Prof. Ari Rappoport


My main area of interest is language (brain representation and processing, Computational Linguistics, Natural Language Processing). In the past, I have worked in Geometric and Solid Modeling, Computer Graphics and Video and Image Processing.

Language Research // Geometry Research // Publications (Language) // Publications (Geometry) // Addresses Etc // Students // Teaching // Business


Language Research

My current research area is Computational Linguistics and Natural Language Processing (NLP). I am interested in a wide range of topics, including language in the brain, utterance semantics, lexical semantics, the semantics-form interface (syntax), and applications (e.g., mining web social media, technology for helping people read in foreign languages).

My lab's major current project is UCCA, Universal Conceptual Cognitive Annotation of natural language texts. UCCA annotation is purely semantic, letting automated algorithms derive syntax (regularities in the mapping between forms and meanings). // An interactive UCCA web annotation application can be accessed here.

Our less recent focus was on using fully unsupervised and semi-supervised methods, in order to make use of the huge corpora available today and to overcome the problems associated with manual syntactic annotation (annotation cost and the arbitrariness of annotation schemes).

The general public is, perhaps not surprisingly, highly interested in computational language applications. Our sarcasm detection algorithm was selected by Time Magazine as one of the 50 Best Inventions of 2010, and has generated a lot of world-wide media coverage.

I publish papers mostly in NLP forums (ACL, CoNLL, EMNLP, COLING, EACL), with some in more applied venues related to social media and the web (WSDM, WWW, ICWSM); see a detailed publication list below. I am routinely a program committee member in ACL, NAACL, EACL, EMNLP, COLING, CoNLL, and LREC, and occasionally in WSDM, SEM, AAAI, IJCAI, and various ACL workshops (including Cognitive Aspects of Computational Language Acquisition and Computational Neurolinguistics).

I am one of the organizers of the Workshops on Unsupervised Learning in NLP. I was the program chair for the 2007 Israel Seminar on Computational Linguistics (ISCOL '07).


Publications (Language)

NLP publications include papers in COLING 2014 (1), ACL 2013 (1), EMNLP 2013 (1), IWCS 2013 (1), ICWSM 2013 (1), WSDM 2012 (1), WWW 2012 (1), COLING 2012 (2), ACL 2011 (1), ACL 2010 (4), CoNLL 2010 (3), COLING 2010 (3), EMNLP 2010 (2), EMNLP 2009 (3), CoNLL 2009 (4, including the best paper award), ACL 2009 (1), EACL 2009 (1), ACL 2008 (4), COLING 2008 (2), ACL 2007 (3), ACL 2006 (1), ICWSM 2010 (1), ICWSM 2009 (1), and 4 papers in ACL and EACL workshops (2009, 2007, 2006, 2005).
All of these papers except one are long papers.
Source code is available for dependency annotation design using learnability, Neutral Edge Direction (NED) dependency parsing evaluation measure, prototype POS induction and clustering evaluation.
  1. Roy Schwartz, Roi Reichart, Ari Rappoport. Minimally Supervised Classification to Semantic Categories using Automatically Acquired Symmetric Patterns. COLING 2014.
  2. Roy Schwartz, Oren Tsur, Ari Rappoport, Moshe Koppel. Authorship Attribution of Micro-Messages. EMNLP 2013.
  3. Omri Abend, Ari Rappoport. Universal Conceptual Cognitive Annotation (UCCA). ACL 2013. _
  4. Oren Tsur, Adi Littman, Ari Rappoport. Efficient Clustering of Short Messages into General Domains. ICWSM 2013.
  5. Omri Abend, Ari Rappoport. UCCA: A Semantics-based Grammatical Annotation Scheme. ACL/SIGSEM International Conference on Computational Semantics 2013 (IWCS).
  6. Roi Reichart, Gal Elidan, Ari Rappoport. A Diverse Dirichlet Process Ensemble for Unsupervised Induction of Syntactic Categories. COLING 2012.
  7. Roy Schwartz, Omri Abend, Ari Rappoport. Learnability-based Syntactic Annotation Design. COLING 2012.
  8. Oren Tsur, Ari Rappoport. What's in a Hashtag? Content based Prediction of the Spread of Ideas in Microblogging Communities. Web Search and Data Mining (WSDM) 2012. _
  9. Oren Tsur, Adi Littman, Ari Rappoport. Scalable Multi Stage Clustering of Tagged Micro-Messages. WWW 2012 (short paper).
  10. Roy Schwartz, Omri Abend, Roi Reichart, Ari Rappoport. Neutralizing Linguistically Problematic Annotations in Unsupervised Dependency Parsing Evaluation. ACL 2011. _
  11. Roi Reichart, Ari Rappoport. Tense Sense Disambiguation: a New Syntactic Polysemy Task. Empirical Methods in Natural Language Processing (EMNLP) 2010.
  12. Roi Reichart, Ari Rappoport. Improved Fully Unsupervised Parsing with Zoomed Learning. Empirical Methods in Natural Language Processing (EMNLP) 2010.
  13. Omri Abend, Roi Reichart, Ari Rappoport. Improved Unsupervised POS Induction through Prototype Discovery. ACL 2010.
    (Source code of the algorithm is available here.)
  14. Dmitry Davidov, Ari Rappoport. Extraction and Approximation of Numerical Attributes from the Web. ACL 2010.
  15. Daphna Shezaf, Ari Rappoport. Bilingual Lexicon Generation Using Non-Aligned Signatures. ACL 2010. _
  16. Omri Abend, Ari Rappoport. Fully Unsupervised Core-Adjunct Argument Classification. ACL 2010.
  17. Oren Tsur, Dmitry Davidov, Ari Rappoport. ICWSM - A Great Catchy Name: Semi-Supervised Recognition of Sarcastic Sentences in Product Reviews. Fourth International AAAI Conference on Weblogs and Social Media (ICWSM 2010).
  18. Oren Tsur, Dmitry Davidov, Ari Rappoport. Semi-Supervised Recognition of Sarcastic Sentences in Twitter and Amazon. Computational Natural Language Learning (CoNLL) 2010.
  19. Roi Reichart, Omri Abend, Ari Rappoport. Type Level Clustering Evaluation: New Measures and a POS Induction Case Study. Computational Natural Language Learning (CoNLL) 2010.
  20. Roi Reichart, Raanan Fattal, Ari Rappoport. Improved Unsupervised POS Induction Using Intrinsic Clustering Quality and a Zipfian Constraint. Computational Natural Language Learning (CoNLL) 2010.
  21. Dmitry Davidov, Ari Rappoport. Automated Translation of Semantic Relationships. COLING 2010.
  22. Dmitry Davidov, Oren Tsur, Ari Rappoport. Enhanced Sentiment Learning Using Twitter Hashtags and Smileys. COLING 2010. _
  23. Shulamit Umansky-Pesin, Roi Reichart, Ari Rappoport. A Multi-Domain Web-Based Algorithm for POS Tagging of Unknown Words. COLING 2010.

