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Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Union
Relations and functions (cont.)
funrnex
Metamath Proof Explorer
Description: If the domain of a function exists, so does its range. Part of Theorem
4.15(v) of Monk1 p. 46. This theorem is derived using the Axiom of
Replacement in the form of funex . (Contributed by NM , 11-Nov-1995)
Ref
Expression
Assertion
funrnex
⊢ dom ⁡ F ∈ B → Fun ⁡ F → ran ⁡ F ∈ V
Proof
Step
Hyp
Ref
Expression
1
funex
⊢ Fun ⁡ F ∧ dom ⁡ F ∈ B → F ∈ V
2
1
ex
⊢ Fun ⁡ F → dom ⁡ F ∈ B → F ∈ V
3
rnexg
⊢ F ∈ V → ran ⁡ F ∈ V
4
2 3
syl6com
⊢ dom ⁡ F ∈ B → Fun ⁡ F → ran ⁡ F ∈ V