知识图谱梳理专题培训课件.ppt
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- 知识 图谱 梳理 专题 培训 课件
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1、知识图谱架构知识图谱一般架构:来源自百度百科复旦大学知识图谱架构:早期知识图谱架构知识图谱一般架构:来源自百度百科架构讨论早期知识图谱架构知识抽取实体概念抽取实体概念映射关系抽取质量评估KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014A sampler of research problemsGrowth: knowledge graphs are incomplete!Link prediction: add relationsOntology
2、matching: connect graphsKnowledge extraction: extract new entities and relations from web/textValidation: knowledge graphs are not always correct!Entity resolution: merge duplicate entities, split wrongly merged onesError detection: remove false assertionsInterface: how to make it easier to access k
3、nowledge?Semantic parsing: interpret the meaning of queriesQuestion answering: compute answers using the knowledge graphIntelligence: can AI emerge from knowledge graphs?Automatic reasoning and planningGeneralization and abstraction9关系抽取 定义: 常见手段: 语义模式匹配频繁模式抽取,基于密度聚类,基于语义相似性 层次主题模型弱监督KDD 2014 Tutori
4、al on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Methods and techniquesSupervised modelsSemi-supervised modelsDistant supervision2. Entity resolutionSingle entity methodsRelational methods3. Link predictionRule-based methodsProbabilistic modelsFactorization methodsE
5、mbedding models80Not in this tutorial: Entity classification Group/expert detection Ontology alignment Object ranking1. Relation extraction:KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014 Extracting semantic relations between sets of grounded entiti
6、esNumerous variants:Undefined vs pre-determined set of relationsBinary vs n-ary relations, facet discoveryExtracting temporal informationSupervision: fully, un, semi, distant-supervisionCues used: only lexical vs full linguistic features82Relation ExtractionKobeBryantLA LakersplayForthe franchise pl
7、ayer ofonce again savedman of the match forthe Lakers”his team”Los Angeles”“Kobe Bryant,“Kobe“Kobe Bryant?KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Supervised relation extractionSentence-level labels of relation mentionsApple CEO Steve Jobs sai
8、d. = (SteveJobs, CEO, Apple)Steve Jobs said that Apple will. = NILTraditional relation extraction datasetsACE 2004MUC-7Biomedical datasets (e.g BioNLP clallenges)Learn classifiers from +/- examplesTypical features: context words + POS, dependency path betweenentities, named entity tags, token/parse-
9、path/entity distance83KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Semi-supervised relation extractionGeneric algorithm(遗传算法遗传算法)1.2.3.4.5.Start with seed triples / golden seed patternsExtract patterns that match seed triples/patternsTake the top-
10、k extracted patterns/triplesAdd to seed patterns/triplesGo to 2Many published approaches in this category:Dual Iterative Pattern Relation Extractor Brin, 98Snowball Agichtein & Gravano, 00TextRunner Banko et al., 07 almost unsupervisedDiffer in pattern definition and selection86founderOfKDD 2014 Tut
11、orial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Distantly-supervised relation extraction88Existing knowledge base + unlabeled text generate examplesLocate pairs of related entities in textHypothesizes that the relation is expressedGoogle CEO Larry Page announced
12、 that.Steve Jobs has been Apple for a while.Pixar lost its co-founder Steve Jobs.I went to Paris, France for the summer.GoogleCEOcapitalOfLarryPageFranceAppleCEOPixarSteveJobsDistant supervision: modeling hypothesesTypical architecture:1. Collect many pairs of entities co-occurring in sentences from
13、 text corpus2. If 2 entities participate in a relation, several hypotheses:1.All sentences mentioning them express it Mintz et al., 09“Barack Obama is the 44th and current President of the US.” (BO, employedBy, USA)89KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York,
14、August 24, 2014KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Sentence-level featuresLexical: words in between and around mentions and their parts-of-speech tags (conjunctive form)Syntactic: dependency parse path between mentions along withside node
15、sNamed Entity Tags: for the mentionsConjunctions of the above featuresDistant supervision is used on to lots of data sparsity of conjunctiveforms not an issue92Distant supervision: modeling hypothesesTypical architecture:1. Collect many pairs of entities co-occurring in sentences from text corpus2.
16、If 2 entities participate in a relation, several hypotheses:1.2.All sentences mentioning them express it Mintz et al., 09At least one sentence mentioning them express it Riedel et al., 10“Barack Obama is the 44th and current President of the US.” (BO, employedBy, USA)“Obama flew back to the US on We
17、dnesday.” (BO, employedBy, USA)95KDD 2014 Tutorial on Constructing and Mining Web-scale Knowledge Graphs, New York, August 24, 2014Distant supervision: modeling hypothesesTypical architecture:1. Collect many pairs of entities co-occurring in sentences from text corpus2. If 2 entities participate in
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