What does “subject to” mean in reference to Sigma math notation?

Question

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I understand the first part, but what does the “subject to” part mean?

Help? Couldn’t find anything on google searching “sigma subject to”.

In: 1

Answer 1

In this case, it means a constraint on the “min” in the previous problem. You want to find the *x*’s that minimize the sum x0 + x1 + x2 + … + x_(n-1), but you’re only considering candidate options that satisfy the requirement that sum x_i * c_i = S. Other choices for x aren’t allowed.