Presentation on theme: "Ontologizing the Ontolog Content"— Presentation transcript:
1 Ontologizing the Ontolog Content Protégé WorkshopDenise A. D. Bedford, Ph.d.July 23, 2006
2 TaxoThesaurus Background 2Ontolog TaxoThesaurus Working Group aims to:Establish a framework for developing an ontology that will focus on the current and future content of the Ontolog community, support a range of uses of the Ontolog and Ontolog-referenced content, by Ontolog members and non-membersProvide a sustainable foundation for future variations in content, use and users - which is extensible without radical re-engineering going forwardProvide a framework against which a basic set of functional architecture requirements can be defined – June discussionProvide a framework against which various semantic technologies might be positioned to support Ontolog - April and June discussions
3 TaxoThesaurus Background 3Provide a basis for a case study in collaborative practice domain ontology development and managementProvide a comparison – along the way – of the various ontology reference modelsIf the group wishes – along the way – provide the community with guidance in positioning semantic solutions vis a vis semantic problems
4 Goal is not to…4Advocate one particular semantic approach over others because they all serve different purposesProvide a survey of or evaluate the individual technologies on the market todaySuggest that any one person has a solution that works for everyone
5 Presentation Overview Description of the Bottom Up StrategyStatus Update on the Ontolog Ontologizing WorkExpert Review and Evaluation of Ontolog Outputs (Workshop begins with this step…)Discussion of Next Steps and Invitation to Participate
7 Workshop OverviewStep 1. Describe the domain by brainstorming use, users and content to be ontologizedStep 2. Identify the parameters of the ontology and describe their behaviorStep 3. Identify semantic methods to support individual parametersStep 4. Take stock of architectural considerationsStep 5. Generate values for the ontology parametersStep 6. Coordinate review and validation of ontology valuesStep 7. Operationalize ontology
8 Ontology Value Chain Content, Use, Users Definitions of Entities, DescribeDomainOntologyParametersArchitectureIssuesSemanticMethodsGenerateValuesExpertReviewOperationalizeOntologyContent,Use, UsersDefinitions ofEntities,AttributesClasses,RelationshipsApplicationRequirementsStrategy forGeneratingValuesOntologyRaw ValueCreationOntologyRefinedValueCreationWorkingOntology
10 Describing the DomainOntologies may involve semantic analysis, technologies, architecture, categorization, concept mapping and so forthUltimately, though, they are about describing a domain so we should always begin with a general definition of the domainDomain may be a line of business or what we typically consider a subject domainToday we’ll work with the domain of ontologies - we will recognize very quickly that defining the domain is not easy and we will not agree on the definition until we have worked through several additional steps
11 Ontolog DomainWe have focused the TaxoThesaurus project on the domain of ontologies since we have subject matter experts to work with and since we only have a few hours to walk through this exerciseWe will also take a bit of a shortcut and use the same boundaries to define our Ontology domain as are used to define the Ontolog Community of Practice
12 Describing the Domain12As a starting point, let’s work with framework which contains three essential components that will help us to better describe our domain:Domain ContentUsersUse/processesThese basic reference points should help us to identify several scenarios and to understand the basic functional requirements our ontology will have to satisfy
13 The Context for an Ontolog Ontology 13UsersUse or FunctionContextInformation (Document)
14 Users14May seem like the easiest dimension to address – but we need to make sure we have the same goals for the Ontolog ontologyDo we assume that only Ontolog active members will be served by the ontology?Or, do we support all members and the general public who might be interested in joining the community or who might find the wiki content a valuable resource for learning?Are we assuming only ontolog-sophisticates or do we include general managers, novices, general public interest?
