Re: [rules-users] Continuous Planning values for task planning
Hi Geoffrey, I managed to implement the solution with the relative end Times. (I haven't yet used the incremental score calculation because I haven't quite understood how I implement it) However I am facing one problem with our approach: Lets say we have 3 tasks A, B, and C, each of duration 1 just for simplicity, with these constraints: a) B can only start between A.endTime + 10 and A.endTime + 100 b) C can only start between A.endTime + 50 and A.endTime + 100 c) C can only start between B.endTime + 10 and B.endTime + 20 With our approach of B.startTime = max(prev.endTime, A.endTime + 10) B will always be scheduled to start at time 11 (and end at time 12) given the hard constraints above. On the other hand C cannot start before time 51, thus violating constaint C. The only solution to this would be to move B forward to start at time 30. Is there any technique to detect these situations and make such adjustments? thanks again, Josef On 20 August 2012 09:46, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote: You 'll want incremental score calculation (with delta's) for your end times. http://docs.jboss.org/drools/release/5.4.0.Final/drools-planner-docs/html_single/index.html#incrementalScoreCalculation So that naturally puts the calculation of those end times in the scoreDRL (or IncrementalJavaCalculator if you're not using drools). Whether or not that endTime should be a property on the model (at least the model that Planner works with), is an open design question. If it isn't, you can use insertLogicals in DRL, like I did in nurserostering to calculate the number of sequential weekends being worked etc. If it is a property on your model, either the DRL must first correct it (with higher salience rules for example), or custom moves must correct it as they are being done (which is very hard as it entails constraints functionality). As for the cloning: it's quite simple: Either the model's entity contains the endTime property, then clone it. If it doesn't, then there's nothing to clone. I don't see any problems related to the cloning. Op 18-08-12 01:53, Josef Bajada schreef: Hi Geoffrey, Following your advice and after gaining some more understanding of planner, I think approaching the problem as a chain of tasks one of the other makes sense. It would have some 'wait' time between tasks where the end time of the previous task is smaller than the minimum time the task has to wait after its dependency (which could be different from the previous task). I've noticed that in most examples (TSP and VRP), there is some separation between the model and the planning entity that is being moved around in the chain, which also makes sense. (For instance in TSP, Visit is the planning entity while City is the data entity). When the planning entity gets cloned, the data entity gets assigned to the clone. I am concerned however, that with my dependency between tasks and their end times (which are as such a property of the planning entity not the data entity) I won't be able to model them in this way. (For a task to know whether it has violated its hard constraint it needs to get access to the end time of its dependency, which is in the planning entity). My concern is that I might end up with a whole mess when it comes to the cloning of tasks. I am also concerned about the performance of computing the end time of each node recursively based on its previous task and dependent tasks. What is the best approach in this case? thanks, Josef On 25 July 2012 08:30, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote: Op 24-07-12 23:14, Josef Bajada schreef: Hi Geoffrey, Thanks for your reply. Does it make sense to wait longer than 7 mins after task A (presuming no other task forces occupies the user at that time)? Put differently: Can we say that the starting time of B = Math.max((endTime of task before B), (endTime of task A + 7 minutes))? If we can say that, it's pointless to investigate the solutions where task B starts 8 minutes after task A and the user doing no task that last minute. Yes, the starting time of B = Math.max((endTime of task before B), (endTime of task A + 7mins)) as long as it is smaller than (endTime of task A + 8mins). Yes, it is pointless to investigate the solutions where task B starts 8 minutes after task A and the user doing no task that last minute. The 8 minute is just a constraint that the task in between tasks A and B cannot take longer than 7:59s. I am thinking that maybe instead of using time itself as the planning variable, we would use time just to determine the Hard and Soft scores. So if Task B is scheduled after Task A + 8mins by the solver, then it inflicts on the hard score. Similarly if Task B is scheduled before Task A + 7 mins. Does my reasoning make sense in any way? Yes, but personally, I 'd design it differently (although I have no proof that my way would be better), like
Re: [rules-users] Continuous Planning values for task planning
Hi Geoffrey, Following your advice and after gaining some more understanding of planner, I think approaching the problem as a chain of tasks one of the other makes sense. It would have some 'wait' time between tasks where the end time of the previous task is smaller than the minimum time the task has to wait after its dependency (which could be different from the previous task). I've noticed that in most examples (TSP and VRP), there is some separation between the model and the planning entity that is being moved around in the chain, which also makes sense. (For instance in TSP, Visit is the planning entity while City is the data entity). When the planning entity gets cloned, the data entity gets assigned to the clone. I am concerned however, that with my dependency between tasks and their end times (which are as such a property of the planning entity not the data entity) I won't be able to model them in this way. (For a task to know whether it has violated its hard constraint it needs to get access to the end time of its dependency, which is in the planning entity). My concern