杜剑锋 Protege教程.ppt

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1、Protg Tutorial主讲：杜剑峰Protg Tutorial:OverviewnSession 1:Interface basicsnSession 2:Defining a vegetarian pizza2nReview:OWL BasicsnIntro:Protg-OWLnInterface:Creating ClassesnConcept:DisjointnessnInterface:Creating PropertiesnConcept:Describing ClassesnInterface:Creating RestrictionsSession 1:Interface

2、Basics3Review of OWLOWLnis a W3C standard Web Ontology Languagencomes in 3 flavours(Lite,DL and Full)qwe are using OWL DL(Description Logic)qDL=decidable fragment of First Order Logic(FOL)nis generally found in RDF/XML syntaxnis therefore not much fun to write by handSo,we have tools to help us4OWL

3、ConstructsPersonCountry=class(concept)Animal=individual(instance)BelgiumParaguayChinaLatviaElvisHaiHolgerKylieS.ClausRudolphFlipper=property(relationship)lives_inlives_inlives_inhas_pethas_pet5Get Protg-OWL1.Go to:http:/protege.stanford.edu/download/registered.html2.Download full Protg 3.3.1(a relea

4、sed version)3.Install the software Logon to Windows6Starting Protg-OWL1.Select“New Project”2.Select“OWL/RDF Files”Run Protg.exe7Protg OWL pluginProtg tabs8Protg OWL plugin:TabsUsed in this tutorialChanging the GUITop-level functionalityPopulating the modelExtensions(visualisation)9Classes Tab10Class

5、esTab:Asserted Class HierarchySubsumption hierarchy(superclass/subclass)Structure as asserted by the ontology engineerCreate and Delete classes(actually subclasses!)Everything is a subclass of owl:ThingSearch for class11ClassesTab:Class Editor12ClassesTab:Class EditorClass annotations(for class meta

6、data)Class name and documentationSwitch view to show Properties“available”to ClassDisjoints widgetConditions WidgetClass-specific tools(find usage etc)1314Create Classes1.Click the“Create subclass”button(this is above the class hierarchy)A new class will be created as a subclass of owl:Thing2.Type i

7、n a new name“DomainConcept”over the default(press“enter”updates the hierarchy)3.Req.for later labs:document your class using the rdfs:comment field4.Create another class called“Pizza”by clicking the“Create subclass”You will notice that Pizza has been created as a subclass of DomainConcept as this wa

8、s the class selected when the button was pressed.You can also right-click any class and select“Create Class”5.Create two more subclasses of DomainConcept called“PizzaTopping”and“PizzaBase”.Any mistakes,use the“Delete Class”button next to“Create Class”Start with your empty ontology15DisjointnessnOWL

9、assumes that classes overlapPizzaPizzaTopping=individualThis means an individual could be both a Pizza and a PizzaTopping at the same timeWe want to state this is not the case16DisjointnessnIf we state that classes are disjointThis means an individual cannot be both a Pizza and a PizzaTopping at the

10、 same timeWe must do this explicitly in the interfacePizzaPizzaTopping=individual17ClassesTab:Disjoints WidgetAdd siblings as disjoint Add new disjoint Remove disjoint siblingsList of disjoint classes18Make Classes Disjoint1.Select the Pizza class You will notice that the disjoints widget is empty2.

11、Click the“Add all siblings”buttonThe“Add siblings to disjoints dialog pops up3.Select the“Mutually between all siblings”option and OKPizzaTopping and PizzaBase appear in the disjoints widget4.Select the PizzaTopping classPizza and PizzaBase are already in the disjoints widget5.Note that the same app

12、lies for PizzaBaseStart with your existing ontology19Save Your Work1.Select File Save A dialog(as shown)will pop up2.Select a file using a file selector by clicking the button on the top rightYou will notice that there are 2 files created.pprj the project filethis just stores information about the G

13、UIand the workspace.owl the OWL filethis is where your ontology is stored inRDF/OWL format 3.Select OKOWL=easy to make mistakes save regularly20Create PizzaToppings1.Create subclasses of PizzaTopping:CheeseToppingVegetableToppingMeatTopping2.Make these subclasses all disjoint from one another(rememb

14、er to chose“Mutually between all siblings”when prompted)3.Create subclasses of CheeseTopping:MozzarellaTopping,ParmesanTopping4.Make these subclasses all disjoint from one another5.Create subclasses of VegetableTopping and make them disjoint:TomatoTopping,MushroomTopping6.Save the new file using Fil

15、e SaveStart with your existing ontology21What have we got?nWeve created a tree of disjoint classesnDisjoints are inherited down the treee.g.something that is a TomatoTopping cannot be a Pizza because its superclass,PizzaTopping,is disjoint from PizzanYou should now be able to select every class(exce

16、pt DomainConcept)and see its siblings in the disjoints widget22What are we missing?nThis is not a semantically rich modelnApart from“is kind of”and“is not kind of”,we currently dont have any other information of interestnWe want to say more about Pizza individuals,such as their relationship with oth

