Abstract. This paper presents a formal approach to the evolution of a representation for use in a design process. The approach adopted is based on concepts associated with genetic engineering. An initial set of genes representing elementary building blocks
EVOLVINGBUILDINGBLOCKSFORDESIGNUSINGGENETICENGINEERING:AFORMALAPPROACH.
JOHNS.GEROANDVLADIMIRA.KAZAKOV
KeyCentreofDesignComputing,
DepartmentofArchitecturalandDesignScience,
TheUniversityofSydney,NSW2006Australia.
e-mail:john,kaz@arch.su.edu.au
Abstract.Thispaperpresentsaformalapproachtotheevolutionofarepresentationforuseinadesignprocess.Theapproachadoptedisbasedonconceptsassociatedwithgeneticengineering.Aninitialsetofgenesrepresentingelementarybuildingblocksisevolvedintoasetofcomplexgenesrepresentingtargetedbuildingblocks.Thesetargetedbuild-ingblockshavebeenevolvedbecausetheyaremorelikelytoproducedesignswhichex-hibitdesiredcharacteristicsthanthecommencingelementarybuildingblocks.Thetar-getedbuildingblockscanthenbeusedinadesignprocess.Thepaperpresentsaformalevolutionarymodelofdesignrepresentationsbasedongeneticalgorithmsandusespatternrecognitiontechniquestoexecuteaspectsofthegeneticengineering.Thepaperdescribeshowthestatespaceofpossibledesignschangesovertimeandillustratesthemodelwithanexamplefromthedomainoftwo-dimensionallayouts.Itconcludeswithadiscussionofstyleindesign.
1.Introduction
Thereisanincreasingunderstandingoftherolethatadesignlanguageanditsrep-resentationplayintheef ciencyandef cacyofanydesignprocesswhichusesthatlanguage(Coyneetal.,1990;Geroetal.,1994).Arecurringissueiswhatistheappropriategranularityofalanguage.Ifbuildingblockswhichconstitutetheelementsofadesignmapontoadesignlanguagethenthequestionbecomeswhatisanappropriatescaleforthosebuildingblocksintermsofthe naldesign.Atoneextremewehaveparameterisedrepresentationswherethestructureofadesignis xed,allthevariableswhichgotode neadesignareprede nedandwhatisleftistodeterminethevaluesofthosevariables.Thisde nesaverysmalldesignspace,smallintermsofallthepossibledesignswhichmightbeabletobeproducedforthatdesignsituation.Attheotherextremewehaveelementarybuild-ingblockswhichcanbecombinedinaverylargevarietyofwaysandwhich,asa
Abstract. This paper presents a formal approach to the evolution of a representation for use in a design process. The approach adopted is based on concepts associated with genetic engineering. An initial set of genes representing elementary building blocks
2JohnS.GeroANDVladimirA.
Kazakov
Se
Figure1.
ingblocks,
variables,isthedesignspaceproducedbyallthepossiblecombinationsoftheelementarybuild-isthedesignspaceproducedbyallthecombinationsofthevaluesoftheparameterisedisthedesignspaceofinterestingdesignsforthedesignsituation.
consequencede neaverylargedesignspace,thevastpartofwhichcoversdesignswhicharelikelytobeuninterestingintermsofthecurrentdesignsituation.Thedesignsproducedbytheparameteriseddesignrepresentationsareasubsetofthosecapableofbeingproducedbytheelementarybuildingblockrepresentation,Fig-ure1.Examplesofbuildingblockrepresentationsincludeconstructivesystemssuchasdesigngrammarsasexempli edbyshapegrammars(Stiny,1980b).Ex-amplesofparameterisedvariablerepresentationsincludeawidevarietyofdesignoptimizationformulations(Gero,1985).
Theadvantageoftheuseoftheelementarybuildingblocksrepresentationisthecoverageoftheentiredesignspacetheyprovide,whereastheadvantageoftheparameterisedvariablerepresentationistheef ciencywithwhichasolutioncanbereached.
Wepresenthereaformalapproachwhichgeneratesatargetedrepresentationofadesignproblem.Atargetedrepresentationistheonewhichcloselymapsontotheproblemathand.Asanexampleconsideralayoutplanningprobleminarchi-tecturaldesign.Onerepresentationmaybeatthematerialmolecularlevel,wheremoleculescanbecombinedtomakeavarietyofmaterialsandparticularcombina-tionsinspaceproducephysicalobjects;herethepotentialsolutionspaceincludesdesignswhichbearnorelationstoarchitecture.Atargetedrepresentationsmaybetorepresentroomssuchthatthepotentialsolutionspaceprimarilyincludesdesignswhichareallrecognizablyarchitecturallayouts.
Inordertosimplifyouranalysisweconsiderdesignswhichareassembledfrom
Abstract. This paper presents a formal approach to the evolution of a representation for use in a design process. The approach adopted is based on concepts associated with genetic engineering. An initial set of genes representing elementary building blocks
EvolvingBuildingBlocksforDesignUsingGeneticEngineering
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Figure2.ThesetofbuildingblocksforFroebel’skindergartengifts(Stiny,1980b).
some nitecollectionofspatialelements(wecallthembuildingblocksorcompon-ents)alongwithassemblyrules.Itisassumedthattheassemblyrulesdonotaffectthecomponents-thedesignobjectisaunionofnon-overlappingbuildingblocks.Westartwithsomesetofbuildingblockswhichwecallelementarycomponents.Itisassumedthattheycannotbedecomposedintoanysmallerones.Wecallasetofbuildingcomponentsandassemblyrulesarepresentationofthedesignproblemandthesetofelementarycomponentsandcorrespondingrulesthebasicrepresent-ation.Wecallitarepresentationbecauseitimplicitlyde nesthesetofalldesigns(designstatespace)whichcanbeproducedusingthissetofbuildingblocksandassemblyrules.