Votail: A Formally Specified and Verified Ballot Counting System for Irish PR-STV Elections

Votail is an open source Java implementation of Irish Proportional Representation by Single Transferable Vote (PR-STV). Its functional requirements, derived from Irish electoral law, are formally specified using the Business Object Notation (BON) and refined to a Java Modeling Language (JML) specification. Formal methods are used to verify and validate the correctness of the software. This is the first public release of a formally verified PR-STV open source system for ballot counting and the most recent of only about half a dozen releases of formally verified e-voting software