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Mirrors > Home > MPE Home > Th. List > un0 | Structured version Visualization version Unicode version |
Description: The union of a class with the empty set is itself. Theorem 24 of [Suppes] p. 27. (Contributed by NM, 15-Jul-1993.) |
Ref | Expression |
---|---|
un0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | noel 3919 | . . . 4 | |
2 | 1 | biorfi 422 | . . 3 |
3 | 2 | bicomi 214 | . 2 |
4 | 3 | uneqri 3755 | 1 |
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