Re: [Help-glpk] Sign of an integer

[hamsda9]

Andrew Makhorin wrote:
> 
>> var sx{a in A, b in B}, binary;
>> /* sx[a,b] is sign(sum{c in C} x[a,b,c]) */
>> /* in other word, sx[a,b] is logical_or{c in C} x[a,b,c] */
>> 
>> s.t. foo{a in A, b in B}: sum{c in C} x[a,b,c] <= card(C) * sx[a,b];
>> 
>> s.t. rooms{a in A}: sum{b in B} sx[a,b] <= r;
> 
> Incorrect. The first constraint must be the following:
> 
> s.t. foo{a in A, b in B}:
>      0 <= card(C) * sx[a,b] - sum{c in C} x[a,b,c] <= card(C) - 1;
> 
> 

Thanks you really helped me out, it worked like a charm.

I gotta say, the way you transformed this problem and solved it with your 
  0 <= card(C) * sx[a,b] - sum{c in C} x[a,b,c] <= card(C) - 1;
equation is just genius and an amazing idea. You sure are a very intellgent
person.

You have my deepest respect and appreciation.
Thanks again.
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