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| - | ====== Reasoning with Ontologies ====== | ||
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| - | ^ Last verification: | 20160924 | | ||
| - | ^ Tools required for this lab: | [[http://protege.stanford.edu/products.php#desktop-protege|Protégé Desktop 5.0]] | | ||
| - | ^ ::: | [[http://semanticweb.org/wiki/Pellet|Pellet 2.3.1]] ({{http://home.agh.edu.pl/~kkutt/semweb/pellet-2.3.1.zip|pellet-2.3.1.zip}}) | | ||
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| - | ===== Introduction ===== | ||
| - | * Lecture: {{..:..:2015:eis2015semweb-ontology-logic.pdf|Ontology engineering and reasoning in Semantic Web}} (2015) | ||
| - | * [[#if_you_want_to_know_more|If you want to know more...]] | ||
| - | |||
| - | * OWL is based on Description Logics formalism -- if you want to know more about it, you can familiarize yourself with optional [[desc-logic|Intro to Description Logics]] lab. | ||
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| - | ===== Lab instructions ===== | ||
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| - | ==== - TBox and ABox [10 minutes] ==== | ||
| - | |||
| - | * The knowledge base in OWL (which is based on Description Logics) consists of two types of concepts: | ||
| - | * TBox - terminology, intensional representation | ||
| - | * ABox - assertions about individuals, extensional representation | ||
| - | * [[http://www.mkbergman.com/489/ontology-best-practices-for-data-driven-applications-part-2/|Why should we care about keeping them split?]] | ||
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| - | * 8-) Let's check if you understand this difference properly: Take your [[ontologies|casting agency ontology from WebProtégé lab]] or [[owl|multimedia ontology from Protégé lab]]. Identify which statements belong to Terminology (TBox) and World Description (ABox). Put them in the report divided into two sections: TBox and ABox (5 statements for each section). | ||
| - | |||
| - | ==== - OWL Reasoning - Class Inference [10 minutes] ==== | ||
| - | * In Description Logics on which the OWL language is based there are the following reasoning tasks for classes (terminology, TBox): | ||
| - | - Class subsumption (Structuring the knowledge base) | ||
| - | - Class equivalence (Are two classes in fact the same class?) | ||
| - | - Class disjointness (Do classes A and B have common members?) | ||
| - | - Class consistency (Isn't class A empty?) | ||
| - | |||
| - | - Model the following ontology axioms in Protege:<code> | ||
| - | Class: bus_driver | ||
| - | EquivalentTo: | ||
| - | person | ||
| - | that drives some bus | ||
| - | |||
| - | Class: driver | ||
| - | EquivalentTo: | ||
| - | person | ||
| - | that drives some vehicle | ||
| - | |||
| - | Class: bus | ||
| - | SubClassOf: | ||
| - | vehicle | ||
| - | </code> \\ Hints: | ||
| - | - To build the first axiom: | ||
| - | - Create appropriate classes \\ {{.:..:..:protege-reasoning1.png?w200|}} \\ | ||
| - | - and ObjectProperties: \\ {{.:..:..:protege-reasoning2.png?w200|}} \\ | ||
| - | - Define the BusDriver class with ''Equivalent classes'' button \\ {{.:..:..:protege-reasoning3.png?w200|}} | ||
| - | - Build the second axiom analogously: \\ {{.:..:..:protege-reasoning4.png?w200|}} \\ | ||
| - | - Build the third axiom using the ''SubClass of'' button: \\ {{.:..:..:protege-reasoning5.png?w200|}} \\ | ||
| - | - Start the reasoner (''Reasoner -> start reasoner'') and observe the inferred class hierarchy. What conclusions have been drawn? \\ {{.:..:..:protege-reasoning6.png?w200|}} \\ | ||
| - | - 8-) Include the modified ontology in the report. | ||
| - | - 8-) Explain the inferred relations and conclusions. | ||
| - | - Analyze the reasoning examples given [[http://mowl-power.cs.man.ac.uk/2009/07/sssw/people.html#people-class|here]] in "Class Inferences" section. | ||
| - | |||
| - | ==== - OWL Reasoning - Instance Inferences [10 minutes] ==== | ||
| - | * In Description Logics on which the OWL language is based there are the following reasoning tasks for instances (world description, ABox): | ||
