ + ) which are known to form...

Malnormal subgroups and Frobenius groups: basics and examples

Pierre de la Harpe, Claude Weber (2014)

Confluentes Mathematici

Similarity:

Malnormal subgroups occur in various contexts. We review a large number of examples, and compare the general situation to that of finite Frobenius groups of permutations. In a companion paper [18], we analyse when peripheral subgroups of knot groups and 3 -manifold groups are malnormal.