is that I might end up with a whole mess when it comes to the cloning of tasks. I am also concerned about the performance of computing the end time of each node recursively based on its previous task and dependent tasks. What is the best approach in this case? thanks, Josef On 25 July 2012 08:30, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote: Op 24-07-12 23:14, Josef Bajada schreef: Hi Geoffrey, Thanks for your reply. Does it make sense to wait longer than 7 mins after task A (presuming no other task forces occupies the user at that time)? Put differently: Can we say that the starting time of B = Math.max((endTime of task before B), (endTime of task A + 7 minutes))? If we can say that, it's pointless to investigate the solutions where task B starts 8 minutes after task A and the user doing no task that last minute. Yes, the starting time of B = Math.max((endTime of task before B), (endTime of task A + 7mins)) as long as it is smaller than (endTime of task A + 8mins). Yes, it is pointless to investigate the solutions where task B starts 8 minutes after task A and the user doing no task that last minute. The 8 minute is just a constraint that the task in between tasks A and B cannot take longer than 7:59s. I am thinking that maybe instead of using time itself as the planning variable, we would use time just to determine the Hard and Soft scores. So if Task B is scheduled after Task A + 8mins by the solver, then it inflicts on the hard score. Similarly if Task B is scheduled before Task A + 7 mins. Does my reasoning make sense in any way? Yes, but personally, I 'd design it differently (although I have no proof that my way would be better), like this: Task B is scheduled after Task A + 8mins by the solver = make this a hard constraint Task B is scheduled before Task A + 7 mins = make this a build-in hard constraint (= not a constraint in the scoreDRL or ScoreCalculator, but by design, see manual). Each Task is assigned to a previousTaskOrPerson (and this variable is chained). It does not know it's startingTime directly. The scoreDRL or ScoreCalculator calculates the startingTime of a Task dynamically, by applying this logic: starting time of B = Math.max((endTime of previousTaskOrPerson of B), (endTime of task A + 7mins)) Note: Chained=true guarantees that there are no cycles of Tasks and that no Tasks exists with a previousTaskOrPerson == null. Note: (endTime of task A + 7mins) is not hard coded in the score function: you won't find 7 or A in there. thanks, Josef On 24 July 2012 20:46, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote: Op 23-07-12 16:26, Josef Bajada schreef: Hi Geoffrey, Well I want to leave 'space' between tasks in the situations where there are hard constraints that require me to put this space. This makes the chaining technique harder to model, but I wouldn't write it off yet. As a simple example: Task A: Put pasta in boiling water (duration 40 seconds) Task B: Take pasta out of boiling water (duration 50 seconds, cannot start before 7 mins after Task A finishes, cannot start after 8 mins after Task A finishes) Does it make sense to wait longer than 7 mins after task A (presuming no other task forces occupies the user at that time)? Put differently: Can we say that the starting time of B = Math.max((endTime of task before B), (endTime of task A + 7 minutes))? If we can say that, it's pointless to investigate the solutions where task B starts 8 minutes after task A and the user doing no task that last minute. If we can say that, then chaining can calculate the the starting time of a task on the fly differently. Task C: Chop vegetables (duration 2 minutes). This will evidently leave some gaps. The ideal result from the solver should be: Task A: at time 0 (ends at 40s) Task C: at time 41s (ends
Re: [rules-users] expert mailing list
Agreed. I think a parallel list for all sub projects of Drools makes sense. From my side I am mostly interested in Planner so a planner-us...@lists.jboss.org would also be good for me. On 15 August 2012 10:18, Wolfgang Laun wolfgang.l...@gmail.com wrote: From my point of view, the user list is becoming increasingly cluttered with Qs regarding Guvnor, which doesn't interest me at all. A parallel list guvnor-us...@lists.jboss.org might help. -W On 15 August 2012 10:12, Michael Anstis michael.ans...@gmail.com wrote: Personally, I don't find the user list high volume. Perhaps re-categorizing the mailing lists we have works better:- - users: newbie type stuff - dev (rename drools-tech?): technical questions (not just implementation) My 2c. On 15 August 2012 00:33, Salaboy sala...@gmail.com wrote: Probably a linked in private group can do the job, I dont know if it supports all the features that you mention but at least you have the contacts network to checks who joins and post new topics. With a group of moderators the topics can be restricted easily Sent from my iPhone On 14 Aug 2012, at 22:48, Mark Proctor mproc...@codehaus.org wrote: As the user list is now high volume, i'm contemplating an invite only expert list. I'm not sure who this would work, or if it's practical. But the idea is to have a lower volume list, with a higher quality of technical questions and discussions. This might make it easier for people to be engaged. I'm thinking of doing it as a google group drools-expert-group or something. I'm not entirely sure how to decide who gets an invite or not…. as it's very arbitrary. I guess in general anyone who gets a recommendation for someone on the list, gets an invite. But I'm open to other ideas to run this. Ideally we should be able to setup a number of moderators, that can handle this invite list, including people from the community. Although not sure if google groups supports this, need to find out. Anyway would like to here what people think, and would be interest to see alternative ways to do this. Maybe you can point to existing setups, that manage this sort of situation, that we can copy? Mark ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Continuous Planning values for task planning
Hi Geoffrey,
Thanks for your reply.
