Amenability and computability

In this paper we extend the approach of M. Cavaleri to effective amenability to the class of computably enumerable groups, i.e. in particular we do not assume that groups are finitely generated. In the case of computable groups we also study complexity of the set of all effective F{\o}lner sequences and effective paradoxical decomposition. The paper is extended by an appendix written by Aleksander Ivanov, which contains a solution of a problem from the previous version

Łódź Leisure Time Space as Perceived by Liceum Students and Members of the ‘Universities of the Third Age’

The article is a summary of research into the perception of leisure time space, conducted in 2014 among Liceum students (aged 16-19) and members of the ‘Universities of the Third Age’ (U3A) in Łódź. The author compared perceptions of the idea of leisure time by both of these groups, studied how they spent it and described the factors which have a significant influence. Next, he analysed different approaches to the urban space of Łódź as well as comparing them to the spatial range and the types of visited places and events