Description: If a class is contained in a difference, it is contained in the minuend. (Contributed by David Moews, 1-May-2017)
Ref | Expression | ||
---|---|---|---|
Assertion | difss2 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id | |
|
2 | difss | |
|
3 | 1 2 | sstrdi | |