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Description: Lemma for dath . Show that a second dummy atom d exists outside of the Y and Z planes (when those planes are equal). (Contributed by NM, 15-Aug-2012)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | dalema.ph | ||
| dalemc.l | |||
| dalemc.j | |||
| dalemc.a | |||
| dalem19.o | |||
| dalem19.y | |||
| dalem19.z | |||
| Assertion | dalem19 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | dalema.ph | ||
| 2 | dalemc.l | ||
| 3 | dalemc.j | ||
| 4 | dalemc.a | ||
| 5 | dalem19.o | ||
| 6 | dalem19.y | ||
| 7 | dalem19.z | ||
| 8 | 1 | dalemkehl | |
| 9 | 8 | ad3antrrr | |
| 10 | 1 2 3 4 5 6 | dalemcea | |
| 11 | 10 | ad3antrrr | |
| 12 | simplr | ||
| 13 | 1 5 | dalemyeb | |
| 14 | 13 | ad3antrrr | |
| 15 | 1 2 3 4 5 6 7 | dalem17 | |
| 16 | 15 | ad2antrr | |
| 17 | simpr | ||
| 18 | eqid | ||
| 19 | 18 2 3 4 | atbtwnex | |
| 20 | 9 11 12 14 16 17 19 | syl33anc |