Description: A setvar variable is always interchangeable with itself. (Contributed by AV, 29-Jul-2023)
Ref | Expression | ||
---|---|---|---|
Assertion | ichid |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sbid | ||
2 | 1 | sbbii | |
3 | sbid2vw | ||
4 | 2 3 | bitri | |
5 | 4 | gen2 | |
6 | df-ich | ||
7 | 5 6 | mpbir |