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Description: Membership in a positive upper set of integers implies membership in NN . (Contributed by JJ, 1-Oct-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | eluznn |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nnuz | ||
| 2 | 1 | uztrn2 |