  24. Dmitry Davidov, Ari Rappoport. Geo-mining: Discovery of Road and Transport Networks Using Directional Patterns. EMNLP 2009.
  25. Dmitry Davidov, Ari Rappoport. Enhancement of Lexical Concepts Using Cross-lingual Web Mining. EMNLP 2009.
  26. Ram Boukobza, Ari Rappoport. Multi-Word Expression Identification Using Sentence Surface Features. EMNLP 2009.
  27. Omri Abend, Roi Reichart, Ari Rappoport. Unsupervised Argument Identification for Semantic Role Labeling. ACL 2009. _
  28. Roi Reichart, Ari Rappoport. The NVI Clustering Evaluation Measure. Computational Natural Language Learning (CoNLL) 2009.
    (Source code of the algorithm is available here.)
  29. (BEST PAPER AWARD) Roi Reichart, Ari Rappoport. Sample Selection for Statistical Parsers: Cognitively Driven Algorithms and Evaluation Measures. Computational Natural Language Learning (CoNLL) 2009.
  30. Roi Reichart, Ari Rappoport. Automatic Selection of High Quality Parses Created By a Fully Unsupervised Parser. Computational Natural Language Learning (CoNLL) 2009.
  31. Dmitry Davidov, Roi Reichart, Ari Rappoport. Superior and Efficient Fully Unsupervised Pattern-based Concept Acquisition Using an Unsupervised Parser. Computational Natural Language Learning (CoNLL) 2009.
  32. Oren Tsur, Ari Rappoport. RevRank: a Fully Unsupervised Algorithm for Selecting the Most Helpful Book Reviews. Third International AAAI Conference on Weblogs and Social Media (ICWSM 2009). _
  33. Dmitry Davidov, Ari Rappoport. Translation and Extension of Concepts Across Languages. EACL 2009.
  34. Elad Dinur, Dmitry Davidov, Ari Rappoport. Unsupervised Concept Discovery In Hebrew Using Simple Unsupervised Word Prefix Segmentation for Hebrew and Arabic. EACL 2009 Workshop on Computational Approaches to Semitic Languages.

  35. Dmitry Davidov, Ari Rappoport. Unsupervised Discovery of Generic Relationships Using Pattern Clusters and its Evaluation by Automatically Generated SAT Analogy Questions. ACL 2008. _
  36. Dmitry Davidov, Ari Rappoport. Classification of Semantic Relationships between Nominals Using Pattern Clusters. ACL 2008. _
  37. Vivek Srikumar, Roi Reichart, Mark Sammons, Ari Rappoport, Dan Roth. Extraction of Entailed Semantic Relations Through Syntax-based Comma Resolution. ACL 2008.
  38. Roi Reichart, Katrin Tomanek, Udo Hahn, Ari Rappoport. Multi-Task Active Learning for Linguistic Annotations. ACL 2008. _
  39. Omri Abend, Roi Reichart, Ari Rappoport. A Supervised Algorithm for Verb Disambiguation into VerbNet Classes. COLING 2008.
  40. Roi Reichart, Ari Rappoport. Unsupervised Induction of Labeled Parse Trees by Clustering with Syntactic Features. COLING 2008.

