Ari Rappoport


I am an Associate (Full) Professor at the Hebrew University of Jerusalem, Israel. My main contribution is in the area of Neuroscience, where I developed a comprehensive theory of the brain. My Computer Science area of interest is language (Computational Linguistics, Natural Language Processing (NLP)), from cognitive science and machine learning perspectives.

Neuroscience (2010-present): Research and publications // Language (2002-present): Research, Publications // Geometry (1987-2001): Research, Publications // Contact // Students // Teaching // Business // Picture (Sep 16, 2015)


Brain Research

Understanding brain function is one of the most important problems in human history. I have recently (December 2017) completed a theory describing how the brain works. It is a biological theory, phrased in terms of neurons and proteins. It is comprehensive, accounting for all of the major phenomena, including motor control, functional states, language, and thought. It is concrete, not abstract, showing how high level cognition arises from low level biological processes. It relies on an extensive body of experimental evidence in all known modalities.

Rappoport, Ari. Short Version of `The Brain, Explained': A Response Process Theory of Brain Function. Short version (20 pages) (citation information).
Rappoport, Ari. The Brain, Explained: A Comprehensive Theory of Brain Function. Full version (130 pages) (citation information).
Rappoport, Ari. Basal Ganglia Paths Support Acute vs. Learned Execution, Not Movement vs. Stopping. 19 pages (citation information).

The gist of the theory is as follows. The brain is managed by a response (R) process, comprised of a specific sequence of stages. Different process stages use different brain networks (cortical layers, hippocampal fields, basal ganglia and cerebellum paths, GABAergic interneurons), and are promoted by different molecular agents (e.g., dopamine, serotonin, ACh, opioids, oxytocin). All of the brain's capacities, including motor control, language, and thought, can be shown to be implemented by this elegant architecture. Moreover, the R process is generally similar to the process managing the immune system.

In addition to being comprehensive, the theory provides a dramatically different account from the standard accepted ones for many major topics. For example, the direct and indirect basal ganglia paths do not support movement vs. stopping. On the contrary, they support acute vs. learned action execution. Dopamine is not the brain's `reward' molecule. It supports rapid acting and goal-setting of all types, including aggression. Serotonin does not induce happiness. It promotes thinking. Language does not differ much from motor control, and virtually all of the basic Generative Linguistics tenets stated during the last decades, including recursion, are completely wrong.

Comments are welcome.


Language Research

My Computer Science research area is Computational Linguistics and Natural Language Processing (NLP). I am interested in a wide range of topics, including linguistic semantics (analysis and annotation) and applications (e.g., mining web social media, technology for helping people learn foreign languages).

Both academics and the general public are fascinated by this research area. Our sarcasm detection algorithm was included in Time Magazine's 50 Best Inventions of 2010, and has generated world-wide media coverage.

My lab's current major direction is semantics, with two main projects. (1) We developed 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. (2) We use pattern-based methods for unsupervised acquisition of lexical and relational semantics. We showed their superiority over leading word embeddings in several different settings.

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).

I publish papers in ACL, CoNLL, EMNLP, NAACL, COLING, and EACL, and also in more applied venues related to social media and the web (WSDM, WWW, ICWSM) (see the detailed publication list below). I am routinely a program committee member in ACL, NAACL, EACL, EMNLP, COLING, CoNLL and the ACL workshops on Cognition in NLP, and an occasional one in WSDM, SEM, AAAI and IJCAI. I am one of the organizers of the Workshops on Unsupervised Learning in NLP.


Publications (Language)

