Description: If a class is not an element of another class, it is also not an element of an equal class. Deduction form. (Contributed by David Moews, 1-May-2017)
Ref | Expression | ||
---|---|---|---|
Hypotheses | neleqtrd.1 | |
|
neleqtrd.2 | |
||
Assertion | neleqtrd | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | neleqtrd.1 | |
|
2 | neleqtrd.2 | |
|
3 | 2 | eleq2d | |
4 | 1 3 | mtbid | |