Department of Information and Computer Science, Helsinki Institute for Information Technology, Helsinki University of Technology, Finland. jose.caldas@tkk.fi|Department of Information and Computer Science, Helsinki Institute for Information Technology, Helsinki University of Technology, Finland. jose.caldas@tkk.fi|Department of Information and Computer Science, Helsinki Institute for Information Technology, Helsinki University of Technology, Finland. jose.caldas@tkk.fi|Department of Information and Computer Science, Helsinki Institute for Information Technology, Helsinki University of Technology, Finland. jose.caldas@tkk.fi|Department of Information and Computer Science, Helsinki Institute for Information Technology, Helsinki University of Technology, Finland. jose.caldas@tkk.fi