Lecture 30:
Distributed Scheduling
© J. Christopher Beck 2008
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Outline
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Overview & Example
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Supply Chain
Distributed Scheduling Exercise
Distributed Timetabling
Optimization and information
engineering issues
© J. Christopher Beck 2008
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Readings
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Gaspero, Mizzaro, & Schaerf, A
MultiAgent Architecture for Distributed
Course Timetabling, Sixth International
Workshop on Distributed Constraint
Reasoning, 2005
© J. Christopher Beck 2008
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Distributed Scheduling
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Same as “normal” scheduling except
there are multiple decision makers
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may control different resources and/or
have different sets of jobs to execute
local problems are inter-dependent
Why distributed?
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real problem is distributed for
geographical, political, or organizational
reasons
© J. Christopher Beck 2008
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Supply Chain Scheduling
© J. Christopher Beck 2008
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Distributed Scheduling
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Local decisions depend on and effect
external events
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Need to coordinate schedules with
suppliers and consumers!
Local decision maker has no control over
others’ schedules
© J. Christopher Beck 2008
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Distributed Scheduling
Exercise: Resource Agent
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You control some units
of a resource
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RED, YELLOW, GREEN,
BLUE
Your goal is to sell the
resource at the highest
price possible
© J. Christopher Beck 2008
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Distributed Scheduling
Exercise: Job Agent
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You have activities to
perform that need resources
You have $1000 to spend
buying resources
Your goal is to buy the
resources required for all
your activities for the least
cost
© J. Christopher Beck 2008
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Distributed Scheduling
Exercise
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To sell/buy a resource
agents must sign each
others sheet noting
quantity and price
Once you have a verbal
agreement – you must
sign!
© J. Christopher Beck 2008
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Distributed Scheduling
Exercise
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Let the games begin!
© J. Christopher Beck 2008
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Distributed Timetabling
Problem
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(See Gaspero et al. paper)
University classroom scheduling
Each department “owns” a set of
classrooms
Each department has a set of courses
to schedule
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Class size, A/V requirements, etc.
© J. Christopher Beck 2008
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Distributed Timetabling
Problem
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Doesn’t have to be distributed
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Departments can make their own
schedules and ignore everyone else
But, if they share rooms maybe everyone
can have a better schedule
No department is willing to give up
authority for its classrooms
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Centralized solution is politically impossible
© J. Christopher Beck 2008
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Distributed Timetabling
Solution
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Decide on a currency
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one student not being able to take a
course = 1 unit of currency
What do they trade?
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roomslots: use a room for a time slot
© J. Christopher Beck 2008
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Distributed Timetabling
Solution
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Somewhat ad hoc solution
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each department creates its own schedule
then a semi-market mechanism is used to
trade roomslots to try an improve
schedules
You should have a general
understanding of the problem solved
and the techniques in this paper
© J. Christopher Beck 2008
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Issues for Distributed
Scheduling
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How much information do
you share?
Who has the authority to make
decisions?
What is the overall scheduling process?
What happens when things go wrong?
© J. Christopher Beck 2008
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