Job scheduling optimiser user case

peterbrydges
peterbrydges
in Modeling

Hi,

 

Has the Anaplan optimiser been succesfully used for a job scheduling problem?

 

Objective is to minimise the time taken to complete a set of jobs.

 

Constraints are:

1) We have a list of resources who can each supply a maximum amount of time per time period.

i.e. Time spent by resource A in period X <= Time available for resource A in period X

 

2) We have a list of jobs to be completed. Each job requires a fixed level of time from each resource to complete.

i.e. Total time required for job by resource A >= Total time spent on job by resource A across all time periods.

 

3) Some jobs cannot be started until other jobs have completed. 

i.e. If task 2 is dependent on task 1 completing.

Time Spent on task 2 in period X =0, if time spent on task 1 >0 in any period >X.

 

Objective is easy to approximate using linear contraints (peanalising future periods very heavily).

Constraint 1 & 2 are easy to deal with using linear constraints.

While contraint 3 can easily also be modelled in Anaplan, I'm not sure how to model it without using logic which is clearly non-linear and thus not compatible with optimiser.

 

If anyone has come across this before, please advise as to whether this is possible?

 

Thanks,

 

Peter.

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Answers

  • samaplan
    samaplan

    Peter,

     

    Optimizer can be configured to have dependent variables constrained by the value of another value in the preceding time period.

     

    I suggest that you separate a given time block into a dynamic time series consisting of hours, blocks, etc. For example, if there are 4 time blocks per day, the variables can be set up like so:

     

    Variable 1: Task 1 Scheduled? (1 = True, 0 = False), dimensionalized by Time Block

    Variable 2: Task 2 Scheduled? (1 = True, 0 = False) dimensionalized by Time Block

     

    List: Time Block with a Previous Property

    Block 1 (Previous: BLANK)

    Block 2 (Previous: Block 1)

    Block 3 (Previous: Block 2)

    Block 4 (Previous: Block 3)

     

    Constraint 1: Task 1 <=1

    Constraint 2: Task 2 <=Task 1[LOOKUP: Previous Time Block]

     

    This will constrain Task 2 so that it can only be scheduled if Task 1 was performed in the previous block. We have some example of this logic in action with a workforce scheduling optimizer where shifts must be contiguous.

     

    --Sam

  • peterbrydges
    peterbrydges

    Hi Sam,

     

    Thank you for your advise.

    Two issues I'm still not sure how to cope with;

     

    1) A task may take multiple periods to complete. We need to define when it has completed rather than just scheduled.

    It maybe that task 1 completes more than one time period before it is optimal to start task 2.

    Thus we cannot just look up the prior time block?

     

    2) I think introducing the additional variables below and linking them to the time the resources spend on the task will make the resource constraint non-linear.

     

    i.e. (Time spent on task 1 by resource A)*(Task 1 Scheduled?)<= Time available for resource A.

    Is of form Variable*Variable<= Constant and thus non-linear.

  • dihya.atmani
    dihya.atmani

    Hello for your 3rd constraint, could you try creating a variable wich is beggining of job 

    You will also create a properties which is ending  of dependant job

    for this property, you will add a formula which says that it is equal to the variable beggining of job + time to achieve the job

    then in your constraint module, you write beggining of job- the properties >= 0

    If you want i can try to do it with you tomorrow, because i don't know if the idea i shared is very clear

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