Does it make sense to wait longer than 7 mins after task A (presuming no
other task forces occupies the user at that time)?
Put differently: Can we say that the starting time of B =
Math.max((endTime of task before B), (endTime of task A + 7 minutes))?
If we can say that, it's pointless to investigate the solutions where
task B starts 8 minutes after task A and the user doing no task that last
minute.
Yes, the starting time of B = Math.max((endTime of task before B), (endTime
of task A + 7mins)) as long as it is smaller than (endTime of task A +
8mins).
Yes, it is pointless to investigate the solutions where task B starts 8
minutes after task A and the user doing no task that last minute.
The 8 minute is just a constraint that the task in between tasks A and B
cannot take longer than 7:59s.
I am thinking that maybe instead of using time itself as the planning
variable, we would use time just to determine the Hard and Soft scores.
So if Task B is scheduled after Task A + 8mins by the solver, then it
inflicts on the hard score. Similarly if Task B is scheduled before Task A
+ 7 mins.
Does my reasoning make sense in any way?
thanks,
Josef
On 24 July 2012 20:46, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote:
Op 23-07-12 16:26, Josef Bajada schreef:
Hi Geoffrey,
Well I want to leave 'space' between tasks in the situations where there
are hard constraints that require me to put this space.
This makes the chaining technique harder to model, but I wouldn't write it
off yet.
As a simple example:
Task A: Put pasta in boiling water (duration 40 seconds)
Task B: Take pasta out of boiling water (duration 50 seconds, cannot start
before 7 mins after Task A finishes, cannot start after 8 mins after Task A
finishes)
Does it make sense to wait longer than 7 mins after task A (presuming no
other task forces occupies the user at that time)?
Put differently: Can we say that the starting time of B =
Math.max((endTime of task before B), (endTime of task A + 7 minutes))?
If we can say that, it's pointless to investigate the solutions where task
B starts 8 minutes after task A and the user doing no task that last minute.
If we can say that, then chaining can calculate the the starting time of a
task on the fly differently.
Task C: Chop vegetables (duration 2 minutes).
This will evidently leave some gaps. The ideal result from the solver
should be:
Task A: at time 0 (ends at 40s)
Task C: at time 41s (ends at 2:41)
Task B: at time 7:40
There is a gap between C and B which is OK.
If another Task is added to the story:
Task D: Prepare sauce (duration 7 minutes)
I would want the following result:
Task A: at time 0 (ends at 40s)
Task D: at time 41s (ends 7:41s)
Task B: at time 8:42s (ends 9:32s)
Task C: at time 9:33s (ends 11:33s)
Task C can actually take place before Task A too.
I still need to read and understand the chaining functionality properly.
Do you think it would allow me to achieve the above?
I don't know.
But using continuous variables in a search problem such as this that
smells discrete with discrete constraints (A must start before B, ...),
could blow up the search space unnecessarily.
If you want to look into using continuous variables: the support for it is
limited currently.
you can reuse the Drools Planner metaheuristic algorithms (including
termination, score, ...), but there's no decent generic move factory
support for continuous variables yet.
So you 'll have to write a custom MoveFactory that creates a limited
subset of moves.
Also, construction heuristics can't handle continuous variables yet, so
you 'll have to write a custom SolutionIntializer.
There are examples with a custom MoveFactory and a custom
SolutionIntializer where you can copy paste from, but none with continuous
variables at the moment.
thanks,
Josef
On 22 July 2012 20:05, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote:
Presuming that you don't want to leave space between tasks, you can
design your model differently by using the chained functionality:
it will be far more efficient and the planning variable won't be
continuous.
Let's presume you're scheduling Tasks to Persons.
@PlanningEntity
class Task implements TaskOrPerson {
...
@PlanningVariable(chained = true)
@ValueRanges({
@ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
solutionProperty = taskList),
@ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
solutionProperty = personList,
excludeUninitializedPlanningEntity = true)})
public TaskOrPerson getPreviousTaskOrPerson() {
return previousTaskOrPerson;
}
public int getDuration() {
return duration;
}
public int getStartingTime() {
int startingTime = 0;
TaskOrPerson taskOrPerson = getPreviousTaskOrPerson();
while (taskOrPerson
Re: [rules-users] Continuous Planning values for task planning
Hi Geoffrey,
Well I want to leave 'space' between tasks in the situations where there
are hard constraints that require me to put this space.
