Description: A class is disjoint from its singleton. A consequence of regularity. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (Revised by BJ, 4-Apr-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | disjcsn |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elirr | ||
2 | disjsn | ||
3 | 1 2 | mpbir |