Description: Swap 2nd and 3rd members of an unordered triple. (Contributed by NM, 22-May-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | tpcomb | |- { A , B , C } = { A , C , B } |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | tpcoma | |- { B , C , A } = { C , B , A } |
|
2 | tprot | |- { A , B , C } = { B , C , A } |
|
3 | tprot | |- { A , C , B } = { C , B , A } |
|
4 | 1 2 3 | 3eqtr4i | |- { A , B , C } = { A , C , B } |