Re: [Help-glpk] Transport Problem advanced

[Bruno Rosell i Gui]

Hi!
> // s.t. supply{i in I}: sum{j in J} x[i,j] = a[i];
> s.t. supply{i in I}: sum{j in J} x[i,j] = a[i]; // process all offer
>
> s.t. demand{j in J}: sum{i in I} x[i,j] >= b[j];
>
> Now, I need a additional comparison, but not a range from to
> sum{i in I} x[i,j] >= b[j] OR sum{i in I} x[i,j] = 0
>
> How I have to write the syntax?
> Is it still a LP-Problem?
>
> Can someone help me?

It depends if 'b' is a parameter you could use a binary variable ( 'c' ) and 
write:

sum{i in I} x[i,j] >= b[j] * c[j];

 Or you can use something like descirbed in the next posts:
 http://www.mail-archive.com/address@hidden/msg01467.html )
http://www.mail-archive.com/address@hidden/msg00816.html
http://www.mail-archive.com/address@hidden/msg01153.html 
http://www.mail-archive.com/address@hidden/msg02021.html

But if 'b' is a variable , i don't known how to solve

-- 

 Cordialment Bruno Rosell i Gui