Keep me out of the loop: a more flexible choreographic projection

Choreographic programming is a paradigm where programmers write global descrip- tions of distributed protocols, called choreographies, and correct implementations are au- tomatically generated by mechanism projection. Not all choreographies pro- jectable, because decisions made one process must be communicated to other processes whose behaviour depends on them – property known as knowledge choice. The standard formulation choice disallows protocols such third-party authentication with retries, two iteratively interact, wait notified at the end this loop. In work we show how can weakened, extending class projectable these interesting behaviours. whole development formalised in Coq. Working proof assistant was crucial our development, help it provided detecting counterintuitive edge cases that would otherwise have gone unnoticed.