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Description: A mapping is a class of ordered pairs. (Contributed by NM, 3-Aug-1994) (Proof shortened by Andrew Salmon, 17-Sep-2011)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | fssxp |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | frel | ||
| 2 | relssdmrn | ||
| 3 | 1 2 | syl | |
| 4 | fdm | ||
| 5 | eqimss | ||
| 6 | 4 5 | syl | |
| 7 | frn | ||
| 8 | xpss12 | ||
| 9 | 6 7 8 | syl2anc | |
| 10 | 3 9 | sstrd |