Description: Combine two sums into a single sum over the cartesian product. (Contributed by Mario Carneiro, 23-Apr-2014)
Ref | Expression | ||
---|---|---|---|
Hypotheses | fsumxp.1 | ||
fsumxp.2 | |||
fsumxp.3 | |||
fsumxp.4 | |||
Assertion | fsumxp |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fsumxp.1 | ||
2 | fsumxp.2 | ||
3 | fsumxp.3 | ||
4 | fsumxp.4 | ||
5 | 3 | adantr | |
6 | 1 2 5 4 | fsum2d | |
7 | iunxpconst | ||
8 | 7 | sumeq1i | |
9 | 6 8 | eqtrdi |