One Jump Ahead: Computer Perfection at Checkers

571 Pages·2009·5.07 MB·English

by  Jonathan Schaeffer (auth.)

One Jump Ahead

Computer Perfection at Checkers

Revised Edition
One Jump Ahead

Computer Perfection at Checkers

Revised Edition

Jonathan Schaeffer

1 3
Author
Jonathan Schaeffer
Department of Computing Science
University of Alberta
Edmonton, Alberta
Canada T6G 2E8
[email protected]

ISBN: 978-0-387-76575-4 e-ISBN: 978-0-387-76576-1
DOI: 10.1007/978-0-387-76576-1

Library of Congress Control Number: 2008931408

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StephandRebecca
fortheirpatienceandlovethroughout.
It’sfinallyover.Really!
Preface
It’shardtobelievethatit’sbeenoveradecadesinceOneJumpAhead:Challenging
Human Supremacy at Checkers was published. I’m delighted to have the opportu-
nitytoupdateandexpandthebook.Thefirsteditionendedonasadnoteandthat
was reflected in the writing. It is now eleven years later and the project has come
to a satisfying conclusion. Since its inception, the checkers project has consumed
eighteenyearsofmylife—twentyifyoucountthepre-CHINOOKandpost-solving
work.It’shardformetobelievethatIactuallystuckwithitforthatlong.Mywife,
Steph,wouldprobablyhavesomethingwittytosayaboutmyobsessivebehavior.
Rereadingthebookafteradecadewasdifficultforme.WhenIoriginallywrote
OneJumpAhead,Ivowedtobecandidinmytellingofthestory.Thatmeantbeing
honestaboutwhatwentrightandwhatwentwrong.Ihavebeencriticizedforbeing
hardonsomeofthecharacters.Thatmaybeso,butIhopeeveryonewillagreethat
thepersonreceivingthemostcriticismwas,justifiably,me.Itriedtobebalancedin
thestorytelling,reflectingthingsastheyreallyhappenedandnotassomesanitized
everyone-lived-happily-ever-aftertale.IwasappreciativeofPaulLu’scommentson
thebook,sinceheapparentlyreadmymindonthismatter:
Another strength of this book is how Jonathan fearlessly pulls no punches in presenting
balancedportraitsofthemanypeopleinvolvedintheCHINOOKstory.Don’texpectafor-
gettablepuffpiece.Scientistsandchampionsarenotimmunefromhumanfoibles.Indis-
pellingthatillusion,Jonathantellsahonestandvaluablestory.NobodyescapesJonathan’s
(sometimes)sharpcriticism:notmyself(deserved),notsomeoftheluminariesofcheckers
(accurate,inmyopinion),andespeciallynotJonathanhimself.ButJonathanbalancesthis
withgenuinepraise,affection,andrespectinalmosteverycase.Consequently,thebook
containsmanyinsightsonhumannature,thenatureofAI,andwhathappenswhenthey
crosspaths.
Withadecadebetweenreadingsofthebook,evenIwassurprisedatmycandor.
OccasionallyIhadtowinceandevenblushatthememoriesthatthebookevoked.
DidIreallydothat?WhyonEarthwouldIcommitthattopaperandlettheworld
know?WasIcrazy?Probably.
Whyshouldyoubotherreadingthisedition,giventhatyoureadthefirstedition?
ThenewOneJumpAheaddifferssignificantly:
vii
viii One Jump Ahead
1. Fivenewchaptersthatbringthestoryfrom1996toitssuccessfulconclusionin
2007.Thestoryofsolvingcheckersaddsanewdimensiontothequesttoprove
computersuperiorityovertheincredibleabilitiesofDr.MarionTinsley.
2. Sevennewchaptersthatgivethekeyparticipantsachancetotelltheirsideofthe
story.Theoriginalbookreflectedmyopinion;theothermajorplayersneededa
publicforumtogivetheirrecollectionsandexpresstheirviews.
3. Additionalanecdotesfrom1989to1996thatdidn’tmaketheoriginalcut.Idon’t
recallwhyIdecidedtoleavethemout.Imayhavehadagoodreasonbackthen,
butifIcan’trecallittodaythenthereason(s)couldn’thavebeenthatimportant.
4. Manymorephotos!Thishelpsbringsomeofthecharacterstolife.
5. Thetexthasbeenimproved,includingcorrectionsandupdates.
This book was written for a variety of audiences. First and foremost, it was in-
tendedforreaderswithaninterestincomputingscience,specificallyartificialintel-
ligenceandsoftwareengineering.Despitewhatpeoplemaythink,especiallywhen
theyopenthecoverandseediagramsofcheckerspositions,thisbookisaboutcre-
ating technology. It is the story of an incredibly-talented, almost-perfect checkers
player, Marion Tinsley, and our attempts to create a computer program that could
match his abilities. That may sound rather dry, but I like to think that the human
elementmakesthisaninterestingstory.
