Hi Guys I came across a weird bug or maybe it was just me that was doing something stupid. I had this constraint: s.t. overlap1{r in R, j in fr[r]..1}: sum{s in S, i in max(1,j-hs[s]+1)..j} x[s,r,i] <= 1; but GLPK kept violating it. I tried making the sum in the end of my .mod file (after solve;) and I could see that there was a clear violation.
I could see in my shell that it was generating the constraint, but when I checked the output file there was no values for overlap1 like it has just ignored the constraint? I then played a little with the constraint and changed it to:
s.t. overlap1{r in R, j in 1..fr[r]}: sum{s in S, i in max(1,j-hs[s]+1)..j} x[s,r,i] <= 1; only changed "fr[r]..1" to "1..fr[r]" and now it works perfectly. Is there some logical explanation that I'm missing?