@conference {34, title = {Roles in Collaborative Activity}, booktitle = {Second Hellenic Conference on Artificial Intelligence, SETN 02}, volume = {2308}, year = {2002}, month = {00/2002}, pages = {449 - 460}, publisher = {LNCS - Springer Verlag}, organization = {LNCS - Springer Verlag}, address = {Thessaloniki, Greece}, author = {I. Partsakoulakis and G. Vouros}, editor = {I. Partsakoulakis} }