A Finite Equational Base for CCS with Left Merge and Communication Merge

Using the left merge and communication merge from ACP, we present an equational base for the fragment of CCS without restriction and relabelling. Our equational base is finite if the set of actions is finite

Higher-Order Beta Matching with Solutions in Long Beta-Eta Normal Form

Higher-order matching is a special case of unification of simply-typed lambda-terms: in a matching equation, one of the two sides contains no unification variables. Loader has recently shown that higher-order matching up to beta equivalence is undecidable, but decidability of higher-order matching up to beta-eta equivalence is a long-standing open problem. We show that higher-order matching up to beta-eta equivalence is decidable if and only if a restricted form of higher-order matching up to beta equivalence is decidable: the restriction is that solutions must be in long beta-eta normal form

Unique Parallel Decomposition for the Pi-calculus

A (fragment of a) process algebra satisfies unique parallel decomposition if the definable behaviours admit a unique decomposition into indecomposable parallel components. In this paper we prove that finite processes of the pi-calculus, i.e. processes that perform no infinite executions, satisfy this property modulo strong bisimilarity and weak bisimilarity. Our results are obtained by an application of a general technique for establishing unique parallel decomposition using decomposition orders.Comment: In Proceedings EXPRESS/SOS 2016, arXiv:1608.0269

An Interface Theory for Input/Output Automata

Building on the theory of interface automata by de Alfaro and Henzinger we design an interface language for Lynch's Input/Output Automata, a popular formalism used in the development of distributed asynchronous systems, not addressed by previous interface research. We introduce an explicit separation of assumptions from guarantees not yet seen in other behavioral interface theories. Moreover we derive the composition operator systematically and formally, guaranteeing that the resulting compositions are always the weakest in the sense of assumptions, and the strongest in the sense of guarantees. We also present a method for solving systems of relativized behavioral inequalities as used in our setup and draw a formal correspondence between our work and interface automata. Proofs are provided in an appendix

Monotonic Set-Extended Prefix Rewriting and Verification of Recursive Ping-Pong Protocols

Ping-pong protocols with recursive definitions of agents, but without any active intruder, are a Turing powerful model. We show that under the environment sensitive semantics (i.e. by adding an active intruder capable of storing all exchanged messages including full analysis and synthesis of messages) some verification problems become decidable. In particular we give an algorithm to decide control state reachability, a problem related to security properties like secrecy and authenticity. The proof is via a reduction to a new prefix rewriting model called Monotonic Set-extended Prefix rewriting (MSP). We demonstrate further applicability of the introduced model by encoding a fragment of the ccp (concurrent constraint programming) language into MSP

A finite equational base for CCS with left merge and communication merge

Using the left merge and the communication merge from ACP, we present an equational base (i.e., a ground-complete and ω-complete set of valid equations) for the fragment of CCS without recursion, restriction and relabeling modulo (strong) bisimilarity. Our equational base is finite if the set of actions is finite. © 2009 ACM

A finite equational base for CCS with left merge and communication merge

Using the left merge and communication merge from ACP, we present an equational base (i.e., a ground-complete and ¿-complete set of valid equations) for the fragment of CCS without restriction and relabelling. Our equational base is finite if the set of actions is finite

A finite equational base for CCS with left merge and communication merge

Using the left merge and communication merge from ACP, we present an equational base (i.e., a ground-complete and ¿-complete set of valid equations) for the fragment of CCS without restriction and relabelling. Our equational base is finite if the set of actions is finite