Description: A ring of sets is closed under intersection. (Contributed by Thierry Arnoux, 19-Jul-2020)
Ref | Expression | ||
---|---|---|---|
Hypothesis | isros.1 | |
|
Assertion | inelros | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isros.1 | |
|
2 | dfin4 | |
|
3 | 1 | difelros | |
4 | 1 | difelros | |
5 | 3 4 | syld3an3 | |
6 | 2 5 | eqeltrid | |