Description: Binary relation form of OutsideOf . Theorem 6.4 of Schwabhauser p. 43. (Contributed by Scott Fenton, 17-Oct-2013) (Revised by Mario Carneiro, 19-Apr-2014)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | broutsideof |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-outsideof | ||
| 2 | 1 | breqi | |
| 3 | brdif | ||
| 4 | 2 3 | bitri |