Re: [Help-glpk] setting lower bound on variable with LPM

[Andrew Makhorin]

>I have a problem setting the lower bound of a set of variables:
>e.g.
>
>sets I = (I1, I2);
>
>variables x[I],y;
>
>x[i].lo = nil; KO !!
>y.lo = nil; OK
>
>How do I fix the lower bound on x ?

The left part 'x[i].lo' is syntactically invalid. Should write

   x.lo[i] := nil;

because lower bounds are defined by members of the *implicit* model
parameter x.lo, which is introduced into model automatically once the
variable x has been declared, i.e. as if there were the declaration

   parameter x.lo[I];

>Moreover, is it possible to define sets with integer elements like
>sets J = (1,2);
>and better with a range like
>sets J = 1..2;
>?

In the current version of the language unsigned integers can't be used
as set items, and reduced forms like 1..2 are also not allowed.

Do you think it'd be reasonable to include these features in the
language?