15 User Community Who Domain Knowledge Roles Ontolog Member Wiki 15WhoDomain KnowledgeRolesOntolog MemberWikiWiki ManagerOntolog Member/Non-MemberOntology research & developmentResearchers, discussants, presenters, novicesComputational linguisticsStandards development workParticipants, vendors, observers, implementorsMetadataCreators, users, semantics developers, computational linguistsTaxonomiesCreators, designers, users, semantics developers, computational linguistsInformation ArchitectureEngineers, information scientistsSemantic TechnologiesDevelopers, users, implementors, linguists, novices
16 Use and Context16It is challenging for people who are so familiar with ontology development and semantic technologies to step back and think about how an ontology would actually support our use of the Ontolog contentBut, this is a critical first step – without understanding the use and context, we cannot establish a baseline ontologyWithout understanding use and context we will forever argue about which model works best, which tools work best and who should do what – actually, there is room for variation and negotiation hereFollowing tables are the result of some brainstorming and observations from the Ontolog community itself
17 Possible Uses of Ontolog Content 17DoingWhatFindPerson who knows something about an issueBrowseIssues that Ontolog has discussedAll people who participated in a discussionLearn AboutReference models discussed by OntologGet list ofProblems Ontolog identified that need attentionCollections by topicSearchFuture conference call topics
18 Possible Uses of Ontolog Content 18DoingWhatSearchNext scheduled callSpecific messageFindList of all members of OntologSpecific Ontolog memberReference to ontology standardsBook referencesOrganizations working in this area
19 Possible Uses of Ontolog Content 19DoingWhatFindUpcoming conferences & participantsGenerateKnowledge map of who knows what in OntologiesMap of the social networking in OntologPublishreview of a new bookStartDiscussion of a new topicAnnotate/summarizeDiscussion threadOthers??
20 Content20In order to understand the content the Taxo-Thesaurus Project Team ran an inventory of all the content published to or contained in the WikiThe Ontolog Use Case surfaced over 65,000 content objects (some of which were versions of the same object)The inventory gave us a better sense of the kinds of content available in the domain and an accurate picture of what was covered in the existing repositoryWe discovered that not all of the kinds of content that belong to the broader domain of Ontologies are accessible in or from the Wiki, though.This includes people, organizations, as well as other kinds of static information contentWe need to add content to the domain
22 First Cut at Ontolog Content 22Ontolog People profiles/pagesOntolog presentationsOntolog discussion threadsOntolog conceptsOntolog Activity CalendarOntolog Conference call notesOntolog Conference call agendasOntolog Conference call minutesOntolog Conference call transcriptsmessagesDiscussion threads/forumsProfessional Conference schedules & announcementsProfessional Conference representationBooks on ontology topicsPublished articles on ontology topicsReviews of books on ontologiesOntology standardsProfessional organizationsResearch institutionsWiki search logs
23 Describing the DomainAt the end of this Step we have a basic idea of what kinds of content the ontology will have to cover, the kinds of entities it will have to include, and the kinds of relationships and concepts that will be needed to support functionalityWe are now ready to begin to specify the parameters of the ontology
24 Step 2. Identify the Parameters of the Ontology
25 Definition of Ontology “Data model that represents a domain and is used to reason about the objects in that domain and the relationships between them. Ontologies are used in artificial intelligence, the semantic web, software engineering and information architecture as a form of knowledge representation about the world or some part of it. Ontologies generally describe:EntitiesClassesAttributesRelations”(source – Wikipedia)
26 Ontology Architecture Begins to Emerge 26usesContextualMatrix &SensiingUnderstood inBusinessRuleHasUseOntolog TopicClass SchemeHasMeaning inContentEntityDefinitionUserAuthority Control –Member NamesHasvaluesHas relationship toThesaurus ofOntolog ConceptsMetadataProfileHasHasHasusesContentElementsContentModelAreas of ExpertiseProfileHasAuthority Contro –OrganizationsHasvaluesContentElementsAggregationLevelsContainsContent
27 Entities in the Ontolog Domain Include… PeopleInstitutionsCommunities of PracticeJournal articlesBooksDiscussion threadsPresentationsStandardsProject proposalsMemoranda of UnderstandingConference announcementsConference presentationsResearch grant program descriptionsResearch reportsConference call notesConference call tapes…..many others
28 Attributes Include...Ideally, we would model all of these entities at least at a high levelThe models of these entities would include:Attributes of entities as structured content (structured data)Content elements (semi- or unstructured content)Value added metadata
