> Don't worry, I think this has nothing to do with global economics or > worldwide peace. > > I have a model which, when run, glpk advises me that it has discovered > 162 hidden inequalities. I assume in the model and not the world, > because 162 would seem small for the world. Also the numbr varies with > the data I supply to the model and its difficult to see how that would > affect the world. > > What are they? Both in a general sense, what are hidden inequalities? > and in the particular case of my model, how do I investigate them? > > Are they a good or a bad thing? The model works quickly and produces > correct answers. Should every model have some? How have I induced them? > > LPs for a long time have had only two objectives, min and max, and they > are really the same. Perhaps it is time for a new objective to find the > data with the minimum hidden inequalities, which is presumably the > fairest solution. >
Cover inequality is an inequality in the form x1 + x2 + ... + xn >= 1 where x1, x2, ..., xn are binary variables. It means that at least one xj should be 1 in any integer feasible solution. Hidden cover inequality is an inequality which doesn't have the form above, but is equivalent to some cover inequality. For example, 2x1 + 3x2 + 2x3 >= 2 is hidden cover inequality, because it is equivalent to and therefore can be replaced by the following cover inequality: x1 + x2 + x3 >= 1 Such replacements are used internally by the mip preprocessor, and you may just ignore all messages concerning details of the preprocessing. _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
