Editing Communicating sequential processes (section)

=== FDR ===

The most well-known CSP tool is probably ''[[FDR (software)|Failures-Divergences Refinement]]'', which is a commercial product originally developed by Formal Systems (Europe) Ltd. FDR is often described as a [[model checker]], but is technically a ''refinement'' checker, in that it converts two CSP process expressions into [[Labelled transition system|Labelled Transition Systems]] (LTSs), and then determines whether one of the processes is a refinement of the other within some specified semantic model (traces, failures, or failures/divergence).<ref>{{Cite book |first=A. W. |last=Roscoe |chapter=Model-checking CSP |title=A Classical Mind: Essays in Honour of C. A. R. Hoare |publisher=Prentice Hall |date=1994 |author-link=Bill Roscoe}}</ref> FDR applies various state-space compression algorithms to the process LTSs in order to reduce the size of the state-space that must be explored during a refinement check. FDR was succeeded by FDR2, FDR3 and FDR4.<ref>{{cite web |url= https://www.cs.ox.ac.uk/projects/fdr/manual/introduction.html |title=Introduction — FDR 4.2.4 documentation |website=www.cs.ox.ac.uk}}</ref>