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Mirrors > Home > NFE Home > Th. List > df-domfn | GIF version |
Description: Define the domain function. This is a function wrapper for the domain operator. (Contributed by Scott Fenton, 9-Aug-2019.) |
Ref | Expression |
---|---|
df-domfn | ⊢ Dom = (x ∈ V ↦ dom x) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cdomfn 5769 | . 2 class Dom | |
2 | vx | . . 3 setvar x | |
3 | cvv 2859 | . . 3 class V | |
4 | 2 | cv 1641 | . . . 4 class x |
5 | 4 | cdm 4772 | . . 3 class dom x |
6 | 2, 3, 5 | cmpt 5651 | . 2 class (x ∈ V ↦ dom x) |
7 | 1, 6 | wceq 1642 | 1 wff Dom = (x ∈ V ↦ dom x) |
Colors of variables: wff setvar class |
This definition is referenced by: fvdomfn 5868 domfnex 5870 |
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