Domain filtering

GAMS
1

I tried to make a set of constraints.

It is something like:

set time /t1t4/;
set t(time) /t1t3/;

Variables
A(time)
Equations
Eq1(t)… A(t+1)-A(t) =E= 1;

it is very annoying that even though A(t4) exist, the constrains of Eq(t3) is always become:
0-A(t3) =E= 1;

How can I deal with such situation?
Please tell me the solutions of following two cases：
（1） To make Eq(t3) as “A(t4)-A(t3) =E= 1”;
(2) To exclude Eq(t3);

Thank you very much for your kindly help.

2

Hi Yamaz

See my reply in this post from last week: https://newforum.gams.com/t/equation-based-on-set-number/2003/1

Cheers
Renger

3

Hi Renger,

Thanks very much for your help.
According to that post

I can modify the equation as follow:
Eq1(t) $ (ord(t) ne card(t)) … A(t+1)-A(t) =E= 1;

It works as that it excluded Eq1(t3);

However, what if I what to introduce A(t4) into Eq1(t3) instead of excluding it without expanding the domain, as I mention in Case (1)?
Be noted that A(t4) is also variables but not in the domain of t.

Thanks again for your help

4

set time /t1t4/;
set t(time) /t1t3/;

Variables
A(time)
Equations
Eq1(time)$t(time)… A(time+1)-A(time) =E= 1;