Description: There is exactly one element in a singleton. Exercise 2 of TakeutiZaring p. 15. This variation requires only that B , rather than A , be a set. (Contributed by NM, 12-Jun-1994)
Ref | Expression | ||
---|---|---|---|
Hypothesis | elsn2.1 | |
|
Assertion | elsn2 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elsn2.1 | |
|
2 | elsn2g | |
|
3 | 1 2 | ax-mp | |