Metamath Proof Explorer


Definition df-funALTV

Description: Define the function relation predicate, i.e., the function predicate. This definition of the function predicate (based on a more general, converse reflexive, relation) and the original definition of function in set.mm df-fun , are always the same, that is ( FunALTV F <-> Fun F ) , see funALTVfun .

The element of the class of functions and the function predicate are the same, that is ( F e. FunsALTV <-> FunALTV F ) when F is a set, see elfunsALTVfunALTV . Alternate definitions are dffunALTV2 , ... , dffunALTV5 . (Contributed by Peter Mazsa, 17-Jul-2021)

Ref Expression
Assertion df-funALTV ( FunALTV 𝐹 ↔ ( CnvRefRel ≀ 𝐹 ∧ Rel 𝐹 ) )

Detailed syntax breakdown

Step Hyp Ref Expression
0 cF 𝐹
1 0 wfunALTV FunALTV 𝐹
2 0 ccoss 𝐹
3 2 wcnvrefrel CnvRefRel ≀ 𝐹
4 0 wrel Rel 𝐹
5 3 4 wa ( CnvRefRel ≀ 𝐹 ∧ Rel 𝐹 )
6 1 5 wb ( FunALTV 𝐹 ↔ ( CnvRefRel ≀ 𝐹 ∧ Rel 𝐹 ) )