29 More Advanced Entity Models When we began describing content about ten years ago, we went to a more granular levelWe defined data models for our entitiesIdeally, you will also take the effort to the entity data model levelFollowing is an example of a data model for a communiqueWe also defined data models for people, institutions, countries, projects, many types of knowledge, for document types, communications (drawing on news schema), etc.Taking it to this level enables you to apply the ontology at a more granular level and to increase the goodness of your application
30 Content Data Model Example – Event, Communique 30
31 In order for Ontolog to support…. SearchWe need to know the parameters users will search by (for who, what, where, when, how…)We need to understand the behavior and semantic challenges of those parameters (author names and variations, affiliations, facets of domains, dates, …)Knowledge mapping of Ontolog membersWe need to know who is a member of the Ontolog CoPWe need to know general areas of expertise in order to describe the mebers consistently knowledgeWe need to know their names and variations of their names,We need to know their affiliations (organizational names)
32 In order for Ontolog to support…. Navigation/browse by novices and expertsWe need to know how to organize the content for easy access. By domain facet? By topic? By country?How to organize facets to facilitate expert and novice access.How to maintain the reference sources that support facets.Easily access at the concept level by managers and others who may not have technical expertise…What we discovered when we did the inventory was that 90%+ of the Ontolog content is technical in natureOur expectation that non-technical managers would use the content to understand the value of ontologies does not hold nowWe need to include more non-technical content and we need to bridge the technical/non-technical vocabulary
33 Understanding Semantic Behavior of Attributes My experience suggests that before we can successfully apply semantic technologies in an ontology context, we need to understand the behavior of the attributesThere are many different kind of semantic methods and it is important to match the right solution to the problemLet’s think about some of the semantic challenges we find in some typical attributesPerson’s nameOrganization nameCountry nameClass schemeConcepts
34 People Name Challenges People names vary in different waysOver time as names change with life eventsDenise Ann DowdingDenise Ann Dowding BedfordIn their format depending on contextD. BedfordD. A. D. BedfordDenise D. BedfordDenise A. BedfordDenise A. D. BedfordCommon versus formal namesDenny vs. DeniseRaju vs. Rajendra vs. NatarajanNeed to link all semantic equivalents in the ontology
35 Class Schemes & Classification Problems Have inheritance structures which must be respectedClasses may experience scope changesClasses may appear or be archived over timeMay be insufficiently comprehensive in coverage of the domainClassificationHuman classification tends to suffer from inconsistencies due to limited perspectives, variations in perception, and variations over timeClasses need to be comprehensively represented across the domain and managed consistently over timeClassification needs to be performed consistently
36 Geographic Names Variations in country names occur Over time as political context changesArmeniaSoviet Socialist Republic of ArmeniaBy perspective and traditionNew Delhi or ChennaiMombay or BombayAll variations need to be linked as equivalencies or they need to be linked as predecessor/successor forms in an authority controlled context
37 Concept Challenges Primary challenges with concepts are based on: Concept as a word unit – as defined in dictionaries or word compendiums (WordNet)Girls, educationSediment, transportConcept as a multiword unit – idea as identified in glossaries, thesauriGirls educationSediment transportTrue concepts are defined at the multiword levelNeed to be able to understand the linguistic nature of the language in order to discover concepts
38 Quick Taxonomy PrimerBefore we can begin to model and/or solve semantic problems programmatically, we need to understand the structure and behavior of taxonomiesThere are five types of taxonomies:Flat taxonomies (controlled lists)Hierarchical taxonomies (class schemes)Ring taxonomies (synonym, equivalencies)Network taxonomies (thesauri, semantic networks)Faceted taxonomies (aspects, metadata)
39 Flat Taxonomy Structure Energy Environment Education Economics Transport Trade Labor Agriculture
40 Hierarchical Taxonomy A hierarchical taxonomy isrepresented as a tree datastructure in a databaseapplication. The tree datastructure consists of nodesand links. In an RDBMSenvironment, the relationshipsbecome associations. In ahierarchical taxonomy, a nodecan have only one parent.
41 Network TaxonomiesA network taxonomy is a plex data structure. Each node can have more than one parent. Any item in a plex structure can be linked to any other item. In plex structures, links can be meaningful & different.
42 Ring TaxonomyPoverty mitigationPoverty alleviationPoverty reducationPoverty eliminationPoverty preventionPoverty abatementPoverty reductionRings can include all kinds of synonyms - true, misspellings, predecessors, abbreviationsPoverty eradication
43 Facet Taxonomies Faceted taxonomy represented as a star data structure. Eachnode in the start structure isliked to the center focus.Any node can be linked toother nodes in other stars.Appears simple, but becomescomplex quickly.
