Description: Commutative/associative law that swaps the first two terms in a triple sum. (Contributed by Scott Fenton, 9-Mar-2025)
Ref | Expression | ||
---|---|---|---|
Hypotheses | addsassd.1 | ||
addsassd.2 | |||
addsassd.3 | |||
Assertion | adds12d |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | addsassd.1 | ||
2 | addsassd.2 | ||
3 | addsassd.3 | ||
4 | 1 2 | addscomd | |
5 | 4 | oveq1d | |
6 | 1 2 3 | addsassd | |
7 | 2 1 3 | addsassd | |
8 | 5 6 7 | 3eqtr3d |