RE: [Help-glpk] The "dual" suffix and sensitivity to how a constraint is expressed in GMPL

[Andrew Makhorin]

> To me, the only issues are:
> (a) Should GMPL be more clever and check if all the variables are only on one
>  side of the constraint, and if so always place the variables on the 
> left-side,
>  and the constant on the right side, and not multiply by -1?  That would 
> create
>  more intuitive dual variables.

Then it would be unclear what to do, say, with the following constraint:

   x1 + x2 + x3 = x4 + x5 + x6

Besides, in the primal case the rule you suggest is similar to a rule,
when, for example, a variable declared as x <= 0 is replaced by x >= 0
for the same reason.

It seems to me that a "more clever" rule for transforming constraints to
the standard format would be more confusing.