Description: The intersection of a singleton is its member. Theorem 70 of Suppes p. 41. (Contributed by NM, 29-Sep-2002)
Ref | Expression | ||
---|---|---|---|
Hypothesis | intsn.1 | |- A e. _V |
|
Assertion | intsn | |- |^| { A } = A |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | intsn.1 | |- A e. _V |
|
2 | intsng | |- ( A e. _V -> |^| { A } = A ) |
|
3 | 1 2 | ax-mp | |- |^| { A } = A |