© J. Christopher Beck 2008 1

Lecture 30: Distributed Scheduling

© J. Christopher Beck 2008 2

Outline Overview & Example

Supply Chain Distributed Scheduling Exercise

Distributed Timetabling Optimization and information

engineering issues

© J. Christopher Beck 2008 3

Readings

Gaspero, Mizzaro, & Schaerf, A MultiAgent Architecture for Distributed Course Timetabling, Sixth International Workshop on Distributed Constraint Reasoning, 2005

© J. Christopher Beck 2008 4

Distributed Scheduling

Same as “normal” scheduling except there are multiple decision makers may control different resources and/or

have different sets of jobs to execute local problems are inter-dependent

Why distributed? real problem is distributed for

geographical, political, or organizational reasons

© J. Christopher Beck 2008 5

Supply Chain Scheduling

© J. Christopher Beck 2008 6

Distributed Scheduling

Local decisions depend on and effect external events Need to coordinate schedules with

suppliers and consumers! Local decision maker has no control

over others’ schedules

© J. Christopher Beck 2008 7

Distributed Scheduling Exercise: Resource Agent

You control some units of a resource RED, YELLOW, GREEN,

BLUE Your goal is to sell

the resource at the highest price possible

© J. Christopher Beck 2008 8

Distributed Scheduling Exercise: Job Agent

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 9

Distributed Scheduling Exercise

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 10

Distributed Scheduling Exercise

Let the games begin!

© J. Christopher Beck 2008 11

Distributed Timetabling Problem

(See Gaspero et al. paper) University classroom scheduling Each department “owns” a set of

classrooms Each department has a set of

courses to schedule Class size, A/V requirements, etc.

© J. Christopher Beck 2008 12

Distributed Timetabling Problem

Doesn’t have to be distributed 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 Centralized solution is politically

impossible

© J. Christopher Beck 2008 13

Distributed Timetabling Solution

Decide on a currency one student not being able to take a

course = 1 unit of currency What do they trade?

roomslots: use a room for a time slot

© J. Christopher Beck 2008 14

Distributed Timetabling Solution

Somewhat ad hoc solution 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 15

Issues for Distributed Scheduling

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?