What do you mean by "before" in "A needs to be put in a bin before item B"?
(1) B in a bin implies A in the same bin
(2) a bin has some positions, and A must be in a position smaller than B, because for example the bin is a truck and heavy items should be under the light ones.
(3) This term is really related with the time, and this is a scheduling problem.
In the case (3) you can use intervalVariables, and cumul functions should be able to express your capacity constraint.
In (1) and (2), no interval variables needed. Only some additional constraints are to be added.
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Olivier Lhomme
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