Concurrency, i.e. the domain in computer science which deals with parallel (asynchronous) computations, has very strong links with algebraic topology; this is what we are developing in this paper, giving a survey of \geometric" models for concurrency. We show that the properties we want to prove on concurrent systems are stable under some form of deformation, which is almost homotopy. In fact, ...

Since long-lived computations (e.g. workflow systems) cannot be realized with classical transactions, extended models have been developed to support this special class of executions with proper semantics. The main problem with these new models is the lack of an extended concurrency control mechanism which makes it possible to use all advanced features of the new methods. This article presents a...

Transaction management comprises diierent aspects such as concurrency control, recovery control, and replication control. Usually, only one or at least two of these aspects are considered in theories of transaction management|the other aspects are ignored. In this paper, we propose a model of executions that allows to capture all three aspects of transaction management. Based on this execution ...

Directed Algebraic Topology is a recent field, deeply linked with Category Theory. A 'directed space' has directed homotopies (generally non reversible), directed homology groups (enriched with a preorder) and fundamental n-categories (replacing the fundamental n-groupoids of the classical case). Applications have been mostly developed in the theory of concurrency. Unexpected links with noncomm...

Reasoning about concurrent programs is challenging, especially if data shared among threads. Program correctness can be violated by the presence of races—whose prevention has been a topic concern both in research and practice. The Rust programming language prime example, putting slogan fearless concurrency practice not only employing an ownership-based type system for memory management, but als...