Displaying similar documents to “On the Frouxe-Rabinovitch series for free groups”

Free and non-free subgroups of the fundamental group of the Hawaiian Earrings

Andreas Zastrow (2003)

Open Mathematics

Similarity:

The space which is composed by embedding countably many circles in such a way into the plane that their radii are given by a null-sequence and that they all have a common tangent point is called “The Hawaiian Earrings”. The fundamental group of this space is known to be a subgroup of the inverse limit of the finitely generated free groups, and it is known to be not free. Within the recent move of trying to get hands on the algebraic invariants of non-tame (e.g. non-triangulable) spaces...

A generator of morphisms for infinite words

Pascal Ochem (2006)

RAIRO - Theoretical Informatics and Applications

Similarity:

We present an algorithm which produces, in some cases, infinite words avoiding both large fractional repetitions and a given set of finite words. We use this method to show that all the ternary patterns whose avoidability index was left open in Cassaigne's thesis are 2-avoidable. We also prove that there exist exponentially many 7 4 + -free ternary words and 7 5 + -free 4-ary words. Finally we give small morphisms for binary words containing only the squares , 1 and (01)² and for binary words...