Hi Tim,
this is kind of dilemma for me, I see that people on this list are a bit
careful about not spoiling homeworks :-) I'm going to help you a bit though.
Let's use the 3rd possibility :-) (Of course there are many more.) I see
that you constrain a task to a specified time interval (using something
like "TestVal=<:Start.P" etc.). Additionaly, you want to exclude all
tasks from some interval, say, "I". For each task, you could specify -
before you search for a solution - that it occurs either before or after
I. Now there are 2^n combinations, see? So we have 2^n problems, all of
which differ in which tasks must occur before I and which occur after I.
You already know how to constrain a task to a specified interval, so you
should be able to solve these 2^n problems and pick your favorite solution.
The nice thing about Oz is that you can make a non-deterministic choice
inside of a search script. (See the "choice" statement.) This enables
you to solve only one problem instead of the 2^n (in fact, you still
solve 2^n problems, but you can express it using a single script).
Hope this helps,
Filip
Thanks for the ideas. I did know about these possibilities. What I am
having trouble with is actually implementing them.
Could you give me a small example of each? I would really, really,
appreciate it.
Hi,
generally, you have 2 possibilities.
The first is to constrain the task start so that the task can not
intersect the interval (e.g. using the \=: operator). You know the task
length, so no problem here.
The other option is even easier: create an artificial fixed task that
occupies the resource during the outage.
Cheers,
Filip
/ Hi All,
/>/ />/ I have been studying very hard and have finally created an
application />/ that will schedule tasks in oz. What is confusing me is
how to do the />/ following:
/>/ />/ 1. Don't schedule tasks for a certain time frame on a
particular />/ resource (Either because the resource is down for
repairs/unavailable or />/ because a task has already been started and
needs to finish)
/>/ />/ The lines that deal with this in my code are:
/>/ />/ fun {Compile Problem}
/>/ TaskSpec = Problem.tasks
/>/ Dur = {GetDur TaskSpec}
/>/ TestVal = 10
/>/ TestVal2 = 15
/>/ in
/>/ proc {$ Start}
/>/ Start={GetStart TaskSpec}
/>/ {ForAll TaskSpec
/>/ proc {$ T}
/>/ {ForAll {CondSelect T pre nil}
/>/ proc {$ P}
/>/ Start.P + Dur.P =<: Start.{Label T}
/>/ TestVal =<: Start.{Label T}
/>/ TestVal =<: Start.P
/>/ %% Start.P + Dur.P =<: TestVal2
/>/ %% Start.P \=: TestVal
/>/ %% Start.P \=: TestVal2
/>/ end}
/>/ end}
/>/ {Record.forAll Start proc {$ S}
/>/ S={FD.reflect.min S}
/>/ end}
/>/ end
/>/ />/ end
/>/ />/ I can get it to start from a certain point or not schedule after
a />/ certain point, but I can't figure out how to make the constraints
such />/ that tasks will be scheduled before a reserved time frame and
after. />/ Any ideas/help would be greatly appreciated. By the way I
am very />/ impressed with mozart oz. I am somewhat of a newbie to
constraint />/ programming but this made it easy to begin./
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