pr : type. at : type. a : at. b : at. atomic : at -> pr. t : pr. f : pr. and : pr -> pr -> pr. or : pr -> pr -> pr. imp : pr -> pr -> pr. true : pr -> type. %mode true *P. true/ti : true t. true/andi : true (and A B) <- true A <- true B. true/ori1 : true (or A B) <- true A. true/ori2 : true (or A B) <- true B. true/impi : true (imp A B) <- (true A -> true B). true/ande1 : true A <- true (and A B). true/ande2 : true B <- true (and A B). true/impe : true B <- true (imp A B) <- true A. true/ore : true C <- true (or A B) <- (true A -> true C) <- (true B -> true C). true/fe : true C <- true f.