Abstract
• A specification and implementation of Trylock are given. • The implementation is not correct for branching time (CTL). • The implementation is correct for linear time (LTL). • It follows that LTL is to be preferred over CTL. • The correctness is proved by means of eternity variables. An example is given of a software algorithm that implements its specification in linear time temporal logic (LTL), but not in branching time temporal logic (CTL). In LTL, a prophecy of future behaviour is needed to prove the simulation. Eternity variables are used for this purpose. The final phase of the proof is a refinement mapping in which two threads exchange roles. The example is a software implementation of trylock in a variation of the fast mutual exclusion algorithm of Lamport (1987). It has been used fruitfully for the construction of software algorithms for high performance mutual exclusion.
Highlights
When Dijkstra [4] proposed the mutual exclusion problem in 1965, he more or less apologized for its academic character
The linear time temporal logic (LTL) proof of validity of the implementation is based on simulation, in several phases
The answer is no in branching time temporal logic, but yes in linear time temporal logic
Summary
When Dijkstra [4] proposed the mutual exclusion problem in 1965, he more or less apologized for its academic character. The LTL proof of validity of the implementation is based on simulation, in several phases. The second phase consists of proofs of two progress properties of the algorithm This is done with UNITY logic [2,16]. System TryL has been used previously in the construction of the Triangle Algorithm [12], a mutual exclusion algorithm that is very efficient both under high contention and under low contention This case studies combines and illustrates several aspects of the treatment of shared-variable fine-grain concurrency: temporal logic, simulation, theorem proving, and UNITY.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
