Description: An equality theorem for substitution. (Contributed by NM, 16-May-1993) Revise df-sb . (Revised by BJ, 22-Dec-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | sbequ1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | equeucl | |
|
2 | ax12v | |
|
3 | 1 2 | syl6 | |
4 | 3 | com23 | |
5 | 4 | alrimdv | |
6 | df-sb | |
|
7 | 5 6 | imbitrrdi | |