Lecture 24: NER & Entity Linking

Size: px

Start display at page:

Download "Lecture 24: NER & Entity Linking"

Egbert Young
5 years ago
Views:

1 Lecture 24: NER & Entity Linking Kai-Wei Chang University of Virginia kw@kwchang.net Couse webpage: 1

2 Organizing knowledge It s a version of Chicago the standard classic Macintosh menu font, with that distinctive thick diagonal in the N. Chicago was used by default for Mac menus through MacOS 7.6, and OS 8 was released mid Chicago VIII was one of the early 70s-era Chicago albums to catch my ear, along with Chicago II. Slides are adapted from Dan Roth 2

3 Cross-document co-reference resolution It s a version of Chicago the standard classic Macintosh menu font, with that distinctive thick diagonal in the N. Chicago was used by default for Mac menus through MacOS 7.6, and OS 8 was released mid Chicago VIII was one of the early 70s-era Chicago albums to catch my ear, along with Chicago II. 3

4 Reference resolution: (disambiguation to Wikipedia) It s a version of Chicago the standard classic Macintosh menu font, with that distinctive thick diagonal in the N. Chicago was used by default for Mac menus through MacOS 7.6, and OS 8 was released mid Chicago VIII was one of the early 70s-era Chicago albums to catch my ear, along with Chicago II. 4

5 The Reference Collection has Structure It s a version of Chicago the standard classic Macintosh menu font, with that distinctive thick diagonal in the N. Chicago was used by default for Mac menus through MacOS 7.6, and OS 8 was released mid Chicago VIII was one of the early 70s-era Chicago albums to catch my ear, along with Chicago II. Is_a Is_a Used_In Released Succeeded 5

6 Analysis of Information Networks It s a version of Chicago the standard classic Macintosh menu font, with that distinctive thick diagonal in the N. Chicago was used by default for Mac menus through MacOS 7.6, and OS 8 was released mid Chicago VIII was one of the early 70s-era Chicago albums to catch my ear, along with Chicago II. 6

7 Wikipedia as a knowledge resource. Is_a Is_a Used_In Released Succeeded 7

But the Times report has the potential to fundamentally reshape the contest in the Nutmeg State.

8 Wikification: The Reference Problem Blumenthal (D) is a candidate for the U.S. Senate seat now held by Christopher Dodd (D), and he has held a commanding lead in the race since he entered it. But the Times report has the potential to fundamentally reshape the contest in the Nutmeg State. Cycles of Knowledge: Grounding for/using Knowledge Blumenthal (D) is a candidate for the U.S. Senate seat now held by Christopher Dodd (D), and he has held a commanding lead in the race since he entered it. But the Times report has the potential to fundamentally reshape the contest in the Nutmeg State. 8

9 Challenging v Dealing with Ambiguity of Natural Language v Mentions of entities and concepts could have multiple meanings v Dealing with Variability of Natural Language v A given concept could be expressed in many ways v Wikification addresses these two issues in a specific way: v The Reference Problem v What is meant by this concept? (WSD + Grounding) v More than just co-reference (within and across documents) 9

10 General Challenges Blumenthal (D) is a candidate for the U.S. Senate seat now held by Christopher Dodd (D), and he has held a commanding lead in the race since he entered it. But the Times report has the potential to fundamentally reshape the contest in the Nutmeg State. Ambiguity Variability Times The New York Times The Times CT The Nutmeg State Connecticut Concepts outside of Wikipedia (NIL) Blumenthal? Scale Millions of labels 10

11 Wikification: Subtasks v Wikification and Entity Linking requires addressing several sub-tasks: v Identifying Target Mentions v Mentions in the input text that should be Wikified v Identifying Candidate Titles v Candidate Wikipedia titles that could correspond to each mention v Candidate Title Ranking v Rank the candidate titles for a given mention v NIL Detection and Clustering v Identify mentions that do not correspond to a Wikipedia title v Entity Linking: cluster NIL mentions that represent the same entity. 11

12 High-level Algorithmic Approach. v Input: A text document d; Output: a set of pairs (m i,t i ) v m i are mentions in d; t j (m i ) are corresponding Wikipedia titles, or NIL. v v v (1) Identify mentions m i in d (2) Local Inference v For each m i in d: v Identify a set of relevant titles T(m i ) v Rank titles t i T(m i ) [E.g., consider local statistics of edges [(m i,t i ), (m i,*), and (*, t i )] occurrences in the Wikipedia graph] (3) Global Inference v For each document d: v Consider all m i d; and all t i T(m i ) v Re-rank titles t i T(m i ) [E.g., if m, m are related by virtue of being in d, their corresponding titles t, t may also be related] 12

13 Local approach A text Document Identified mentions Wikipedia Articles Γ is a solution to the problem A set of pairs (m,t) m: a mention in the document t: the matched Wikipedia Title Local score of matching the mention to the title (decomposed by m i ) 13

14 Global Approach: Using Additional Structure Text Document(s) News, Blogs, Wikipedia Articles 14 Adding a global term to evaluate how good the structure of the solution is. Use the local solutions Γ (each mention considered independently. Evaluate the structure based on pairwise coherence scores Ψ(t i,t j ) Choose those that satisfy document coherence conditions.

Jianyong Wang Department of Computer Science and Technology Tsinghua University

Jianyong Wang Department of Computer Science and Technology Tsinghua University jianyong@tsinghua.edu.cn Joint work with Wei Shen (Tsinghua), Ping Luo (HP), and Min Wang (HP) Outline Introduction to entity