45 Functional Architecture & Requirements The focus of the workshop is not to discuss the architecture to support an ontologyInstead, we simply highlight this step to emphasize the importance of stopping at this point in the process to focus on how you will support use of the ontologyThis is where varying assumptions may cause a breakdown in agreements within groupsSome may presume that an ontology will be applied on top of content dynamicallyOthers may presume that the ontology will be embedded into a more formal enterprise architecture
46 Functional Requirements Begin to Emerge 46At this stage functional requirements and architecture issues begin to surface. In the WB context, we realized we needed:Metadata schemaDifferent kinds of taxonomies (controlled lists, rings, hierarchies, concept networks)Semantic analysis tools to support metadata captureMetadata encoding options (xml, rdf, etc.)Metadata storage options (e.g. embedded in document, distinct database, etc.)Search system which supports attribute searching & which leverages reference sourcesBrowse structureReportingData mining and clusteringOther more sophisticated inference and reasoning options to support contextualization, business intelligence, and expert systems/inferencing engines and
48 Step 4. Identify Semantic Methods to Generate Ontology Values
49 Reality of Ontolgy Values Ontologies are grounded on structures, definitions, relationships and VALUESWithout VALUES you don’t have an ontologyThe problem is that generating values is very resource intense and no one has sufficient human resources to support this workSolution is to leverage semantic technologies to generate values for ontologiesAs we saw in Step 3, there are different kinds of semantic problems that require different kinds of solutionsChallenge is finding the right semantic solution to fit the semantic problem
50 Ontolog ValuesToday we will share with you for your review and critique some programmatically generated values for entities, attributes, concepts and reference sourcesBefore we do that, though, we’d like to describe how we used semantic technologies to generate the outputsBefore we describe the technologies and how we used them, though, it might be important to distinguish two basic types of approaches
51 NLP Technologies – Two Approaches Over the past 50 years, there have been two competing strategies in NLP - statistical vs. semanticIn the mid-1990’s at the AAAI Stanford Spring Workshops it was agreed by the active practitioners that the statistical NLP approach had hit a rubber ceiling – there were no further productivity gains to be made from this approachAbout that time, the semantic approach showed practical gains – we have been combining the two approaches since the late 1990’sTeragram supports both approaches but is a semantic technology at base – this is the best configuration and it provides the greatest flexibility.
52 Statistical NLPStatistical Approach uses statistical regression and Bayesian modeling methods to find patterns in words.This approach treats words as if they are ‘data’ – it breaks text down into single-word tokens and then tries to find similar tokens. There is no attempt to understand or detect meaning in the words – they are only characters/digits in strings.It then runs statistical analysis to find ‘co-occurring tokens’The problem with this approach is that it works only at the word or word fragment level and you never get to a higher level of understanding from this baseline.This approach helps you to learn that ‘girls’ and ‘education’ are related – but, we don’t need a statistical tool to tell us this – we already know this and can represent it as a concept (vs. a word)
53 Problem with Statistical NLP We experimented with several of these tools in the early 2000s – including Autonomy, Semio, Northern Lights ClusteringWe saw the following known effects --the statistical associations you generate are entirely dependent upon the frequency at which they occur in the training setWithout a semantic base you cannot distinguish types of entities, attributes, concepts or relationshipsIf the training set is not representative of your universe, your relationships will not be representative and you cannot generalize from the resultsIf the universe crosses domains, then the words that have the greatest commonality (least meaning) have the greatest association value
54 Semantic NLPFor years, people thought the semantic could not be achieved so they relied on statistical methodsThe reason they thought it would never be practical is that it took a long time to build the foundation – understanding human language is not a trivial exerciseBuilding a semantic foundation involves:developing grammatical and morphological rules – language by languageUsing parsers and Part of Speech (POS) taggers to semantically decompose text into semantic elementsBuilding dictionaries or corpa for individual languages as fuel for the semantic foundation to run onMaking it all work fast enough and in a resource efficient way to make it economically practical
56 Getting Semantic with Computational Linguistics Computational linguistics is an interdisciplinary field dealing with the logical modeling of natural language from a computational perspectiveComputational linguistics puts the semantic in natural language processing.Computational linguistics predates artificial intelligence - originated with efforts in the United States in the 1950s to have computers automatically translate texts in foreign languages into English, particularly Russian scientific journals.This work was finally brought to a practical level in the 1980s with the joint NASA-Russian Soyuz Space Station work. The first product we looked at in 1998 was NASA’s MAI toolsetIt has taken us 50 years to get where we are today – and Teragram provides us with some practical NLP capabilities.