17、er individualsnWe can do this with propertiesPizzaPizzaTopping=individual23Properties Tab24Properties Tab:Property BrowserProperties can be in a hierarchySearch for propertySuperProperties of the current selected25Properties Tab:Property Browsernot used today:-New Datatype Property(String,int etc)Ne

18、w Object Property:Associates an individual to another individualDelete Property-New Annotation Properties for metadata-New SubProperty ie create“under”the current selection26Create a Property1.Switch to the Properties tab There are currently no properties,so the list is blank2.Create a new Object pr

19、operty using the button in the property browser3.Call the new Property“hasTopping”4.Create another Object Property called“hasBase”5.SaveStart with your existing ontology27Associating Properties with ClassesnWe now have two properties we want to use to describe Pizza individuals.nTo do this,we must g

20、o back to the Pizza class and add some further informationnThis comes in the form of Restrictions(which are a type of Condition)28ClassesTab:Conditions WidgetConditions asserted by the ontology engineerDefinition of the class(later)Description of the classConditions inherited from superclassesAdd di

21、fferent types of condition29Create a Restriction1.Switch to the OWL Classes tab2.Select PizzaNotice that the conditions widget only contains one item,DomainConcept with a Class icon.Superclasses show up in the conditions widget in this way3.Click the“Create Restriction”buttonA dialog pops up that we

22、 will investigate in a minute4.Select“hasBase”from the Restricted Property pane5.Leave the Restriction type as“someValuesFrom”6.Type“PizzaBase”in the Filler expression editor,then Click OKA restriction has been added to the Conditions widgetStart with your existing ontology30What does this mean?nWe

23、have created a restriction:hasBase.PizzaBaseon Class Pizza as a necessary condition“If an individual is a member of this class,it is necessary that it has at least one hasBase relationship with an individual from the class PizzaBase”PizzaPizzaBasehasBasehasBasehasBasehasBase“Every individual of the

24、Pizza class must have at least one base from the class PizzaBase”31What does this mean?nWe have created a restriction:hasBase PizzaBaseon Class Pizza as a necessary conditionPizzaPizzaBasehasBasehasBasehasBasehasBase“There can be no individual,that is a member of this class,that does not have at lea

25、st one hasBase relationship with an individual from the class PizzaBase”32Restrictions PopupRestriction TypeRestricted PropertyFiller ExpressionSyntax checkExpressionConstructPalette33Restriction Types Existential,someValuesFrom“Some”,“At least one”Universal,allValuesFrom“Only”hasValue“equals x”Card

26、inality“Exactly n”Max Cardinality“At most n”Min Cardinality“At least n”34Another Existential Restriction1.Make sure Pizza is selected2.Create a new Existential(SomeValuesFrom)Restriction with the hasTopping property and a filler of PizzaToppingWhen entering the filler,you have 2 shortcut methods rat

27、her than typing the entire classname:1)enter a partial name and use Tab to autocomplete2)use the select Class button on the editor paletteStart with your existing ontology35Create a Universal Restriction1.Create 2 disjoint subclasses of PizzaBasecalled“ThinAndCrispy”and“DeepPan”2.Create a subclass o

28、f Pizza called“RealItalianPizza”3.Create a new Universal(AllValuesFrom)Restriction on RealItalianPizza with the hasBase property and a filler of ThinAndCrispyStart with your existing ontology36What does this mean?nWe have created a restriction:hasBase.ThinAndCrispyon Class RealItalianPizza as a nece

29、ssary condition“If an individual is a member of this class,it is necessary that it must only have a hasBase relationship with an individual from the class ThinAndCrispy”RealItalianPizzaThinAndCrispyhasBasehasBasehasBasehasBase37What does this mean?nWe have created a restriction:hasBase.ThinAndCrispy

30、on Class RealItalianPizza as a necessary conditionDeepPanRealItalianPizzaThinAndCrispyhasBasehasBasehasBasehasBase“No individual of the RealItalianPizza class can have a base from a class other than ThinAndCrispy”hasBase38Universal Warning Trivial SatisfactionnIf we had not already inherited:hasBase

31、.PizzaBasefrom Class Pizza the following could holdRealItalianPizzaThinAndCrispyhasBasehasBasehasBasehasBase“If an individual is a member of this class,it is necessary that it must only have a hasBase relationship with an individual from the class ThinAndCrispy,or no hasBase relationship at all”Triv

32、ially satisfiedby this individualI.e.,Universal Restrictions by themselves do not state“at least one”39SummaryYou should now be able to:nidentify components of the Protg-OWL Interfacencreate Primitive Classesncreate Propertiesncreate some basic Restrictions on a Class using Existential and Universal

33、 qualifiers40More exercises:Create a MargheritaPizza1.Create a subclass of Pizza called NamedPizza2.Create a subclass of NamedPizza called MargheritaPizza3.Create a restriction to say that:“Every MargheritaPizza must have at least one topping from TomatoTopping”4.Create another restriction to say th