As a simple example:
Task A: Put pasta in boiling water (duration 40 seconds)
Task B: Take pasta out of boiling water (duration 50 seconds, cannot start
before 7 mins after Task A finishes, cannot start after 8 mins after Task A
finishes)
Task C: Chop vegetables (duration 2 minutes).
This will evidently leave some gaps. The ideal result from the solver
should be:
Task A: at time 0 (ends at 40s)
Task C: at time 41s (ends at 2:41)
Task B: at time 7:40
There is a gap between C and B which is OK.
If another Task is added to the story:
Task D: Prepare sauce (duration 7 minutes)
I would want the following result:
Task A: at time 0 (ends at 40s)
Task D: at time 41s (ends 7:41s)
Task B: at time 8:42s (ends 9:32s)
Task C: at time 9:33s (ends 11:33s)
Task C can actually take place before Task A too.
I still need to read and understand the chaining functionality properly. Do
you think it would allow me to achieve the above?
thanks,
Josef
On 22 July 2012 20:05, Geoffrey De Smet ge0ffrey.s...@gmail.com wrote:
Presuming that you don't want to leave space between tasks, you can
design your model differently by using the chained functionality:
it will be far more efficient and the planning variable won't be
continuous.
Let's presume you're scheduling Tasks to Persons.
@PlanningEntity
class Task implements TaskOrPerson {
...
@PlanningVariable(chained = true)
@ValueRanges({
@ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
solutionProperty = taskList),
@ValueRange(type = ValueRangeType.FROM_SOLUTION_PROPERTY,
solutionProperty = personList,
excludeUninitializedPlanningEntity = true)})
public TaskOrPerson getPreviousTaskOrPerson() {
return previousTaskOrPerson;
}
public int getDuration() {
return duration;
}
public int getStartingTime() {
int startingTime = 0;
TaskOrPerson taskOrPerson = getPreviousTaskOrPerson();
while (taskOrPerson instanceof Task) { // Every chain is
guarantee to end up with an anchor (= Person)
startingTime += ((Task) taskOrPerson).getDuration();
taskOrPerson = ((Task)
taskOrPerson).getPreviousTaskOrPerson()
}
return startingTime;
}
}
class Person implements TaskOrPerson {
}
For a good example, take a look at the VehicleRouting example.
For more info about chaining, in the manual see section 4.3.4.2.6. Chained
http://docs.jboss.org/drools/release/5.4.0.Final/drools-planner-docs/html_single/index.html
Op 22-07-12 18:00, Josef Bajada schreef:
Hi,
I am new to Drools and Drools Planner, so apologies if I am asking
anything obvious.
My objective is to implement a simple (for now) planner which schedules
tasks according to 2 main criteria:
- Their duration (in seconds)
- Their dependencies on other tasks (e.g. Hard Constraint that Task B has
to start between 180 and 200 seconds after Task A finishes).
Since there are gaps between dependent tasks as part of the hard
constraints other tasks can be fitted in between dependent tasks.
So the Solver needs to find the optimal start time for each task that
satisfies the hard constraints, and in the shortest total timeline possible
to complete all tasks (soft constraint).
The main problem I am finding is that this start time, which is
essentially the planning variable is a continuous variable.
Chapter 4 of the Drools documentation mentions very briefly (Section
4.3.4.1) that planning variables can be continuous, but there does not
seem to be any more details about how to achieve this.
Even if the planning variable was discrete (say bins of 5 second
intervals), there is no upper bound as such.
How is it best to handle such planning variables in Drools Planner?
thanks,
josef
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--
With kind regards,
Geoffrey De Smet
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[rules-users] Continuous Planning values for task planning
Hi, I am new to Drools and Drools Planner, so apologies if I am asking anything obvious. My objective is to implement a simple (for now) planner which schedules tasks according to 2 main criteria: - Their duration (in seconds) - Their dependencies on other tasks (e.g. Hard Constraint that Task B has to start between 180 and 200 seconds after Task A finishes). Since there are gaps between dependent tasks as part of the hard constraints other tasks can be fitted in between dependent tasks. So the Solver needs to find the optimal start time for each task that satisfies the hard constraints, and in the shortest total timeline possible to complete all tasks (soft constraint). The main problem I am finding is that this start time, which is essentially the planning variable is a continuous variable. Chapter 4 of the Drools documentation mentions very briefly (Section 4.3.4.1) that planning variables can be continuous, but there does not seem to be any more details about how to achieve this. Even if the planning variable was discrete (say bins of 5 second intervals), there is no upper bound as such. How is it best to handle such planning variables in Drools Planner? thanks, josef ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
