CLEOPATRA HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk & Elena Demidova L3S Research Center, Leibniz Universität Hannover HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 1 Challenge: Knowledge Graph Completion ● Knowledge Graphs (KGs) such as DBpedia and Wikidata are incomplete by nature ⇨ Need for KG completion HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 2 Challenge: Knowledge Graph Completion ● Knowledge Graphs (KGs) such as DBpedia and Wikidata are incomplete by nature ⇨ Need for KG completion ● Existing approaches ● Link prediction HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 3 Challenge: Knowledge Graph Completion ● Knowledge Graphs (KGs) such as DBpedia and Wikidata are incomplete by nature ⇨ Need for KG completion ● Existing approaches ● Link prediction ● Utilize knowledge from external sources ……… ……… ……… ….. HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 4 Challenge: Knowledge Graph Completion ● Knowledge Graphs (KGs) such as DBpedia and Wikidata are incomplete by nature ⇨ Need for KG completion ● Existing approaches ● Link prediction ● Utilize knowledge from external sources How to enrich KGs by adding new nodes, without relying on external knowledge? HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 5 Solution: KG Completion in Event Series ● KG completion for event series, such as ● Wimbledon Tennis Championships ● US presidential elections ● International Semantic Web Conference ● Event series are often covered incompletely ● focus on recent and current events ● Event series editions often follow similar patterns ⇨ use structural similarity to infer new events HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 6 Wikidata Example: Wimbledon Championships HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 7 Wikidata Example: Wimbledon Championships Wimbledon Championships 2019 Men's Men's Women's Women's Mixed Singles Doubles Singles Doubles Doubles Final Final Final Final Final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 8 History of the Wimbledon Championships 1877 1885 2018 2019 HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 9 Incomplete Knowledge Graph: Missing Edge 1877 1885 2018 2019 HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 10 Incomplete Knowledge Graph: Missing Node 1877 1885 2018 2019 HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 11 Approach 1. Definition of event series graphs ● Event series and sub-event relations 2. Sub-event relation prediction ● Find new sub-event relations ● Binary classification problem 3. Event inference ● Infer new events ● Add event description ○ Label, time and location HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 12 Wimbledon Example: Event Series Graph 2008 Wimbledon 2009 Wimbledon 2010 Wimbledon Championships Championships Championships HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 13 Wimbledon Example: Event Series Graph Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 14 Wimbledon Example: Event Series Graph Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships sub-event relation 2008 Wimbledon “2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Men's Singles Men's Singles” Men's Singles Event Series: Wimbledon Championships – Men's Singles HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 15 Wimbledon Example: Event Series Graph Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships sub-event relation 2008 Wimbledon “2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Men's Singles Men's Singles” Men's Singles 2009 Wimbledon Championships – Men's Singles final Event Series: Wimbledon Championships Event Series: Wimbledon Championships – Men's Singles – Men's Singles final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 16 Wimbledon Example: Event Series Graph Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships sub-event relation 2008 Wimbledon “2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Men's Singles Men's Singles” Men's Singles 2008 Wimbledon Championships – 2009 Wimbledon Men's Singles final Championships – Men's Singles final Event Series: Wimbledon Championships Event Series: Wimbledon Championships – Men's Singles – Men's Singles final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 17 Wimbledon Example: Sub-Event Relation Prediction Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships sub-event relation 2008 Wimbledon “2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Men's Singles Men's Singles” Men's Singles Predicted sub-event relation 2008 Wimbledon 2009 Wimbledon Championships – Championships – Men's Singles final Men's Singles final Event Series: Wimbledon Championships Event Series: Wimbledon Championships – Men's Singles – Men's Singles final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 18 Wimbledon Example: Event Inference Event Series: Wimbledon Championships follow-up 2008 Wimbledon relation 2009 Wimbledon 2010 Wimbledon Championships Championships Championships sub-event relation 2008 Wimbledon “2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Men's Singles Men's Singles” Men's Singles Predicted sub-event relation 2008 Wimbledon 2009 Wimbledon 2010 Wimbledon Championships – Championships – Championships – Inferred Men's Singles final Men's Singles final Men's Singles final event Event Series: Wimbledon Championships Event Series: Wimbledon Championships – Men's Singles – Men's Singles final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 19 Sub-Event Relation Prediction I ep: 2008 Wimbledon ● Binary classification problem Championships – Men's Singles ○ Given an event pair (es, ep), we aim to predict whether es is a sub-event of ep es: 2008 Wimbledon ● Features Championships – ○ STransE embedding score Men's Singles final ○ Textual features based on labels and template labels - Template of "2008 Wimbledon Championships": "Wimbledon Championships" ○ Spatio-temporal features - Time overlap, time containment, time equality - Location overlap HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 20 Sub-Event Relation Prediction II ep: 2008 Wimbledon ● Binary classification problem Championships – Men's Singles ○ Given an event pair (es, ep), we aim to predict whether es is a sub-event of ep es: 2008 Wimbledon ● For each event in a series that does not have a Championships – sub-event: Find potential sub-events Men's Singles final ● Repeat that search until all leaf nodes were tested ● Training based on a balanced set of positive and difficult negative examples HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 21 Event Inference 2010 Wimbledon ● If an event is repeated in most editions of an Championships – event series, but is missing in a particular Men's Singles edition, we can infer that missing event 2010 Wimbledon ● Label, time and location generation for each Championships – Men's Singles final new event HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 22 Event Inference — Example e.series: Wimbledon Championships – Men's Singles 2008 Wimbledon 2009 Wimbledon e: 2010 Wimbledon Championships – Men's Championships – Men's Championships – Men's Singles Singles Singles 2008 Wimbledon 2009 Wimbledon Championships – Men's Championships – Men's Singles final Singles final m ∈ M: Wimbledon Championships – Men's Singles final HapPenIng: Happen, Predict, Infer — Event Series Completion in a Knowledge Graph Simon Gottschalk, Elena Demidova 23 Event Inference — Example e.series: Wimbledon Championships – Men's Singles 2008 Wimbledon 2009 Wimbledon e: 2010 Wimbledon Championships – Men's Championships – Men's Championships – Men's Singles