34、at:“Every MargheritaPizza must have at least one topping from MozzarellaTopping”Start with your existing ontology41Protg Tutorial:OverviewnSession 1:Interface basicsnSession 2:Defining a vegetarian pizza42Session 2:Vegetarian Pizza nIssue:Primitive Classes&PolyhierarchiesnAdvanced:ReasoningnAdvanced

35、:Creating Defined ClassesnUnion Classes:Covering AxiomsnExample:Creating a Vegetarian PizzanIssue:Open World AssumptionnUnion Classes:Closure43Loading OWL files from scratch1.If youve only got anOWL file:Select“OWL Files”as theProject Format,then“Build”to select the.owl file2.If youve got a valid pr

36、oject file*:Select“OWL Files”as the Project Format,and then“Open Other”to find the.pprj file(if youve already opened it,it will be in“Open Recent”)3.Open C:Program FilesProtege_3.3.1firstFewClasses.owl4.*ie one created on this version of Protg-the s/w gets updated once every few days,so dont count o

37、n it unless youve created it recently safest to build from the.owl file if in doubtRun Protg.exe44PolyhierarchiesnBy the end of this tutorial we intent to create a VegetarianPizzanSome of our existing Pizzas should be types of VegetarianPizzanHowever,they could also be types of SpicyPizza or CheeseL

38、oversPizzanWe need to be able to give them multiple parents47Vegetarian Pizza attempt 11.Create a new pizza called“VegetarianPizza”under Pizzamake this disjoint from its siblings as we have been doing2.Select MargheritaPizzayou will notice that it only has a single parent,NamedPizza3.Add VegetarianP

39、izza as a new parent using the conditions widget“Add Named Class”buttonnotice that MargheritaPizza now occurs in 2 places in the hierarchywe have asserted that MargheritaPizza has 2 parents48ReasoningnWed like to be able to check the logical consistency of our modelnWed also like to make automatic i

40、nferences about the subsumption hierarchy.A process known as classifyingqi.e.Moving classes around in the hierarchy based on their logical definitionnGeneric software capable of these tasks are known as reasoners(although you may hear them being referred to as Classifiers)nRACER,Pellet are reasoners

41、49Running PelletRun“pellet dig”A cmd window will open,pellet is now ready for use as an http server using a standard interface called DIG52Running PelletnYou can set the reasoner URL from Preferences setting53ClassifyingClassify taxonomy(and check consistency)Just check consistency (for efficiency)C

42、ompute inferred types (for individuals)54Reasoning about our Pizzas1.Classify your ontologyYou will see an inferred hierarchy appear,which willshow any movement of classes in the hierarchyYou will also see a results window appear at the bottom of the screen which describes the results of the reasone

43、rMargheritaPizza turns out to be inconsistent why?55Why is MargheritaPizza inconsistent?nWe are asserting that a MargheritaPizza is a subclass of two classes we have stated are disjointnThe disjoint means nothing can be a NamedPizza and a VegetarianPizza at the same timenThis means that the class of

44、 MargheritaPizzas can never contain any individualsnThe class is therefore inconsistent56Attempting again1.Close the inferred hierarchyand classification results pane 2.Remove the disjoint between VegetarianPizza and its siblingsWhen prompted,choose to remove only between this class and its siblings

45、3.Re-Classify your ontologyThis should now be accepted by the reasoner with no inconsistenciesStart with your current ontology57Asserted PolyhierarchiesnWe believe asserting polyhierarchies is badlet the reasoner do it!We lose some encapsulation of knowledgeDifficult to maintain58Defined ClassesnHav

46、e a definition.That is at least one Necessary and Sufficient conditionnAre marked in orange in the interfacenClasses,all of whose individuals satisfy this definition,can be inferred to be subclassesnReasoners can perform this inference59Describing a MeatyPizza1.Create a subclass of Pizza called Meat

47、yPizzaDont put in the disjoints or youll get the same problems as beforeIn general,defined classes are not disjoint2.Add a restriction to say:“Every MeatyPizza must have at least one meat topping”3.Classify your ontologyWhat happens?60Defining a MeatyPizza1.Click and drag your hasTopping.MeatTopping

48、 restriction from“Necessary”to“Necessary&Sufficient”The MeatyPizza class now turns orange,denoting that it is now a defined class2.Click and drag the Pizza Superclass from“Necessary”to “Necessary&Sufficient”Make sure when you release you are on top of the existing restriction otherwise you will get

49、2 sets of conditions.You should have a single orangeicon on the right stretching acrossboth conditions like this3.Classify your ontologyWhat happens?61Reasoner ClassificationnThe reasoner has been able to infer that anything that is a Pizza that has at least one topping from MeatTopping is a MeatyPi

50、zzaTherefore,classes fitting this definition are found to be subclasses of MeatyPizza,or are subsumed by MeatyPizzaThe inferred hierarchy is updated to reflect this and moved classes are highlighted in blue62How do we Define a Vegetarian Pizza?nNastynDefine in words?q“a pizza with only vegetarian to