Turku Centre for Computer Science

About: Turku Centre for Computer Science is a facility organization based out in Turku, Finland. It is known for research contribution in the topics: Decidability & Word (group theory). The organization has 382 authors who have published 1027 publications receiving 19560 citations.

On abelian versions of critical factorization theorem

Abstract: In the paper we study abelian versions of the critical factorization theorem. We investigate both similarities and differences between the abelian powers and the usual powers. The results we obtained show that the constraints for abelian powers implying periodicity should be quite strong, but still natural analogies exist.

Revenue Models of Application Developers in Android Market Ecosystem

Abstract: Mobile application ecosystems have growth rapidly in the past few years. Increasing number of startups and established developers are alike offering their products in different marketplaces such as Android Market and Apple App Store. In this paper, we are studying revenue models used in Android Market. For analysis, we gathered the data of 351,601 applications from their public pages at the marketplace. From these, a random sample of 100 applications was used in a qualitative study of revenue streams. The results indicate that a part of the marketplace can be explained with traditional models but free applications use complex revenue models. Basing on the qualitative analysis, we identified four general business strategy categories for further studies.

Safety Analysis in Formal Specification

Abstract: Formal methods give us techniques to specify the functionality of a system, to verify its correctness or to develop the system stepwise from an abstract specification to its implementation. These aspects are important when designing safety-critical systems. Safety analysis is a vital part of the development of such systems. However, formal methods seldom interface well with the more informal techniques developed for safety analysis. Action systems is a formal approach to distributed computing that has proven its worth in the design of safety-critical systems. The approach is based on a firm mathematical foundation within which the reasoning about the correctness and behaviour of the system under development is carried out. The purpose of this paper is to show how we can incorporate the results of safety analysis into an action system specification by encoding this information via available composition operators for action systems in order to specify robust and safe controllers.