Description: A pair containing the empty set is a Moore collection. (Contributed by BJ, 4-Oct-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-pr0moore | |- { (/) , A } e. Moore_ |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 0ex | |- (/) e. _V |
|
| 2 | 0ss | |- (/) C_ A |
|
| 3 | bj-prmoore | |- ( ( (/) e. _V /\ (/) C_ A ) -> { (/) , A } e. Moore_ ) |
|
| 4 | 1 2 3 | mp2an | |- { (/) , A } e. Moore_ |