@InProceedings{LIPN-2001-Bec-RTA, author = {Denis B\'echet}, title = {Universal Interaction Systems with Only Two Agents}, booktitle = {Rewriting Techniques and Applications, 12th International Conference, RTA 2001, Utrecht, The Netherlands, May 22--24, 2001. Proceedings}, editor = {Aart Middeldorp}, series = {Lecture Notes in Computer Science (LNCS)}, volume = {2051}, pages = {3--14}, publisher = {Springer-Verlag}, year = 2001, ISBN = {978-3-540-42117-7}, DOI = {10.1007/3-540-45127-7} }