  41. Dmitry Davidov, Ari Rappoport, Moshe Koppel. Fully Unsupervised Discovery of Concept-Specific Relationships by Web Mining. Proceedings, ACL 2007. _
  42. Roi Reichart, Ari Rappoport. An Ensemble Method for Selection of High Quality Parses. ACL 2007.
  43. Roi Reichart, Ari Rappoport. Self-Training for Enhancement and Domain Adaptation of Statistical Parsers Trained on Small Datasets. ACL 2007. _
  44. Oren Tsur, Ari Rappoport. Using Classifier Features for Studying the Effect of Native Language on the Choice of Written Second Language Words. Proceedings, ACL 2007 Workshop on Cognitive Aspects of Computational Language Acquisition, June 2007, Prague. _

  45. Dmitry Davidov, Ari Rappoport. Efficient Unsupervised Discovery of Word Categories Using Symmetric Patterns and High Frequency Words. COLING-ACL 2006. _
  46. Ari Rappoport, Tsahi Levent-Levi. Induction of Cross-Language Affix and Letter Sequence Correspondence. Proceedings, EACL 2006 Workshop on Cross-Language Knowledge Induction, April 2006, Trento, Italy.
  47. Ari Rappoport, Vera Sheinman. A Second Language Acquisition Model Using Example Generalization and Concept Categories. Proceedings, ACL 2005 Workshop on Psycho-computational Models of Human Language Acquisition, June 2005, Ann Arbor.

Geometry Research

Research: The theme that ties most of my research in geometric modeling and computer graphics is the notion of "families of geometric objects" (see UPR and feature-based data exchange project page, and GGC, shape animation, parametric fonts, 2-D+surface+volume preservation constraints, real-time Booleans, below). A second theme is the study of fundamental geometric structures (see medial axis, Voronoi graph, ECDT, compatible decompositions). In addition, I enjoy doing research on various cool graphics subjects (see real-time reflections, textures from image sequences, 3-D effects on still images, image-based rendering).

Community: In 1992 I started the Geometric Modeling and Computer Graphics Lab at HUJI, after a postdoc at the IBM TJ Watson Research Center in New York. I was an associate editor of ACM Transactions on Graphics, and a paper committee member for Solid Modeling '95, Eurographics '96, CSG '96, Theory and Practice of Geometric Modeling (Blaubeuren II) 1996, Solid Modeling '97, TeamCAD '97, Eurographics '97, Computer Graphics International '98, CSG '98, Eurographics '98, the 1999 ACM/Siggraph Symposium on Interactive 3D Graphics, Solid Modeling '99, Eurographics '99, Computer Graphics International '99, International Conference on Visual Computing ICVC '99, Pacific Graphics '99, Geometric Modeling and Processing 2000, Solid Modeling '04, Solid and Physical Modeling '05, Shape Modeling International '05, Solid and Physical Modeling '06, Shape Modeling International '06, Solid and Physical Modeling '07, Shape Modeling International '07, International Conference on Computer Graphics Theory and Applications (GRAPP) '07, Solid and Physical Modeling '08, Shape Modeling International '08, Computer Graphics International (CGI) '08, Product Life-Cycle (PLM) '08, International Conference on Computer Graphics Theory and Applications (GRAPP) '08, Solid and Physical Modeling 2009, 2010, 2011, and Shape Modeling International 2009, 2010, 2011.


Publications (Geometry)

Following is a partial list of publications, arranged according to topic. Clicking on a paper's title leads to its abstract. Some papers contain links to pdf versions of the full paper. To obtain other full papers please email me personally.

The Universal Product Representation // Voronoi Graph (Medial Axis) // Interactive Rendering // Generative and Declarative Modeling // Polygons and Polyhedra // Digital Typography // Curves, Surfaces and Volumes // Morphing and Deformations // Images and Video // User Interface //

The Universal Product Representation

The Voronoi Graph (Medial Axis)

Interactive Rendering

Generative and Declarative Modeling

Representations and Algorithms for Polygons and Polyhedra

Digital Typography

Curves, Surfaces and Volumes

Morphing and Deformations

Modeling and Rendering from Images and Image Sequences

User Interface


Addresses Etc

The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. arir, AT symbol, cs huji ac il Office A535, Rothberg Building, Edmond J. Safra Campus at Givat Ram. Fax: +972-2-549-4605.


Students

Graduate (PhD, MSc) and Amirim

Alumni


Teaching

Human Language from a Computational Perspective (an "Avney Pina" course) // Natural Language Processing (NLP) / Computational Linguistics Seminar // Hightech Entrepreneurship // Guided Projects and Lab Projects in Computational Linguistics // Guided Projects and Lab Projects in Internet Technologies and Software Development


Business

My current focus is on novel methods for online language learning. I have been involved in various roles with high-tech companies and venture capital funds since 1994, in areas including cognitive enhancement and training, algorithmic trading, computer-aided design, computer graphics, and image and video processing. // Proficiency, an enterprise software company I started in 1998, sells collaborative engineering software to customers such as Ford, Boeing, and Honda. After some ups and downs, the company has been acquired by ITI TranscenData Inc.