> I wondered if there were some special features in GLPK enabling the > use of a non linear constraitn such : > a = 0 or a > 3 .
There is no such feature. However, you can model semicontinuous variables as follows: a >= 3 * z, a <= M * z, where z is an auxiliary binary variable, M is an upper bound of a. _______________________________________________ Help-glpk mailing list Help-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/help-glpk