Description: Value of the indicator function where it is 0 . (Contributed by Thierry Arnoux, 14-Aug-2017)
Ref | Expression | ||
---|---|---|---|
Assertion | ind0 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eldifi | |
|
2 | indfval | |
|
3 | 1 2 | syl3an3 | |
4 | eldifn | |
|
5 | 4 | 3ad2ant3 | |
6 | 5 | iffalsed | |
7 | 3 6 | eqtrd | |