Description: Two ways to say that A is a nonzero ordinal number. (Contributed by Mario Carneiro, 21-May-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | ondif1 | |- ( A e. ( On \ 1o ) <-> ( A e. On /\ (/) e. A ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dif1o | |- ( A e. ( On \ 1o ) <-> ( A e. On /\ A =/= (/) ) ) |
|
2 | on0eln0 | |- ( A e. On -> ( (/) e. A <-> A =/= (/) ) ) |
|
3 | 2 | pm5.32i | |- ( ( A e. On /\ (/) e. A ) <-> ( A e. On /\ A =/= (/) ) ) |
4 | 1 3 | bitr4i | |- ( A e. ( On \ 1o ) <-> ( A e. On /\ (/) e. A ) ) |