- EXISTS_DEF
-
|- $? = (\P. P ($@ P))
- TRUTH
-
|- T = (\x. x) = (\x. x)
- FORALL_DEF
-
|- $! = (\P. P = (\x. T))
- AND_DEF
-
|- $/\ = (\t1 t2. !t. (t1 ==> t2 ==> t) ==> t)
- OR_DEF
-
|- $\/ = (\t1 t2. !t. (t1 ==> t) ==> (t2 ==> t) ==> t)
- F_DEF
-
|- F = (!t. t)
- NOT_DEF
-
|- ~ = (\t. t ==> F)
- EXISTS_UNIQUE_DEF
-
|- $?! = (\P. $? P /\ (!x y. P x /\ P y ==> (x = y)))
- LET_DEF
-
|- LET = (\f x. f x)
- COND_DEF
-
|- COND = (\t t1 t2. @x. ((t = T) ==> (x = t1)) /\ ((t = F) ==> (x = t2)))
- ONE_ONE_DEF
-
|- !f. ONE_ONE f = (!x1 x2. (f x1 = f x2) ==> (x1 = x2))
- ONTO_DEF
-
|- !f. ONTO f = (!y. ?x. y = f x)
- TYPE_DEFINITION
-
|- !P rep.
TYPE_DEFINITION P rep =
(!x' x''. (rep x' = rep x'') ==> (x' = x'')) /\
(!x. P x = (?x'. x = rep x'))