Description: The value of a class exists. Corollary 6.13 of TakeutiZaring p. 27. (Contributed by NM, 30-Dec-1996)
Ref | Expression | ||
---|---|---|---|
Assertion | fvex | ⊢ ( 𝐹 ‘ 𝐴 ) ∈ V |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-fv | ⊢ ( 𝐹 ‘ 𝐴 ) = ( ℩ 𝑥 𝐴 𝐹 𝑥 ) | |
2 | iotaex | ⊢ ( ℩ 𝑥 𝐴 𝐹 𝑥 ) ∈ V | |
3 | 1 2 | eqeltri | ⊢ ( 𝐹 ‘ 𝐴 ) ∈ V |