Description: Lemma for oppfrcl . (Contributed by Zhi Wang, 14-Nov-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | oppfrcl.1 | |- ( ph -> G e. R ) |
|
| oppfrcl.2 | |- Rel R |
||
| Assertion | oppfrcllem | |- ( ph -> G =/= (/) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | oppfrcl.1 | |- ( ph -> G e. R ) |
|
| 2 | oppfrcl.2 | |- Rel R |
|
| 3 | 0nelrel0 | |- ( Rel R -> -. (/) e. R ) |
|
| 4 | 2 3 | ax-mp | |- -. (/) e. R |
| 5 | nelne2 | |- ( ( G e. R /\ -. (/) e. R ) -> G =/= (/) ) |
|
| 6 | 1 4 5 | sylancl | |- ( ph -> G =/= (/) ) |