57 How We Used the Semantic Technologies Teragram is a set of multilingual natural language processing (NLP) technologies that use the representation and meaning of text to distill relevant information from vast amounts of data.Teragram’s Natural Language Processing technologies include:Rules Based Concept Extraction (also called classifier)Grammar Based Concept ExtractionCategorizationSummarizationClusteringLanguage detectionThe package consists of a developers client (TK240) and multiple servers to support the technologiesWe have taken this basic ‘technology toolkit’ and implemented it in a way that supports programmatic metadata capture and is consistent with good practice data quality and data management
58 Rule Based Concept Extraction What is it?Rule based concept or entity extraction is a simple pattern recognition technique which looks for and extracts named entitiesEntities can be anything – but you have to have a comprehensive list of the names of the entities you’re looking forHow does it work?It is a simple pattern matching program which compares the list of entity names to what it finds in contentRegular expressions are used to match sets of strings that follow a pattern but contain some variationList of entity names can be built from scratch or using existing sources – we try to use existing sourcesA rule-based concept extractor would be fueled by a list such as Working Paper Series Names, edition or version statement, Publisher’s names, etc.Generally, concept extraction works on a “match” or “no match” approach – it matches or it doesn’tYour list of entity names has to be pretty good
59 Rule Based Concept Extraction How do we build it?Create a comprehensive list of the names of the entities – most of the time these already exist, and there may be multiple copiesReview the list, study the patterns in the names, and prune the listApply regular expressions to simplify the patterns in the namesBuild a Concept ProfileRun the concept profile against a test set of documents (not a training set because we build this from an authoritative list not through ‘discovery’)Review the results and refine the profileState of IndustryThe industry is very advanced – this type of work has been under development and deployed for at least three decades now. It is a bit more reliable than grammatical extraction, but it takes more time to build.
60 Rules Based Concept Extraction Examples Loan #Credit #Report #Trust Fund #ISBN, ISSNOrganization Name (companies, NGOs, IGOs, governmental organizations, etc.)AddressPhone NumbersSocial Security NumbersLibrary of Congress Class NumberDocument Object IdentifierURLsICSID Tribunal NumberEdition or version statementSeries NamePublisher NameLet’s look at the Teragram TK240 profiles for Organization Names, Edition Statements, and ISBN
61 ISBN Concept Extraction Profile – Regular Expressions (RegEx) Replace this slide with the ISBN screen – with the rulesdisplayedConcept based rules engine allows us to define patterns to capture other kinds of dataUse of concept extraction, regular expressions, and the rules engine to capture ISBNs.Regular expressions match sets of strings by pattern, so we don’t need to list every exact ISBN we’re looking for.
62 List of entities matches exact strings List of entities matches exact strings. This requires an exhaustive list– but gives us extensive control. (It would be difficult to distinguish by pattern between IGOs and other NGOs.)Classifier concept extraction allows us to look for exact string matches
63 Another list of entities matches exact strings Another list of entities matches exact strings. In this case, though, we’re making this into an ‘authority control list’– We’re matching multiple strings to the one approved output. (In this case, the AACR2-approved edition statement.)
64 Grammatical Concept Extractions What is it?A simple pattern matching algorithm which matches your specifications to the underlying grammatical entitiesFor example, you could define a grammar that describes a proper noun for people’s names or for sentence fragments that look like titlesHow does it work?This is also a pattern matching program but it uses computational linguistics knowledge of a language in order to identify the entities to extract – if you don’t have an underlying semantic engine, you can’t do this type of extractionThere is no authoritative list in this case – instead it uses parsers, part-of-speech tagging and grammatical codeThe semantic engine’s dictionary determines how well the extraction works – if you don’t have a good dictionary you won’t get good resultsThere needs to be a distinct semantic engine for each language you’re working with
65 Grammatical Concept Extractions How do we build it?Model the type of grammatical entity we want to extract and use the grammar definitions to build a profileTest the profile on a set of test content to see how it behavesRefine the grammarsDeploy the profileState of IndustryIt has taken decades to get the grammars for languages well definedThere are not too many of these tools available on the market today but we are pushing to have more open sourceTeragram now has grammars and semantic engines for 30 different languages commercially availableIFC has been working with ClearForestLet’s look at some examples of grammatical profiles – People’s Names, Noun Phrases, Verb Phrases, Book Titles
66 TK240 Grammars for People Names Grammar concept extraction allows us to define concepts based on semantic language patterns.