| - | - Class membership (is instance //a// contained in class //C//?) | ||
| - | - Instance retrieval (find all (known) individuals belonging to a given class) | ||
| - | * and for the whole Knowledge Base (ABox+TBox): | ||
| - | - Global consistency of a knowledge base (Is the knowledge base meaningful?) | ||
| - | |||
| - | - Download the {{http://home.agh.edu.pl/~kkutt/semweb/people-prep.owl|pre-prepared ontology}} and load it in Protege (**NB:** the ontology classes and those on screenshots may differ a little). | ||
| - | - Model the following ontology axioms in Protege:<code> | ||
| - | Individual: Daily_Mirror | ||
| - | Types: | ||
| - | owl:Thing | ||
| - | |||
| - | Individual: Q123ABC | ||
| - | Types: | ||
| - | van, | ||
| - | white_thing | ||
| - | |||
| - | Individual: Mick | ||
| - | Types: | ||
| - | man | ||
| - | Facts: | ||
| - | reads Daily_Mirror, | ||
| - | drives Q123ABC | ||
| - | |||
| - | Class: white_van_man | ||
| - | EquivalentTo: | ||
| - | man | ||
| - | that drives some (van | ||
| - | and white_thing) | ||
| - | SubClassOf: | ||
| - | reads only tabloid | ||
| - | </code> \\ //For those not familiar with UK culture, White Van Man is a stereotype used to describe a particular kind of driver. [[http://en.wikipedia.org/wiki/White_van_man|Wikipedia]] provides an entry with some additional information and references.// \\ Hints: | ||
| - | - Create appropriate instances in ''Individuals'' tab \\ {{.:..:..:protege-reasoning7.png?w200|}} | ||
| - | - If the instance is of 2 types, create it only once and then add the second type: \\ {{.:..:..:protege-reasoning8.png?w200|}} | ||
| - | - Add object properties to connect individuals: \\ {{.:..:..:protege-reasoning9.png?w200|}} | ||
| - | - Define the class: \\ {{.:..:..:protege-reasoning10.png?w200|}} | ||
| - | - Start the reasoner (''Reasoner -> start reasoner'') and observe the inferred class hierarchy. Where is the ''white_van_man''? What conclusions have been drawn? | ||
| - | - 8-) Include the modified ontology in the report. | ||
| - | - 8-) Explain the inferred relations and conclusions. | ||
| - | - Analyze the reasoning examples given [[http://mowl-power.cs.man.ac.uk/2009/07/sssw/people.html#people-instance|here]] in "Instance Inferences" section. | ||
| - | |||
| - | ==== - OWL Reasoning - Reasoners [5 minutes] ==== | ||
| - | DL reasoners may be integrated with other tools - as in the case of Protege presented before - as well as run independently via various interfaces. Popular DL reasoners include: FaCT++, Pellet, HermiT, RacerPro and many others. | ||
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| - | We will use the <wrap download><wrap caution>{{http://home.agh.edu.pl/~kkutt/semweb/pellet-2.3.1.zip|Pellet}}</wrap></wrap> reasoner. | ||
| - | - Unpack the zip. | ||
| - | - Run ''pellet.sh help'' to get familiar with available commands. | ||
| - | - Try ''pellet.sh consistency <ontology>'' where the ''<ontology>'' is: | ||
| - | - Your ontology from [[.:owl|previous lab]] | ||
| - | - ''people+pets.owl'' ontology provided with Pellet in ''examples/data/'' directory \\ and observe the results. | ||
| - | - Try ''pellet.sh classify <ontology>'' with the two above mentioned ontologies and observe the results. | ||
| - | - 8-) What are the results? Write them down or provide a screenshot of the answer in the report. | ||
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| - | ==== - Advanced OWL reasoning [50 minutes] ==== | ||
| - | These instructions are based on the [[http://www.cs.man.ac.uk/~stevensr/menupages/fhkb.php|The Family History Knowledge Base Tutorial]] by The University of Manchester, School of Computer Science | ||
| - | |||
| - | - Download the {{.:..:..:ontologies.zip|}} pack. | ||
| - | - Open Protege (type ''protege'' in command line on lab316 laptop). | ||
| - | |||
| - | === - Warm up === | ||
| - | - Open (''Family-tree-0.owl'') | ||
| - | - It contains ''Sex'', ''Female'', ''Male'', ''Person'', ''Man'' and ''Woman'' Classes. | ||
| - | - Create ''hasSex'' property, Set domain and ranges on ''hasSex'' (Person/Sex), make it //functional//. | ||
