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Description: Cyclically shifting a word two times is commutative. (Contributed by AV, 21-Apr-2018) (Revised by AV, 5-Jun-2018) (Revised by Mario Carneiro/AV, 1-Nov-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 2cshwcom |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | zcn | ||
| 2 | zcn | ||
| 3 | addcom | ||
| 4 | 1 2 3 | syl2anr | |
| 5 | 4 | 3adant1 | |
| 6 | 5 | oveq2d | |
| 7 | 2cshw | ||
| 8 | 7 | 3com23 | |
| 9 | 2cshw | ||
| 10 | 6 8 9 | 3eqtr4rd |