Neelam Soundararajan

A proof technique for parallel programs

Abstract In this paper we present a set of axioms and rules of inference for a parallel programming language with shared variables and synchronization statements. The important difference between our approach and that of Owicki and Gries (1976) is that our semantics does not contain anything similar to their ‘interference freedom’ check, resulting in a much greater isolation of the proofs of the individual processes than is possible in their system. We illustrate our proof technique with some simple examples.

A distributed deadlock detection and resolution algorithm and its correctness proof

The key idea of the algorithm is to let one transaction controller be in charge of all transactions in a set of interacting transactions. Two transactions are interacting if they are both interested in (accessing) the same resource. In addition, the controller is in charge of all the resources allocated to any of the transactions in the set. Having one controller in charge of all the transactions in a set of interacting transactions and all the resources allocated to them makes it easier to detect deadlocks and avoid them. The main problem dealt with is how a controller takes charge of another transaction when the transaction tries to access one of the resources currently in the control of the controller and how a controller releases a transaction back to its original controller when the transaction is no longer interested in any of the resources in which one or more of the other transactions are also interested. Communicating sequential processes (CSP) is used to code the algorithm. The correctness of the algorithm is proved in a semiformal manner. >

Correctness proofs of CSP programs

Abstract In a research report we have proposed an axiomatic semantics for the language of communicating sequential processes (CSP) of Hoare (1978). In this paper, we use the axiomatic semantics to prove the correctness of a number of CSP programs.

A Proof System for Distributed Processes

A partial correctness proof system for Brinch Hansens Distributed Processes (DP) is presented. Two important aspects of the system are: Proofs of individual processes of a DP program are completely isolated from each other; in particular, no assumptions are allowed in the proof of one process about the behavior of the other processes. Secondly a process is characterized by its externally visible behavior, i.e. the sequence of interactions between this process and the other processes of the program. An example demonstrates the use of the system.

Total correctness of CSP programs

SummaryIn this paper we propose an axiomatic system for proving the total correctness of CSP programs. The system is based on the partial correctness system of [6, 7]. We use the proposed system to prove the total correctness of a program for set partitioning.

Denotational semantics of CSP

Abstract In this paper we propose a new denotational semantics for CSP. The domains used in the semantics are very simple, compared to those used in other approaches to the semantics of CSP. Moreover, our denotations are more abstract than those of the other approaches.