Programming Language Implementation Let us define functions phi, ECS_Student and M&C_Student, and relation >>>: phi : ECS_speech -> M&C_talk eg. phi "hello" = "" phi "lets have a party" = "bed time" phi "money" = "dole" ECS_Student : situation -> ECS_speech M&C_Student : situation -> M&C_talk phi satisfies the following: All(s:situation . phi x = y => (ECS_Student s = x) /\ (M&C_Student s = y))) >>> : Anything * Anything -> boolean eg. "a world tour" >>> "taking the dog for a walk" = TRUE "the berlin wall" >>> "open university lecturers" = TRUE "the beano" >>> "the telegraph" = TRUE "rowers conversation" >>> "william golding's books" = FALSE "tandoori chicken tikka massalam" >>> "beans on toast" = TRUE Theorem: All(x:ESC_speech . y = phi x => x >>> y) Proof: by inspection. Lots of love, Greg Parker (u87gjp). [IMHO the engineers couldn't understand the course and so had to find some way of getting back at us M&C people. Personally I think these rules are slightly back to front. A better example could be: "5 pints" >>> "10 pints" =TRUE "totally pissed" >>> "still sober" = TRUE Similarly phi "lets have a party" = "so whats new" -sweh]