I am facing a problem with Gams modeling, and will be very appreciated if someone can help me.

I define:

set t

variable x(t).

I want to express this equation as a constraint in my model:

x(t=T)>=sum(t,x(t<=T-1))

which means the variable *x* at time slot *t* should be equal or larger than the sum of *x* at all time slot before *t*.

I tried a lot of ways to express it as an equation in Gams, but all of them doesn’t work. Can someone here help me dealing with this? Thanks!

Lawrence