•11st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester1Protégé-OWL TutorialSession 1: Primitive ClassesNick Drummond1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester2This session► Review: OWL Basics► Intro: Protégé-OWL► Interface: Creating Classes► Tools: The Reasoner► Concept: Disjointness► Interface: Creating Properties► Concept: Describing Classes► Interface: Creating Restrictions1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester3Review of OWL (30 secs)OWL…► is a W3C standard – Web Ontology Language► comes in 3 flavours (lite, DL and full)► we are using OWL DL (Description Logic)► DL = decidable fragment of First Order Logic (FOL)► is generally found in XML/RDF syntax► is therefore not much fun to write by handSo, we have tools to help us1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester4Starting Protégé-OWL1. Select “OWL Files”2. Select “New”Run Protégé from Start Menu•21st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester5Protégé OWL pluginProtégé tabs1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester6Protégé OWL plugin: TabsUsed in this tutorialChanging the GUIPopulating the modelTop-level functionalityExtensions (visualisation)1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester7Classes Tab1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester8Classes Tab: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 class•31st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester9Classes Tab: Class Editor1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester10Classes Tab: Class EditorClass annotations (for class metadata)Class name and documentationProperties “available” to ClassDisjoints widgetConditions WidgetClass-specific tools (find usage etc)1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester11Create a Class Hierarchy1. Click the “Create Class” button(this is above the class hierarchy)A new class will be created as a subclass of owl:Thing2. Type in a new name “DomainConcept” over the default(return updates the hierarchy)3. Create another class called “Pizza” using the same methodYou will notice that Pizza has been created as a subclass of DomainConcept as this was the class selected when the button was pressed. You can also right-click any class and select “Create Class”4. Create two more subclasses of DomainConcept “PizzaTopping” and “PizzaBase”.Any mistakes, use the “Delete Class” button next to “Create Class”5. Create subclasses of PizzaTopping: CheeseTopping, VegetableTopping and MeatToppingStart with your empty ontology1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester12Save Your Work1. Select File ÆSaveA dialog (as shown) will pop up2. Select a file using a file selector by clicking the button on the top rightYou will notice that 2 files are created.pprj – the project filethis just stores information about the GUIand the workspace.owl – the OWL filethis is where your ontology is stored inRDF/OWL format3. Select OKOWL = easy to make mistakes – save regularly•41st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester13Create an odd PizzaTopping1. Create a subclass of VegetableToppingcalled “MeatyVegetableTopping”You will notice that the Conditions Widget has VegetableToppinglisted – this means it is an asserted superclass of MeatyVegetableTopping2. Add MeatTopping as another parent of MeatyVegetableTopping using the “Add Named Class” button on theconditions widgetMeatyVegetableTopping can now beseen underneath both parents in theasserted class hierarchyWe have asserted that MeatyVegetableToppinghas 2 parentsStart with your existing ontology1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester14Reasoning► We’ve just created a class that doesn’t really make sense –what is a Meaty Vegetable Topping?► We’d like to be able to check the logical consistency of our model► Later we’d also like to make automatic inferences about the subsumption hierarchy. A process known as classifying► ie Moving classes around in the hierarchy based on their logical definition► Generic software capable of these tasks are known as reasoners (although you may hear them being referred to as Classifiers)► RACER is a reasoner1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester15Running Racer1. Run racer.exe from wherever it was installedA cmd window will open and two “service enabled” messages will appear in the ouputRacer is now ready for use as an http server using a standard interface called DIGNB. Alternative DIG reasoners like FaCT can also be used1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester16Accessing the ReasonerClassify taxonomy(and check consistency)Just check consistency(for efficiency)Compute inferred types(for individuals)•51st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester17Reasoning about our Pizzas1. Classify your ontologyWe could just use the “Check Consistency”button but we’ll get into the habit of doing afull classification as we’ll be doing this laterThe reasoner dialog will pop up while thereasoner works2. When the reasoner has finished,press OKYou will see an inferred hierarchy appear,which will show any movement of classes in the hierarchyIf the reasoner has inferred anything about our model, this is reported in the reasoner dialog and in a seperate results window.Not much appears to have happened – why has the reasoner not picked up on this odd class?Start with your existing ontology1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester18Disjointness► OWL assumes that classes overlapMeatToppingVegetableTopping= individual► This means an individual could be both a MeatTopping and a VegetableTopping at the same time► We want to state this is not the case1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester19Disjointness► If we state that classes are disjointMeatToppingVegetableTopping= individual► This means an individual cannot be both a MeatTopping and a VegetableTopping at the same time► We must do this explicitly in the interface1st Feb 2005Protege-OWL tutorial, © 2005 Univ. of Manchester20ClassesTab: Disjoints WidgetAdd siblings as disjointAdd new disjoint Remove disjoint siblingsList
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