\Ve present a process algebra for mobile processes without bound or free variables. Instead; pointers arc used) that refer back to an action executed in the history of a process. The situation is comparable to a presentation of the '\~cakulus with De Bruijn indices. Note: Report CS~R 02~03) Department of Mathematics and Computer Science) Tedmische Universiteit Eindhoven)

This paper provides a systematic and full treatment of mode transfer operators in process algebra, including complete axiomatizations, operational rules, analysis of expressive power and extensions with timing features. In particular, we study a disrupt operator and an interrupt operator.

Reduction and Topology, p. 28. Non Interleaving Process Algebra, p. 17. Design and Analysis of Dynamic Leader Election Protocols in Broadcast Networks, p. 73. A general conservative extension theorem in process algebra, p. 17. Job Shop Scheduling by Constraint Satisfaction, p. 22. A Hierarchical Membership Protocol for Synchronous Distributed Systems, p. 43. Temporal operators viewed as predicate transformers, p. II. Automatic Verification of Regular Protocols m PIT Nets, p.23. A taxomomy of finite automata construction algorithms, p.87. A taxonomy of finite automata minimization algorithms, p. 23. A precise clock synchronization protocol,p. Treewidth and Patwidth of Cocomparability graphs of Bounded Dimension, p. 14. Browsing Semantics in the "Tower" Model, p. 19. Verifying Sequentially Consistent Memory using Interface Refinement, p. 20. 94/01 P. America M. van der Kammen R.P. Nederpelt O.S. van Roosmalen H.C.M. de Swart 94/02 F. Kamareddine R.P. Nederpelt 94/03 L.B. Hartman K.M. van Hee 94/04 J.C.M. Baeten J .A. Bergstra 94/05 P. Zhou J. Hooman 94/06 T. Basten T. Kunz J. Black M. Coffin D. Taylor 94/07 K.R. Apt R. Bol 94/08 O.S. van Roosmalen 94/09 J .C.M. Baeten J.A. Bergstra 94/10 T. verhoeff 94111 J. Peleska C. Huizing C. Petersohn 94/12 T. Kloks D. Kratsch H. Miiller 94/13 R. Seljee 94114 W. Peremans 94/15 R.J .M. Vaessens E.H.L. Aarts J .K. Lenstra 94116 R.C. Backhouse H. Doornbos 94/17 S. Mauw M.A. Reniers The object-oriented paradigm, p. 28. Canonical typing and n-conversion, p. 51. Application of Marcov Decision Processe to Search Problems, p. 21. Graph Isomorphism Models for Non Interleaving Process Algebra, p. 18. Formal Specification and Compositional Verification of an Atomic Broadcast Protocol, p. 22. Time and the Order of Abstract Events in Distributed Computations, p. 29. Logic Programming and Negation: A Survey, p. 62. A Hierarchical Diagrammatic Representation of Class Structure, p. 22. Process Algebra with Partial Choice, p. 16. The testing Paradigm Applied to Network Structure. p. 31. A Comparison of Ward & Mellor's Transformation Schema with State& Activitycharts, p. 30.

The authors define the alphabet of finite and infinite terms in ACP/sub tau /, the algebra of communicating processes with silent steps, and also give approximations of it. Using the alphabet, they formulate some conditional axioms. The usefulness of the axioms is demonstrated in examples