67 Grammatical Concept Extraction Proper Noun Profile for People Names uses grammars to find and extract the names of people referenced in the document.<?xml version="1.0" encoding="UTF-8"?><Proper_Noun_Concept><Source><Source_Type>file</Source_Type><Source_Name>W:/Concept Extraction/Media Monitoring Negative Training Set/ 001B950F2EE8D0B B4003FF816.txt</Source_Name></Source><Profile_Name>PEOPLE_ORG</Profile_Name><keywords>Abdul Salam Syed, Aruna Roy, Arundhati Roy, Arvind Kesarival, Bharat Dogra, Kwazulu Natal, Madhu Bhaduri, </keywords><keyword_count>7</keyword_count></Proper_Noun_Concept>
68 Grammatical Concept Extraction – People Names Client testing mode
69 Rule-Based Categorization What is it?Categorization is the process of grouping things based on characteristicsCategorization technologies classify documents into groups or collections of resourcesAn object is assigned to a category or schema class because it is ‘like’ the other resources in some wayCategories form part of a hierarchical structure when applied to such subjects as a taxonomyHow does it work?Automated categorization is an ‘inferencing’ task- meaning that we have to tell the tools what makes up a category and then how to decide whether something fits that category or notWe have to teach it to think like a human being –When I see -- access to phone lines, analog cellular systems, answer bid rate, answer seizure rate – I know this should be categorized as ‘telecommunications’We use domain vocabularies to create the category descriptions
70 Rule Based Categorization How do we build it?Build the hierarchy of categoriesManually if you have a scheme in place and maintained by peopleProgrammatically if you need to discover what the scheme should beBuild a training set of content category by category – from all kinds of contentDescribe each category in terms of its ‘ontology’ – in our case this means the concepts that describe it (generally between 1,000 and 10,000 concepts)Filter the list to discover groups of conceptsThe richer the definition, the better the categorization engine worksTest each category profile on the training setTest the category profile on a larger set that is outside the domainInsert the categirt profile into the profile for the larger hierarchyWe built the Ontolog classification scheme using the programmatic approach – reference materials include the raw and refined lists, plus the ‘discovered classes’
71 Rule Based Categorization State of the IndustryOnly a handful of rule-based categorizers are on the market todayMost of the existing technologies are dynamic clustering toolsHowever, the market will probably grow in this area as the demand grows
72 Categorization Examples Let’s look at some working examples by going to the Teragram TK240 profilesTopicsCountriesRegionsSectorThemeDisease ProfilesOther categorization profiles we’re also working on…Business processes (characteristics of business processes)Sentiment ratings (positive media statements, negative media statements, etc.)Document types (by characteristics found in the documents)Security classification (by characteristics found in the documents)
73 Topic Hierarchy From Relationships across data classes Build the rules at the lowest level ofcategorization
74 Domain concepts or controlled vocabulary SubtopicsDomain concepts or controlled vocabulary
78 Automatically Generated XML Metadata for Business Function attribute Office memorandum on requesting CD’s clearance of the Board Package for NEPAL: Economic Reforms Technical Assistance (ERTA)
79 Clustering vs. Categorization Clustering Categorization
80 ClusteringWhat is it?The use of statistical and data mining techniques to partition data into sets. Generally the partitioning is based on statistical co-occurrence of words, and their proximity to or distance from each otherHow does it work?Those words that have frequent occurrences close to one another are assigned to the same clusterClusters can be defined at the set or the concept level – usually the latterCan work with a raw training set of text to discover and associate concepts or to suggest ‘buckets’ of conceptsSome few tools can work with refined list of concepts to be clustered against a text corpusPlease note the difference between clustering words in content and clustering domain concepts – major distinction
81 Clustering How do we build it? Define the list of concepts Create the training setLoad the concepts into the clustering engineGenerate the concept clustersState of IndustryMost of the commercial tools that call themselves ‘categorizers’ are actually clustering enginesGenerally, doesn’t work at a high domain level for large sets of textThey can provide insights into concepts in a domain when used on a small set of documentsAll the engines are resource intense, though, and the outputs are transitory – clusters live only in the cluster indexIf you change the text set, the cluster changes
82 Clustering ConceptsThis is from the clustering output for Wildlife Resources.‘Clusters’ of concepts between line breaks are terms from the Wildlife Resources controlled vocabulary found co-occurring in the same training document. This highlights often subtle relationships.