Second, I tried to write it at a level that would make it accessible to a general
audience.Iwantedtocreateabookthateducatedpeopleaboutcomputingscience
andthechallengesposedbydevelopingcomplexartificialintelligencesystems.
Third,thebookisforcheckersplayers.TheyareangrywithmebecauseIused
algebraic notation for specifying checkers moves instead of their much-loved (but
obscure) numeric notation. The change was an attempt to make the checkers con-
tent more accessible to a wider audience. I came to appreciate the beauty of the
game, and I wanted to communicate this to as wide an audience as possible. The
communityisshrinking,andasacompetitivesportmayonedaydie.Ihopethatin
my writing I have captured an accurate snapshot of the historic tradition, talented
people,andcollegialatmospherethatcharacterizethisnoblegame.
In this book you will see the evolution of hardware technology. We go from
computer speeds that went from megahertz (millions of instructions per second)
togigahertz(billionspersecond),computermemorythatstartedoutatmegabytes
(millions of bytes) and ended up at hundreds of gigabytes (hundreds of billions),
andmegabytedisksizesthatgrewintoterabytes(thousandsofbillions).Thisbook
is not a quaint story of old technology. The story and the lessons learned are as
valuabletodayastheywerewhentheeventsunfolded.Scientistswillalwayspush
theenvelopeofwhatistechnologicallypossible.Someonewithalargeproblemmay
bestartingwithgigabytes(109)todayandendupusingpetabytes(1015)tomorrow.
Ihavebeenfortunatetobepartofauniqueexperience.Alongmyeighteenyear
odyssey, I was privileged to work with, interact with, and compete against many
wonderfulpeople.Iwanttothankeveryonewhomadethisadventurepossible.
June2008 JonathanSchaeffer
Acknowledgments
TheCHINOOKandsolving-checkersprojectswereteameffortsfromstarttofinish.
The story is told from my point of view, but that has the disadvantage of down-
playingthecontributionsoftheotherplayers.Ihavetriedtorectifythis,inpart,by
givingthema voiceinthisbook: thekeyplayerswere eachaskedtowrite ashort
chapter on their experiences. This adventure wouldn’t have been possible without
hugecommitmentsfrommanypeople.Thisstory,despitethemanyupsanddowns,
was a wonderful experience for me and for the members of our team. I want to
extendmydeepestheart-feltthankstoallofthemfortheirselflesscontributions.
The book has been enriched by the personal reflections of Martin Bryant,
Neil Burch, Rob Lake, Paul Lu, Rebecca Schaeffer, Steph Schaeffer, and Norman
Treloar.Thankyou!
NumerouspeoplecontributedtohelpingmaketheupdatedversionofOneJump
Ahead possible: Darse Billings, Yngvi Bjo¨rnsson, Neil Burch, Robert Holte, An-
dreasJunghanns,RobertLake,AnnNield,RebeccaSchaeffer,andStephSchaeffer.
Additionalphotographsweresupplied(withpermission)byRichardFortman,Fred-
erick Friedel, Richard Pask, Steph Schaeffer, Richard Siemens (University of Al-
bertaCreativeServices),andGioWiederhold.RobLakewrotethesoftwareneeded
todothecheckersdiagrams.
I received valuable input from Richard Pask. His 1997 letter to me was full of
insightsandnewmaterial.Hisbook,TheLegendaryMFT,wasavaluablesourceof
information.Thebookisatourdeforceandmusthavebeenalaboroflove.
ThankyoutoSpringer-Verlagforgivingmetheopportunitytocompletethestory
ofmycheckerssagainprint.MelissaFearonandValerieSchofieldshepherdedme
throughtheprocess.
A project like this would not have been possible without research funding. Al-
berta’s Informatics Circle of Research Excellence (iCORE) and Canada’s Natural
SciencesandEngineeringResearchCouncil(NSERC)supportedmywork.
Finally,foreighteenyearstheDepartmentofComputingScienceattheUniver-
sityofAlbertaprovidedthebackdropforthisstory.Ithasbeenaprivilegetowork
insuchanoutstandingandcollegialenvironment.
ix
Preface (1997)
WhydidIwritethisbook?I’mstillnotsure.Afterall,I’maresearcher,whichmeans
I know how to write technical papers. But writing for a non-technical audience is
somethingIknownothingabout.IttookalotofeffortbeforeIcouldforcemyself
tositdowntowritethefirstword.OnceIdid,however,itwashardtostop!When
I started this project, I didn’t know that I had a lot to say and, in some sense, the
