Timo Aaltonen

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Online social media services, such as Facebook and Twitter, have set new standards on how people interact with each other online, share their everyday activities, and media services. While current mobile services supporting social interaction are typically primarily for remote communication, similar services can be introduced to co-located social(More)
Formal methods have been considered one possible solution to the so-called software crisis. Tools are valuable companions to formal methods: they assist in analysis and understanding of formal speci cations and enable the use of rigorous techniques in industrial projects. In this paper, an overview of the new DisCo toolset is given. DisCo is a formal speci(More)
Open source software development has been the subject of interest among businesses as well as in the academic world. OSS enables many possibilities for companies but also sets new kinds of challenges. Because of the characteristics of the OSS phenomenon we propose that trust in OSS communities plays a key role in facilitating their success. Therefore, the(More)
We study a novel type of a semi-supervised anomaly detection problem where the anomalies occur collectively among a background of normal data. Such problem arises in experimental high energy physics when one is trying to discover deviations from known Standard Model physics. We solve the problem by first fitting a mixture of Gaussians to a labeled(More)
Open Source Software (OSS) is currently a widely adopted approach to developing and distributing software. OSS code adoption requires an understanding of the structure of the code base. For a deeper understanding of the maintenance, bug fixing and development activities, the structure of the developer community also needs to be understood, especially the(More)
Complex computer systems are seldom made from scratch but they contain significant amounts of legacy code, which then is under continuous pressure for evolution. Therefore, a need for a rigorous method for managing evolution in this setting is evident. We propose a management method for reactive and distributed systems. The method is based on creating a(More)
In this paper, an approach to the verification of specifications of reactive real-time systems is proposed. DisCo is an object-oriented method based on joint actions. It supports stepwise refinement and specification of real-time properties. A mapping from the DisCo language into timed automata is introduced. Timed automata are finite-state machines(More)