Originally posted by: Kyle_Wang

Hi Dear Friend

     I want to assign some tasks to be finished by a group of people with different working calendar. each worker works 12 hours, but my tasks can start at anytime within 1 shift and requires more than 1 people to complete.  for example, if shift1 starts at 8am and ends at 8pm, task1 start at 11am ends at 11pm, which means the task1 only can partially finished in shift1, and need to pick up 2 person from shift2 to finish the rest of the work.    Can you educate me how to model scenario i mentioned above. i have been stuck there for a while already:)  thanks! 

Originally posted by: Kyle_Wang

Seems I should put it under generic CP forum.. appreciate if admin can delete it.

Originally posted by: Petr Vilím

Hello,

it depends on what are other constraints in your problem. In the example it seems that there are 2 workers working in each shift. Is it always like that, or the number of workers can differ from shift to shift? Could the workers work at more than one task simultaneously? For example, in shift1 worker1 can work on taskX while worker2 work on taskY? Are the workers interchangeable? For example, worker1 and worker2 works together in shift1 but only worker1 is skilled enough to work on taskX.

If the problem is really simple (always same number of workers, workers are interchangeable) then I suggest to forget about the workers and shift completely: just assume that there is a cumulative (or disjunctive - noOverlap) resource that is available all the time. What worker and what shift is just a detail that could be determined once a solution is found. The solver does not have to deal with this level of detail. If it is not your case please explain what is the additional complication.

Best, Petr