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Description: If the domain of a function is a set, the function is a set. (Contributed by Glauco Siliprandi, 23-Oct-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | fnexd.1 | ||
| fnexd.2 | |||
| Assertion | fnexd |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fnexd.1 | ||
| 2 | fnexd.2 | ||
| 3 | fnex | ||
| 4 | 1 2 3 | syl2anc |