TY - CHAP UR - http://dx.doi.org/10.1007/11580850_5 AV - none TI - A General Name Binding Mechanism N2 - We study fusion and binding mechanisms in name passing process calculi. To this purpose, we introduce the U-Calculus, a process calculus with no I/O polarities and a unique form of binding. The latter can be used both to control the scope of fusions and to handle new name generation. This is achieved by means of a simple form of typing: each bound name x is annotated with a set of exceptions, that is names that cannot be fused to x. The new calculus is proven to be more expressive than pi-calculus and Fusion calculus separately. In U-Calculus, the syntactic nesting of name binders has a semantic meaning, which cannot be overcome by the ordering of name extrusions at runtime. Thanks to this mixture of static and dynamic ordering of names, U-Calculus admits a form of labelled bisimulation which is a congruence. This property yields a substantial improvement with respect to previous proposals by the same authors aimed at unifying the above two languages. The additional expressiveness of U-Calculus is also explored by providing a uniform encoding of mixed guarded choice into the choice-free sub-calculus. M1 - 3705 SN - 3-540-30007-4 T2 - Proceedings of Symposium on Trustworthy Global Computing (TGC ?05) EP - 74 ID - eprints127 N1 - The final publication is available at www.springerlink.com. Y1 - 2005/// SP - 61 T3 - Lecture Notes in Computer Science A1 - Boreale, Michele A1 - Buscemi, Maria Grazia A1 - Montanari, Ugo PB - Springer ED - De Nicola, Rocco ED - Sangiorgi, Davide ER -