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Description: Subset relation for Cartesian product. (Contributed by Jeff Hankins, 30-Aug-2009)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | xpss2 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ssid | ||
| 2 | xpss12 | ||
| 3 | 1 2 | mpan |