resultsshowthis.ThebookismuchlongerthanIeverimagineditwouldbe.Worse
yetisthatthereisalotofmaterialthatIdecidednottoinclude.It’sagoodthingthat
the publishers decided to limit how long the book could be! However, after much
soulsearching,IthinkInowknowwhyIwrotethisbook.
First and foremost, this book tells an interesting story. It’s about the life of a
checkers-playing computer program, CHINOOK, from its creation in 1989 to its
retirement in 1996. In reality the story revolves around two people with different
views of the program. As the creator of CHINOOK, I wanted to push the program
to become the best player in the world, in much the same way that a father might
encouragehissontoexcelatsports.Theworldcheckerschampion,MarionTinsley,
sawtheprogramasathreattohisincredibleplayingrecordandhislegitimateclaim
tobethebestplayerever.Theresultwasapublicbattlebetweenmanandmachine
forsupremacyatcheckers.Infact,itreallywasaprivatecontestofmanversusman.
A second reason was to alleviate what I perceive to be a void in the literature.
There are many interesting computer “story” books around, detailing such topics
asthehistoryofcomputing,companies,personalities,andevenafewontechnical
products. But I don’t know of any that go into the intimate details of creating a
computer program, specifically an “intelligent” one. Tracy Kidder’s The Soul of a
New Machine, recounting the birth of a computer chip, was the closest model to
whatIwantedtoachieve.Infact,TheSoulofanIntelligentProgramwasaworking
titleforthisbookatonetime.
Thethirdreasonhastodowiththeeducatorinme.IhopedthatIcouldwritea
lucidaccountofthetrialsandtribulationsofdevelopingacomplexcomputerpro-
gram. I wanted to educate people on the difficulties of writing computer software
andgivearealistic,understandableexplanationofthelatestcomputingtechnology.
xi
xii One Jump Ahead
Thefinalreasonispersonal,andthisistheonethatIhadtocometogripswith.
I feel a lot of dissatisfaction about the way the story ends. By forcing myself to
expressmyfeelingsinwords,ithasgivenmethechancetocontemplatewhatI’ve
accomplishedand,finally,allowmetorestoremyprideintheproject.
TherewasatremendoustemptationtowriteabookthatglorifiedtheCHINOOK
project,makingitsoundlikeacarefullyplanned,well-thought-outresearcheffort.
Of course, this is baloney. Instead I decided to write a book that tried to show the
realityofresearch:personalityconflicts,money,stupiderrors,badideas,obsession,
frustration, and the impact on the family. A friend of mine, on reading an early
draftofthebook,said,“Youcomeacrossasacompletejerk.”Theearlydraftswere
cruderwithmorepersonal“editorialcomments”interspersedthatdidn’tsurviveto
thefinaledition.Itriedtobehonest,eventothepointofsayingsomeunflattering
things about myself. I think this was necessary to give readers a flavor of what
reallywenton.A“sanitized”versionofthestorywouldn’tbeasinterestingandas
informative.Nevertheless,IhopeIdon’tcomeacrossasajerk!
Apologies:
The book presents many things from my point of view and, unfortunately, often
does not properly reflect the time and effort put in by other members of the team.
Everyoneofthemworkedveryhardandputinlonghours.Pleaseacceptmysincere
apologiesifIhavefailedtoacknowledgeyourcontributionproperly.
Beforeyoureadthisbook:
Computer people: Don’t let the checkers-related material turn you off. Ignore it.
Nevertheless,Iencourageyoutotrytounderstandwhat’sgoingoninthecheckers
diagramsorplaythroughsomeofthegames.Youmightdiscoverthatyouactually
understandtheprincipleswithminimaleffort.Bewarethough:thegameisaddictive!
Checkersplayers:Don’tdwellonthecomputermaterial.Ignoreit.Nevertheless,
IhopeIhaveexplainedtheconceptsatahighenoughlevelthatyouwon’twantto
skipthem!
Fortherecord:
Ihadaseriousdilemmainwritingthisbook.Doyousaycheckerplayerorcheck-
ersplayer?Logically,itmadesensetocallaplayerofcheckersacheckersplayer.
However,Iquicklydiscoveredthatthecheckerscommunity(orisitcheckercom-
munity?) preferred the former. David Kramer did some research on this issue and
wrote:
After consulting Al Lyman, editor of the ACF Bulletin; a linguist at the University of
Toronto;theworldauthorityonbilliards,agamewithasimilarpluralproblem;andnu-