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# How to code Summation of V(w)-element of-W in constraints?

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Hi! We were able to execute the model already but we're having warnings that the result for this column is similar with the other column. Take for example the constraints 22 and 26? How do we code the "summation"? Sorry I'm just a beginner and I have no one to teach me and I only have a month to study everything because the deadline is just for 2 months.

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Best answer by mohansx 5 June 2019, 19:58

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Userlevel 5
+5
@pamjsnn

warnings that the result for this column is similar with the other column

You can ignore this warning if your model is solving in reasonable time. It just means that there are columns in your math program who have the same coefficients in all the rows, and you can have non-unique solutions. i.e., different values for the variables but the same objective value. You can read more if you go to Settings -> Project Options and search for duplicate column

For summation, the syntax is:

code:
`sum[index, Identifier(Index)]`

So, for your equation 22 - contraint_22(v)

code:
`sum[k|k in (K - Kv), X(v, k) ] = 0`

Here, k is an index in set K, Kv is a subset of set K. You will read this constraint as,

For all v, sum of X(v, k) over k for k in set K but not in subset Kv must be equal to 0
Userlevel 6
+6
Hi @pamjsnn have you looked at the AIMMS language reference? You can search within the pdf itself, maybe what you're looking for is in the Summation section 12.1.5 starting on the book page numbered 176 (pdf page 200).

https://documentation.aimms.com/aimms_ref.html

Hope that helps!