NLP publications include papers in ACL (2018 (2), 2017 (2, including the outstanding paper award, +demo), 2016, 2015, 2013, 2011, 2010 (4), 2009, 2008 (4), 2007 (3), 2006), NAACL (2018, 2016), EMNLP (2018, 2013, 2010 (2), 2009 (3)), CoNLL (2018, 2017, 2015, 2010 (3), 2009 (4, including the best paper award)), COLING (2014, 2012 (2), 2010 (3), 2008 (2)), EACL (2009), ICWSM (2015, 2013, 2010, 2009), WSDM (2012), WWW (2012), S2MT (2015), IWCS (2013), and 4 papers in other ACL and EACL workshops (2009, 2007, 2006, 2005). All of these papers except three 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. Elior Sulem, Omri Abend, Ari Rappoport. BLEU is Not Suitable for the Evaluation of Text Simplification. EMNLP 2018.
  2. Daniel Hershcovich, Omri Abend, Ari Rappoport. Multitask Parsing Across Semantic Representations. ACL 2018.
  3. Elior Sulem, Omri Abend, Ari Rappoport. Simple and Effective Text Simplification using Semantic and Neural Methods. ACL 2018.
  4. Elior Sulem, Omri Abend, Ari Rappoport. Semantic Structural Evaluation for Text Simplification. NAACL 2018.
  5. Daniel Hershcovich, Omri Abend, Ari Rappoport. Universal Dependency Parsing with a General Transition-Based DAG Parser. CoNLL 2018 (UD Shared Task).
  6. Daniel Hershcovich, Omri Abend, Ari Rappoport. A Transition-Based Directed Acyclic Graph Parser for UCCA. ACL 2017 (Outstanding Paper Award).
  7. Omri Abend, Ari Rappoport. The State of the Art in Semantic Representation. ACL 2017.
  8. Omri Abend, Shai Yerushalmi, Ari Rappoport. UCCAApp: Web-application for Syntactic and Semantic Phrase-based Annotation. ACL 2017 Demos.
  9. Ivan Vulić, Roy Schwartz, Ari Rappoport, Roi Reichart, Anna Korhonen. Automatic Selection of Context Configurations for Improved Class-Specific Word Representations. CoNLL 2017.
  10. Effi Levi, Roi Reichart, Ari Rappoport. Edge-Linear First-Order Dependency Parsing with Undirected Minimum Spanning Tree Inference. ACL 2016.
  11. Roy Schwartz, Roi Reichart, Ari Rappoport. Symmetric Patterns and Coordinations: Fast and Enhanced Representations of Verbs and Adjectives. NAACL 2016 (short paper).
  12. Dana Rubinstein, Effi Levi, Roy Schwartz, Ari Rappoport. How Well Do Distributional Models Capture Different Types of Semantic Knowledge? ACL 2015 (short paper).
  13. Roy Schwartz, Roi Reichart, Ari Rappoport. Symmetric Pattern Based Word Embeddings for Improved Word Similarity Prediction. CoNLL 2015.
  14. Elior Sulem, Omri Abend, Ari Rappoport. Conceptual Annotations Preserve Structure Across Translations: A French-English Case Study. ACL 2015 Workshop on Semantics-Driven Statistical Machine Translation (S2MT).
  15. Oren Tsur, Ari Rappoport. Donít Let Me Be #Misunderstood: Linguistically Motivated Algorithm for Predicting the Popularity of Textual Memes. International AAAI Conference on Web and Social Media (ICWSM) 2015.
  16. Roy Schwartz, Roi Reichart, Ari Rappoport. Minimally Supervised Classification to Semantic Categories using Automatically Acquired Symmetric Patterns. COLING 2014.
  17. Roy Schwartz, Oren Tsur, Ari Rappoport, Moshe Koppel. Authorship Attribution of Micro-Messages. EMNLP 2013.
  18. Omri Abend, Ari Rappoport. Universal Conceptual Cognitive Annotation (UCCA). ACL 2013. _
  19. Oren Tsur, Adi Littman, Ari Rappoport. Efficient Clustering of Short Messages into General Domains. International AAAI Conference on Web and Social Media (ICWSM) 2013.
  20. Omri Abend, Ari Rappoport. UCCA: A Semantics-based Grammatical Annotation Scheme. ACL/SIGSEM International Conference on Computational Semantics 2013 (IWCS).
  21. Roi Reichart, Gal Elidan, Ari Rappoport. A Diverse Dirichlet Process Ensemble for Unsupervised Induction of Syntactic Categories. COLING 2012.
  22. Roy Schwartz, Omri Abend, Ari Rappoport. Learnability-based Syntactic Annotation Design. COLING 2012.
  23. 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. _
  24. Oren Tsur, Adi Littman, Ari Rappoport. Scalable Multi Stage Clustering of Tagged Micro-Messages. WWW 2012 (short paper).
  25. Roy Schwartz, Omri Abend, Roi Reichart, Ari Rappoport. Neutralizing Linguistically Problematic Annotations in Unsupervised Dependency Parsing Evaluation. ACL 2011. _
  26. Roi Reichart, Ari Rappoport. Tense Sense Disambiguation: a New Syntactic Polysemy Task. Empirical Methods in Natural Language Processing (EMNLP) 2010.
  27. Roi Reichart, Ari Rappoport. Improved Fully Unsupervised Parsing with Zoomed Learning. Empirical Methods in Natural Language Processing (EMNLP) 2010.
  28. Omri Abend, Roi Reichart, Ari Rappoport. Improved Unsupervised POS Induction through Prototype Discovery. ACL 2010.
    (Source code of the algorithm is available here.)
  29. Dmitry Davidov, Ari Rappoport. Extraction and Approximation of Numerical Attributes from the Web. ACL 2010.
  30. Daphna Shezaf, Ari Rappoport. Bilingual Lexicon Generation Using Non-Aligned Signatures. ACL 2010. _
  31. Omri Abend, Ari Rappoport. Fully Unsupervised Core-Adjunct Argument Classification. ACL 2010.
  32. (Time Magazine's 50 Best Inventions of 2010) 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.
  33. Oren Tsur, Dmitry Davidov, Ari Rappoport. Semi-Supervised Recognition of Sarcastic Sentences in Twitter and Amazon. Computational Natural Language Learning (CoNLL) 2010.
  34. Roi Reichart, Omri Abend, Ari Rappoport. Type Level Clustering Evaluation: New Measures and a POS Induction Case Study. Computational Natural Language Learning (CoNLL) 2010.
  35. Roi Reichart, Raanan Fattal, Ari Rappoport. Improved Unsupervised POS Induction Using Intrinsic Clustering Quality and a Zipfian Constraint. Computational Natural Language Learning (CoNLL) 2010.
  36. Dmitry Davidov, Ari Rappoport. Automated Translation of Semantic Relationships. COLING 2010.
  37. Dmitry Davidov, Oren Tsur, Ari Rappoport. Enhanced Sentiment Learning Using Twitter Hashtags and Smileys. COLING 2010. _
  38. Shulamit Umansky-Pesin, Roi Reichart, Ari Rappoport. A Multi-Domain Web-Based Algorithm for POS Tagging of Unknown Words. COLING 2010.

