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how can I model the incremental summation of one variable in GAMS constraints like the following:

y(t) is variable;

t is period index that t=1,…,4;

in constraints section I want this summation in each period:

t=1 : y(t=1) < t * 10
t=2 : y(t=2) < t * 10 – y(t=1)
t=3 : y(t=3) < t * 10 – y(t=2) – y(t=1)
t=4 : y(t=3) < t * 10 – y(t=3) – y(t=2) – y(t=1)
Bista
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user6831558
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1 Answers1

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set t /1,2,3,4/;
* Create an alias of set t
alias (t,t1);
variable y(t);
equation incremental_summation(t);

* use ord and $-condition to formulate your equation
incremental_summation(t)..
y(t) <= t * 10 - sum(t1$(ord(t1)<ord(t)),y(y));
Catyes
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