On Friday 30 November 2007 07:32:15 Oscar Gustafsson wrote: > On Thu, 29 Nov 2007, Michael Hennebry wrote: > > Mathematically correct, but one should go for a tighter linear > > relaxation. x[d,h]<=x[d,h+1] > > x[d,h]<=x[d,h+2] > > With this formulation, the latter constraint is redundant. > > x[d,h]<=x[d,h+1] where d indexes a day and h and h+1 index hours. > > Won't this force all the remaining hours of the day to be one? > > On the other hand as the question is formulated it is supposedly what is > going to happen. > > My guess without knowing the context is that it might be better to imply > the three our booking rule in the resource constraints instead of forcing > the next two variables to be one, as this will lead to all preceeding > variables to be one. An alternative might be to have two types of > variables, one that considers the "original" one and one with variables > that are one based on the original ones. > > But considering it is 6:30 in the morning I may be really out of line > here. > > Regards > > Oscar
The problem is a timetabling problem, and indeed there are three indices "x_dhc" standing for day,hours and classroom and there are sessions which has 2, 3 and 4 hours length of duration .I'm trying to allocate available hours of every classroom in a week. -- O. Ican _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