  39. Dmitry Davidov, Ari Rappoport. Geo-mining: Discovery of Road and Transport Networks Using Directional Patterns. EMNLP 2009.
  40. Dmitry Davidov, Ari Rappoport. Enhancement of Lexical Concepts Using Cross-lingual Web Mining. EMNLP 2009.
  41. Ram Boukobza, Ari Rappoport. Multi-Word Expression Identification Using Sentence Surface Features. EMNLP 2009.
  42. Omri Abend, Roi Reichart, Ari Rappoport. Unsupervised Argument Identification for Semantic Role Labeling. ACL 2009. _
  43. Roi Reichart, Ari Rappoport. The NVI Clustering Evaluation Measure. Computational Natural Language Learning (CoNLL) 2009.
    (Source code of the algorithm is available here.)
  44. (Best Paper Award) Roi Reichart, Ari Rappoport. Sample Selection for Statistical Parsers: Cognitively Driven Algorithms and Evaluation Measures. Computational Natural Language Learning (CoNLL) 2009.
  45. Roi Reichart, Ari Rappoport. Automatic Selection of High Quality Parses Created By a Fully Unsupervised Parser. Computational Natural Language Learning (CoNLL) 2009.
  46. 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.
  47. 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). _
  48. Dmitry Davidov, Ari Rappoport. Translation and Extension of Concepts Across Languages. EACL 2009.
  49. 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.

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

  56. Dmitry Davidov, Ari Rappoport, Moshe Koppel. Fully Unsupervised Discovery of Concept-Specific Relationships by Web Mining. Proceedings, ACL 2007. _
  57. Roi Reichart, Ari Rappoport. An Ensemble Method for Selection of High Quality Parses. ACL 2007.
  58. Roi Reichart, Ari Rappoport. Self-Training for Enhancement and Domain Adaptation of Statistical Parsers Trained on Small Datasets. ACL 2007. _
  59. 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. _

  60. Dmitry Davidov, Ari Rappoport. Efficient Unsupervised Discovery of Word Categories Using Symmetric Patterns and High Frequency Words. COLING-ACL 2006. _
  61. 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.
  62. 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


Contact

arir@cs.huji.ac.il. The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Office A402, Rothberg Building, Edmond J. Safra Campus at Givat Ram. Fax: +972-2-549-4504.


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

I am the founder of Bilanga, an online language learning company. We provide English learning software based on state-of-the-art concepts in neuroscience, cognitive science, applied linguistics and computer science. The software is cloud-based, fully personalized and fully automated. It was designed to both complement class-based teaching and to allow efficient self-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.