Accessing the last element of a variable in GAMS -

i have set:

set t /t1*t6/;

let consider there variable called var. have constraint last element of var less 20.

variable var(t);

equation const;

const..

var('t6') < 20;

i replace 't6' in last line card(t), if size of t changes not have change manually.

you can use dollar condition limit equation last period:

const(t)$(card(t)).. var(t) < 20; 

or define singleton subset end condition so:

singleton set tend(t); tend(t) = yes$(card(t));  const.. var(tend) < 20;