83 Clustering Words in Content Clusters of words based on occurrences in the content
84 Summarization What is it? Rule-driven pattern matching and sentence extraction programsImportant to distinguish summarization technologies from some information extraction technologies - many on the market extract ‘fragments’ of sentences – what Google does when it presents a search result to youWill generate document surrogates, poiint of view summaries, HTML metatag Description, and ‘gist’ or ‘synopsis’ for search indexingResults are sufficient for ‘gisting’ for html metatags, as surrogates for full text document indexing, or as summaries to display in search results to give the user a sense of the contentHow does it work?Uses rules and conditions for selecting sentencesEnables us to define how many sentences to selectAllows us to tell us the concepts to use to select sentencesAllows us to determine where in the sentence the concepts might occurAllows us to exclude sentences from being selectedWe can write multiple sets of rules for different kinds of content
85 Summarization How do we build it? Analyze the content to be summarized to understand the type of speech and writing used – IRIS is different from Publications is different from News storiesIdentify the key concepts that should trigger a sentence extractionIdentify where in the sentence these concepts are likely to occurIdentify the concepts that should be avoidedConvert concepts and conditions to a rule formatLoad the rule file onto the summarization serverTest the rules against test set of content and refine until ‘done’Launch the summarization engine and call the rule fileState of IndustryMost tools are either readers or extractors. Reader method uses clustering & weighting to promote sentence fragments. Extractor method uses internal format representation, word & sentence weightingWhat has been missing from the Extractors in most commercial products is the capability to specify the concepts and the rules. Teragram is the only product we found to support this.
86 Where would appear in the sentence It is likely to be included Summarization RulesCodeWhere would appear in the sentenceIt is likely to be includedSyntax5anywhere in the sentenceIt is likely not to be includedcopyright/2004,59Definitely not includedfor/example,97Definitely to be includedgot/the/top/grade,710pull/off/that/coup,102anywhere in the sentence, followed by the secondevidence,2:collected1beginning of the sentencewe/report,16reporting/on,68copyright/reserved,83beginning of the sentence; only if the preceding sentence qualifieshowever,34the/former,4
88 Step 5. Generate Values for the Ontolog Ontology
89 Sample Dimensions of Ontolog Ontology Names of organizations and companies (Rule based concept extraction)Names of people (Grammar based concept extraction)Countries (Rule based categorization)Ontology facets or subdomains (Grammar based concept extraction + rule based categorization) – Attachment #1Domain Vocabulary/Concept Lists (Grammar based concept extraction) – Attachment #2
90 Step 6. Review and Validation of Ontology Values
91 Expert Review of Facets Are all of the core facets of ontologies included in the list? If not, what is missing?We have identified some facets as related but not essential aspects of ontologies. Have we characterized these correctly? If not, what should be changed?What is included in the list that should not be? This includes both core and related facets.It is generally a good idea to try to limit facets to no more than 30 (what a human mind can retain in short term memory)
92 Expert Review of Concept Lists If you were talking about ontology with an expert, are all of the concepts you would use included in the domain concept list? If not, what is missing?Are there a few concepts missing, or is there a larger subdomain or knowledge area that is missing?What is in the list that is core to ontologies? What is only related to ontologies?If you were looking for information about ontologies – from an expert point of view – would you use any of these concepts to search? Which ones are missing? What shouldn’t be in the list?If you were looking for information about ontologies from a novice’s point of view – what is missing from the list of concepts? What shouldn’t be included?
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