Department of Information and Computer Science, Aalto University, FI-00076 AALTO, Finland. tarmo.aijo@aalto.fi|Department of Information and Computer Science, Aalto University, FI-00076 AALTO, Finland. tarmo.aijo@aalto.fi|Department of Information and Computer Science, Aalto University, FI-00076 AALTO, Finland. tarmo.aijo@aalto.fi