So in the paper found here:
https://link.springer.com/article/10.1007/BF01819761
We find this theorem here . I was having difficulty parsing the actual notation they're using and want to program this algorithm. But I don't understand what that second summation is even doing. Is $j_i$ the first element of the set of values input to the function or does it start at one and sum to that term? What is $j_t$ or even $s_t$ going to be equal to at any step of that final product term? There's a lot going on here and it's hard to read.
