Description: Identity function of an opposite category. (Contributed by Mario Carneiro, 2-Jan-2017)
Ref | Expression | ||
---|---|---|---|
Hypotheses | oppcbas.1 | ||
oppcid.2 | |||
Assertion | oppcid |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oppcbas.1 | ||
2 | oppcid.2 | ||
3 | 1 | oppccatid | |
4 | 3 | simprd | |
5 | 4 2 | eqtr4di |