| - | - Create restrictions on ''Person'' ''hasSex some Sex''. | ||
| - | - Make Man and Woman **defined** (use ''Equivalent classes''): ''Man EquivalentTo Person that hasSex some Male'' etc. \\ {{.:..:..:owl-man.png?180|}} | ||
| - | - Import plain-individuals, observe that none of them have any assertions on them. (''Active Ontology'' tab -> ''Imported ontologies'' -> ''Direct imports''). | ||
| - | - Choose an individual, add ''Types'': ''Person and (hasSex some Male)'' \\ {{.:..:..:owl-robert-individual.png?300|}} | ||
| - | - Using the ''Reasoner'' menu in Protege (''Reasoner -> Start/Synchronize reasoner''), classify the ontology. What inferences are made? Write them in the report 8-) | ||
| - | |||
| - | === - Characteristics of properties === | ||
| - | - Close the previous ontology. Load ''Family-tree-1.owl''. Check how ''Man'' and ''Woman'' classes are defined. | ||
| - | - Create object properties: ''hasFather'', ''hasMother'', make them //functional//, add //domain// and //range//: ''Person'', ''Man/Woman'', add //inverse properties//: \\ {{.:..:..:owl-hasmother.png?200|}} | ||
| - | - Create restrictions on Person: ''has Mother some Woman'', ''hasFather some Man'' \\ {{.:..:..:owl-hasparents.png?200|}} | ||
| - | - Load ''individuals-1-parantage.owl'' file. | ||
| - | - Classify the ontology. What inferences are made? Write them in the report 8-) | ||
| - | |||
| - | |||
| - | === - Datatype properties === | ||
| - | - Close the previous ontology. Load ''Family-tree-2.owl''. | ||
| - | - Create or find datatype properties: ''birthYear'', ''deathYear'', make them //functional//. \\ {{.:..:..:owl-datatypes.png?200|}} | ||
| - | - Create ''Victorian'' class: ''Person and birthYear some integer[>=1837, <=1901]'' | ||
| - | - Classify the ontology. How many individuals have been classified as Victorians? 8-) | ||
| - | |||
| - | === - Transitive properties === | ||
| - | - Close the previous ontology. Load ''Family-tree-3.owl''. | ||
| - | - Create a new super-property of ''hasParent'' called ''hasAncestor'', | ||
| - | - Make it transitive and create inverse property. | ||
| - | - Clasify, look at property hierarchy. What do we know about Robert? 8-) | ||
| - | - Close the previous ontology. Load ''Family-tree-4.owl''. | ||
| - | - Model the information about David: \\ {{.:..:..:owl-david.png?300|}} | ||
| - | - Classify the ontology. Answer the questions: | ||
| - | - What type does David_bright_1934 have? 8-) | ||
| - | - How many children does he have? 8-) | ||
| - | |||
| - | === - Property chains === | ||
| - | - Close the previous ontology. Load Family-tree-5.owl. | ||
| - | - Add hasGrandParent sub prop of hasAncestor (inverse grandparentOf) | ||
| - | - Add domain and ranges | ||
| - | - Add sub properties ''hasGrandMother/Father'' + domains and ranges | ||
| - | - Add property chain ''hasParent o hasFather/Mother -> hasGrandFather/Mother'' \\ {{.:..:..:owl-grandpa.png?300|}} | ||
| - | - Classify the ontology. What do we learn about Robert? 8-) | ||
| - | |||
| - | === - Classes with Individuals, Open World Assumption === | ||
| - | - Close the previous ontology. Load Family-tree-6.owl. | ||
| - | - Make class of all ancestors and class of robert's ancestors. \\ {{.:..:..:owl-class-individuals.png?400|}} | ||
| - | - Classify. What are the results? | ||
| - | - Make class of people with min 3 children. | ||
| - | - Classify the ontology, do we find parents with 3 children? Why? 8-) | ||
| - | - How to really find parents that have 3 children? 8-) | ||
| - | - How to make individuals different from each other? 8-) | ||
| - | ===== If you want to know more ===== | ||
| - | |||
| - | OWL Tutorials: | ||
| - | * http://www.cs.man.ac.uk/~horrocks/ISWC2003/Tutorial/ | ||
| - | * http://mowl-power.cs.man.ac.uk/2009/07/sssw/ | ||
| - | * http://mowl-power.cs.man.ac.uk/2008/iswc-tones/ | ||
| - | * http://owl.cs.manchester.ac.uk/publications/talks-and-tutorials/ | ||
| - | * http://protege.stanford.edu/conference/2009/tutorials.html | ||
| - | * http://www.linkeddatatools.com/introducing-rdfs-owl | ||
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