Re: [Help-glpk] Ordered bin packing

2013-01-27 Thread Jeffrey Kantor
Dmitri, One unanswered question is to equalize the bin weights as much as possible subject to tighest packing. Below is a solution. There's probably a more elegant formulation. In any event, you now have solutions to special cases of your more general multiobjective problem. -- minimize maximu

Re: [Help-glpk] Ordered bin packing

2013-01-27 Thread Dmitri Goutnik
Jeff, Wow, thanks a lot! That is exactly what I was looking for. Best regards, Dmitri On 27/01/2013, at 14:17, Jeffrey Kantor wrote: > Dmitri, > > This is a problem with two objectives which, depending on problem data, may > conflict with each other. So the best we can do is to find tradeo

Re: [Help-glpk] Ordered bin packing

2013-01-27 Thread Jeffrey Kantor
Dmitri, This is a problem with two objectives which, depending on problem data, may conflict with each other. So the best we can do is to find tradeoffs between the conflicting objectives. Here's one solution where alpha is a parameter expressing the relative significance of the two objectives. s

Re: [Help-glpk] Ordered bin packing

2013-01-27 Thread Dmitri Goutnik
Hi Jeff, Thanks, yes that would be preferable packing. My goal is to pack items as "tightly" as possible while preserving even (within some predefined margin) weight distribution between bins. Best regards, Dmitri On 27/01/2013, at 13:40, Jeffrey Kantor wrote: > Hi Dmitri, > > This could be

Re: [Help-glpk] Ordered bin packing

2013-01-27 Thread Jeffrey Kantor
Hi Dmitri, This could be done through the objective function. But before going there, I'm wondering a bit about the solution you're showing for your example. Wouldn't you want move item 7 from Bin 3 to Bin 2 to meet your primary objective? Jeff On Sun, Jan 27, 2013 at 1:34 PM, Dmitri Goutnik

[Help-glpk] Ordered bin packing

2013-01-27 Thread Dmitri Goutnik
Hello everyone, I modified bpp.mod to pack items in predefined number of bins of unlimited capacity so that weight is (approximately) evenly distributed between bins. In addition to weight, each item has an "order" or "position". Is there a way to write an additional model constraint so that it