Deadlock Freedom for Asynchronous and Cyclic Process Networks

This paper considers the challenging problem of establishing deadlock freedom for message-passing processes using behavioral type systems. In particular, we consider the case of processes that implement session types by communicating asynchronously in cyclic process networks. We present APCP, a typed process framework for deadlock freedom which supports asynchronous communication, delegation, recursion, and a general form of process composition that enables specifying cyclic process networks. We discuss the main decisions involved in the design of APCP and illustrate its expressiveness and flexibility using several examples.Comment: In Proceedings ICE 2021, arXiv:2109.14908. arXiv admin note: text overlap with arXiv:2101.0903

A Decentralized Analysis of Multiparty Protocols

Protocols provide the unifying glue in concurrent and distributed software today; verifying that message-passing programs conform to such governing protocols is important but difficult. Static approaches based on multiparty session types (MPST) use protocols as types to avoid protocol violations and deadlocks in programs. An elusive problem for MPST is to ensure both protocol conformance and deadlock freedom for implementations with interleaved and delegated protocols. We propose a decentralized analysis of multiparty protocols, specified as global types and implemented as interacting processes in an asynchronous $\pi$-calculus. Our solution rests upon two novel notions: router processes and relative types. While router processes use the global type to enable the composition of participant implementations in arbitrary process networks, relative types extract from the global type the intended interactions and dependencies between pairs of participants. In our analysis, processes are typed using APCP, a type system that ensures protocol conformance and deadlock freedom with respect to binary protocols, developed in prior work. Our decentralized, router-based analysis enables the sound and complete transference of protocol conformance and deadlock freedom from APCP to multiparty protocols.Comment: revision following anonymous review

Deadlock Freedom for Asynchronous and Cyclic Process Networks (Extended Version)

Establishing the deadlock-freedom property for message-passing processes is an important and challenging problem. This paper considers verification techniques based on behavioral type systems to address the relevant case of processes that communicate asynchronously in cyclic process networks and are governed by session types. We present APCP, a typed process framework for deadlock-freedom which supports asynchronous communication, delegation, recursion, and a form of process composition that enables specifying cyclic process networks. We discuss the main decisions involved in the design of APCP and establish its essential results.Comment: Extended version of arXiv:2110.00146, doi:10.4204/EPTCS.347.

Asynchronous Functional Sessions:Cyclic and Concurrent

We present Concurrent GV (CGV), a functional calculus with message-passing concurrency governed by session types. With respect to prior calculi, CGV has increased support for concurrent evaluation and for cyclic network topologies. The design of CGV draws on APCP, a session-typed asynchronous pi-calculus developed in prior work. Technical contributions are (i) the syntax, semantics, and type system of CGV; (ii) a correct translation of CGV into APCP; (iii) a technique for establishing deadlock-free CGV programs, by resorting to APCP's priority-based type system

Glueballs on S^3

For SU(2) gauge theory on the three-sphere we study the dynamics of the low-energy modes. By explicitely integrating out the high-energy modes, the one-loop correction to the hamiltonian for this problem is obtained. After imposing the $\theta$-dependence through boundary conditions in configuration space, we obtain the glueball spectrum of the effective theory with a variational method.Comment: 3p Latex. Talk presented at LATTICE96(theoretical developments

A decentralized analysis of multiparty protocols

Protocols provide the unifying glue in concurrent and distributed software today; verifying that message-passing programs conform to such governing protocols is important but difficult. Static approaches based on multiparty session types (MPST) use protocols as types to avoid protocol violations and deadlocks in programs. An elusive problem for MPST is to ensure both protocol conformance and deadlock-freedom for implementations with interleaved and delegated protocols. We propose a decentralized analysis of multiparty protocols, specified as global types and implemented as interacting processes in an asynchronous π-calculus. Our solution rests upon two novel notions: router processes and relative types. While router processes use the global type to enable the composition of participant implementations in arbitrary process networks, relative types extract from the global type the intended interactions and dependencies between pairs of participants. In our analysis, processes are typed using APCP, a type system that ensures protocol conformance and deadlock-freedom with respect to binary protocols, developed in prior work. Our decentralized, router-based analysis enables the sound and complete transference of protocol conformance and deadlock-freedom from APCP to multiparty protocols

Session Type Systems based on Linear Logic:Classical versus Intuitionistic

Session type systems have been given logical foundations via Curry-Howard correspondences based on both intuitionistic and classical linear logic. The type systems derived from the two logics enforce communication correctness on the same class of pi-calculus processes, but they are significantly different. Caires, Pfenning and Toninho informally observed that, unlike the classical type system, the intuitionistic type system enforces locality for shared channels, i.e. received channels cannot be used for replicated input. In this paper, we revisit this observation from a formal standpoint. We develop United Linear Logic (ULL), a logic encompassing both classical and intuitionistic linear logic. Then, following the Curry-Howard correspondences for session types, we define piULL, a session type system for the pi-calculus based on ULL. Using piULL we can formally assess the difference between the intuitionistic and classical type systems, and justify the role of locality and symmetry therein.Comment: In Proceedings PLACES 2020, arXiv:2004.0106

One-loop effective action for SU(2) gauge theory on S^3

We consider the effective theory for the low-energy modes of SU(2) gauge theory on the three-sphere. By explicitely integrating out the high-energy modes, the one-loop correction to the hamiltonian for this problem is obtained. We calculate the influence of this correction on the glueball spectrum.Comment: 12p. latex, 3 PostScript figures included (epsf