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Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Power Sets
Functions
opelf
Metamath Proof Explorer
Description: The members of an ordered pair element of a mapping belong to the
mapping's domain and codomain. (Contributed by NM , 10-Dec-2003)
(Revised by Mario Carneiro , 26-Apr-2015)
Ref
Expression
Assertion
opelf
⊢ F : A ⟶ B ∧ C D ∈ F → C ∈ A ∧ D ∈ B
Proof
Step
Hyp
Ref
Expression
1
fssxp
⊢ F : A ⟶ B → F ⊆ A × B
2
1
sseld
⊢ F : A ⟶ B → C D ∈ F → C D ∈ A × B
3
opelxp
⊢ C D ∈ A × B ↔ C ∈ A ∧ D ∈ B
4
2 3
imbitrdi
⊢ F : A ⟶ B → C D ∈ F → C ∈ A ∧ D ∈ B
5
4
imp
⊢ F : A ⟶ B ∧ C D ∈ F → C ∈ A ∧ D ∈ B