Showing posts with label javapolis. Show all posts
Showing posts with label javapolis. Show all posts

Monday, December 07, 2009

Drools Planner (AKA Drools Solver) Devoxx presentation movie

Thanks to Parleys Beta, I am proud to present:
Examination timetabling with Drools Planner - the movie
Actually, it's not as much a movie as it is a Devoxx 2009 presentation.

Click here to watch it full screen at

I made a few updates since the live presentation at Devoxx, such as the rename from Drools Solver to Drools Planner.

Just before posting this blog, David alerted me of a small (but embarrassing) calculation mistake in one of the slides. Can you find it?

Sunday, November 08, 2009

Drools Solver at Devoxx (Javapolis)

Devoxx (AKA Javapolis) is little more then a week away.

I 'll be holding a BOF presentation about the examination timetabling problem and how I 've solved it with Drools Solver. So you are welcome at my BOF on monday 16 november at 20:00.

Here's a preview of one the slides, which shows a tiny examination instance:

Update: I 've posted an article on DZone which explains that slide in detail.

Wednesday, December 12, 2007

Drools solver Javapolis 2007 slides

The BOF was a success and as promised, I 've posted the slides online:
People asked a bunch of interesting questions afterwards.
One question I felt I left a bit unanswered: how do you weigh your constraints in DRL? So, here's a code example that should answer that question too:

rule "twoExamsInARow"
// ...
insertLogical(new IntConstraintOccurrence(
10, // weight
$leftExam, $rightExam));

rule "twoExamsInADay"
// ...
insertLogical(new IntConstraintOccurrence(
1, // weight
$leftExam, $rightExam));

rule "softConstraintsBroken"
$total : Double() from accumulate(
IntConstraintOccurrence($weight : weight),

So the 2 in a row constraint is 10 times heavier than the 2 in a day constraint.

Tuesday, November 27, 2007

Drools solver @ Javapolis

I 'll hold a Drools Solver BOF at Javapolis 2007 on Tuesday December 11th at 20:00. You're all invited :)
Take a look at the schedule here.
Take a look the contents of the BOF here.

The drools solver manual has also been expanded with more info about the examples:
Take a look at the updated manual here.

The manual now contains some insight about the problem size of the examples. Did you know that the traveling tournament example nl16 finds a feasible solution out of 2,45064610271441678267620602e+259 possible solutions?

And of course I 've added some more eye candy: