Ari Rappoport's homepage

Ari Rappoport

I am an Associate (Full) Professor at the Hebrew University of Jerusalem, Israel. My main contribution is in the areas of Neuroscience, Neurology, and Psychiatry, where I developed comprehensive theories of the brain and brain disorders and diseases. 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 // Picture (Sep 16, 2015)

Brain Research

To develop the theories below, I thoroughly examined the scientific literature, covering a large part of the relevant papers published in the last decades (hundreds of thousands of papers). I discovered that published papers already contain evidence for almost all of the lower-level details needed for developing complete theories. In each disorder/disease, what was needed is a high-level coherent story to connect these pieces of evidence (i.e., a theory). This is what my papers present. In many cases, the drugs to treat these disorders already exist and are routinely used for other indications.

Disorders and Diseases

Rappoport, Ari. A Lipid Rafts Theory of Alzheimer's Disease (October 2023. In press, Annual Review of Biochemistry, Volume 94). This paper presents the first complete theory of Alzheimer's Disease (AD), explaining its etiology, symptoms, pathology, and risk factors. The causal mechanism in AD is impaired formation of plasma membrane lipid rafts, which are essential for the conversion of short-term to long-term memory and for convergence of brain plasticity processes. The core cause of AD is reduced neural uptake and intracellular trafficking of cholesterol.
Rappoport, Ari. A Polyunsaturated Fatty Acid (PUFA) Theory of Schizophrenia.
Rappoport, Ari. A Dynorphin Theory of Depression and Bipolar Disorder.
Rappoport, Ari. A Sympathetic Nervous System Theory of Migraine.
Rappoport, Ari. A CRH Theory of Autism Spectrum Disorder.
Rappoport, Ari. A KATP Channel Theory of Attention-Deficit Hyperactivity Disorder.
Rappoport, Ari. A CRH-HCN Theory of Obsessive-Compulsive Disorder (OCD).
Rappoport, Ari. Uploaded to Arxiv, waiting approval: a complete theory of anorexia and bulimia.
Rappoport, Ari. Uploaded to Arxiv, waiting approval: a complete theory of Parkinson's Disease.
Rappoport, Ari. Uploaded to Arxiv, waiting approval: a complete theory of multiple sclerosis demyelinization.
Rappoport, Ari. Completed, to be uploaded to Arxiv: a complete theory of amyotrophic lateral sclerosis and frontotemporal dementia.
Rappoport, Ari. Insulin in Amyotrophic Lateral Sclerosis: Impairment, Tests and Treatment (January 2023). The paper shows that insulin function is impaired in ALS patients (even patients with normal glucose levels who are not diagnosed with diabetes), explains why this happens, discusses the possible usage of insulin-affecting drugs in treating ALS, and proposes biomarker tests. The proposed tests are immediately available in any medical facility, and physicians are allowed to use them without any special approval.

Updated 9.9.24.

Neuroscience

Rappoport, Ari. The Brain, Explained: A Comprehensive Theory of Brain Function (Dec 2017). Full version (130 pages) (citation information). This version contains a 3-page extended abstract that serves as a short introduction to the theory.
Rappoport, Ari. Short Version of `The Brain, Explained': A Response Process Theory of Brain Function (2018). Short version (20 pages) (citation information). This paper summarizes the long version, presenting the main ideas of the theory.
November 2023: I have significantly improved both the presentation of the brain theory and many of its mechanistic details. Major updates will eventually be published.
Rappoport, Ari. Basal Ganglia Paths Support Acute vs. Learned Execution, Not Movement vs. Stopping (June 2018. 2nd version May 2019). 22 pages (citation information). This paper focuses on the basal ganglia, showing how the brain theory allows a novel understanding of BG paths and of the main symptoms of Parkinson's disease.
Specifically, the paper shows that the role of the indirect path is to support learned movements, a view that stands in sharp contrast to the accepted account in which it suppresses movement.
Rappoport, Ari. A Comprehensive Biological Theory of Sleep (April 2019. An improved 2nd version is available upon request, Feb 2020). 32 pages (citation information). This paper presents a theory that covers the roles and mechanisms of sleep, rapid-eye movement (REM) sleep, NREM sleep, dreaming, and anesthesia.

Updated 1.11.23.

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)

Elior Sulem, Omri Abend, Ari Rappoport. Semantic Structural Decomposition for Neural Machine Translation. Lexical and Computational Semantics (*SEM) 2020.
Daniel Hershcovich, Omri Abend, Ari Rappoport. Content Differences in Syntactic and Semantic Representation. NAACL 2019.
Adi Shalev, Jena D. Hwang, Nathan Schneider, Vivek Srikumar, Omri Abend. Ari Rappoport. Preparing SNACS for Subjects and Objects. Designing Meaning Representations Workshop (ACL 2019).
Daniel Hershcovich, Zohar Aizenbud, Leshem Choshen, Elior Sulem, Ari Rappoport, Omri Abend. SemEval-2019 Task 1: Cross-lingual Semantic Parsing with UCCA. SemEval 2019 (International Workshop on Semantic Evaluation, NAACL-HTL 2019).
Elior Sulem, Omri Abend, Ari Rappoport. BLEU is Not Suitable for the Evaluation of Text Simplification. EMNLP 2018.
Daniel Hershcovich, Omri Abend, Ari Rappoport. Multitask Parsing Across Semantic Representations. ACL 2018.
Elior Sulem, Omri Abend, Ari Rappoport. Simple and Effective Text Simplification using Semantic and Neural Methods. ACL 2018.
Elior Sulem, Omri Abend, Ari Rappoport. Semantic Structural Evaluation for Text Simplification. NAACL 2018.
Daniel Hershcovich, Omri Abend, Ari Rappoport. Universal Dependency Parsing with a General Transition-Based DAG Parser. CoNLL 2018 (UD Shared Task).
Daniel Hershcovich, Omri Abend, Ari Rappoport. A Transition-Based Directed Acyclic Graph Parser for UCCA. ACL 2017 (Outstanding Paper Award).
Omri Abend, Ari Rappoport. The State of the Art in Semantic Representation. ACL 2017.
Omri Abend, Shai Yerushalmi, Ari Rappoport. UCCAApp: Web-application for Syntactic and Semantic Phrase-based Annotation. ACL 2017 Demos.
Ivan Vulić, Roy Schwartz, Ari Rappoport, Roi Reichart, Anna Korhonen. Automatic Selection of Context Configurations for Improved Class-Specific Word Representations. CoNLL 2017.
Effi Levi, Roi Reichart, Ari Rappoport. Edge-Linear First-Order Dependency Parsing with Undirected Minimum Spanning Tree Inference. ACL 2016.
Roy Schwartz, Roi Reichart, Ari Rappoport. Symmetric Patterns and Coordinations: Fast and Enhanced Representations of Verbs and Adjectives. NAACL 2016 (short paper).
Dana Rubinstein, Effi Levi, Roy Schwartz, Ari Rappoport. How Well Do Distributional Models Capture Different Types of Semantic Knowledge? ACL 2015 (short paper).
Roy Schwartz, Roi Reichart, Ari Rappoport. Symmetric Pattern Based Word Embeddings for Improved Word Similarity Prediction. CoNLL 2015.
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).
Oren Tsur, Ari Rappoport. Don’t Let Me Be #Misunderstood: Linguistically Motivated Algorithm for Predicting the Popularity of Textual Memes. International AAAI Conference on Web and Social Media (ICWSM) 2015.
Roy Schwartz, Roi Reichart, Ari Rappoport. Minimally Supervised Classification to Semantic Categories using Automatically Acquired Symmetric Patterns. COLING 2014.
Roy Schwartz, Oren Tsur, Ari Rappoport, Moshe Koppel. Authorship Attribution of Micro-Messages. EMNLP 2013.
Omri Abend, Ari Rappoport. Universal Conceptual Cognitive Annotation (UCCA). ACL 2013. _
Oren Tsur, Adi Littman, Ari Rappoport. Efficient Clustering of Short Messages into General Domains. International AAAI Conference on Web and Social Media (ICWSM) 2013.
Omri Abend, Ari Rappoport. UCCA: A Semantics-based Grammatical Annotation Scheme. ACL/SIGSEM International Conference on Computational Semantics 2013 (IWCS).
Roi Reichart, Gal Elidan, Ari Rappoport. A Diverse Dirichlet Process Ensemble for Unsupervised Induction of Syntactic Categories. COLING 2012.
Roy Schwartz, Omri Abend, Ari Rappoport. Learnability-based Syntactic Annotation Design. COLING 2012.
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. _
Oren Tsur, Adi Littman, Ari Rappoport. Scalable Multi Stage Clustering of Tagged Micro-Messages. WWW 2012 (short paper).
Roy Schwartz, Omri Abend, Roi Reichart, Ari Rappoport. Neutralizing Linguistically Problematic Annotations in Unsupervised Dependency Parsing Evaluation. ACL 2011. _
Roi Reichart, Ari Rappoport. Tense Sense Disambiguation: a New Syntactic Polysemy Task. Empirical Methods in Natural Language Processing (EMNLP) 2010.
Roi Reichart, Ari Rappoport. Improved Fully Unsupervised Parsing with Zoomed Learning. Empirical Methods in Natural Language Processing (EMNLP) 2010.
Omri Abend, Roi Reichart, Ari Rappoport. Improved Unsupervised POS Induction through Prototype Discovery. ACL 2010.
(Source code of the algorithm is available here.)
Dmitry Davidov, Ari Rappoport. Extraction and Approximation of Numerical Attributes from the Web. ACL 2010.
Daphna Shezaf, Ari Rappoport. Bilingual Lexicon Generation Using Non-Aligned Signatures. ACL 2010. _
Omri Abend, Ari Rappoport. Fully Unsupervised Core-Adjunct Argument Classification. ACL 2010.
(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.
Oren Tsur, Dmitry Davidov, Ari Rappoport. Semi-Supervised Recognition of Sarcastic Sentences in Twitter and Amazon. Computational Natural Language Learning (CoNLL) 2010.
Roi Reichart, Omri Abend, Ari Rappoport. Type Level Clustering Evaluation: New Measures and a POS Induction Case Study. Computational Natural Language Learning (CoNLL) 2010.
Roi Reichart, Raanan Fattal, Ari Rappoport. Improved Unsupervised POS Induction Using Intrinsic Clustering Quality and a Zipfian Constraint. Computational Natural Language Learning (CoNLL) 2010.
Dmitry Davidov, Ari Rappoport. Automated Translation of Semantic Relationships. COLING 2010.
Dmitry Davidov, Oren Tsur, Ari Rappoport. Enhanced Sentiment Learning Using Twitter Hashtags and Smileys. COLING 2010. _
Shulamit Umansky-Pesin, Roi Reichart, Ari Rappoport. A Multi-Domain Web-Based Algorithm for POS Tagging of Unknown Words. COLING 2010.
Dmitry Davidov, Ari Rappoport. Geo-mining: Discovery of Road and Transport Networks Using Directional Patterns. EMNLP 2009.
Dmitry Davidov, Ari Rappoport. Enhancement of Lexical Concepts Using Cross-lingual Web Mining. EMNLP 2009.
Ram Boukobza, Ari Rappoport. Multi-Word Expression Identification Using Sentence Surface Features. EMNLP 2009.
Omri Abend, Roi Reichart, Ari Rappoport. Unsupervised Argument Identification for Semantic Role Labeling. ACL 2009. _
Roi Reichart, Ari Rappoport. The NVI Clustering Evaluation Measure. Computational Natural Language Learning (CoNLL) 2009.
(Source code of the algorithm is available here.)
(Best Paper Award) Roi Reichart, Ari Rappoport. Sample Selection for Statistical Parsers: Cognitively Driven Algorithms and Evaluation Measures. Computational Natural Language Learning (CoNLL) 2009.
Roi Reichart, Ari Rappoport. Automatic Selection of High Quality Parses Created By a Fully Unsupervised Parser. Computational Natural Language Learning (CoNLL) 2009.
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.
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). _
Dmitry Davidov, Ari Rappoport. Translation and Extension of Concepts Across Languages. EACL 2009.
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.
Dmitry Davidov, Ari Rappoport. Unsupervised Discovery of Generic Relationships Using Pattern Clusters and its Evaluation by Automatically Generated SAT Analogy Questions. ACL 2008. _
Dmitry Davidov, Ari Rappoport. Classification of Semantic Relationships between Nominals Using Pattern Clusters. ACL 2008. _
Vivek Srikumar, Roi Reichart, Mark Sammons, Ari Rappoport, Dan Roth. Extraction of Entailed Semantic Relations Through Syntax-based Comma Resolution. ACL 2008.
Roi Reichart, Katrin Tomanek, Udo Hahn, Ari Rappoport. Multi-Task Active Learning for Linguistic Annotations. ACL 2008. _
Omri Abend, Roi Reichart, Ari Rappoport. A Supervised Algorithm for Verb Disambiguation into VerbNet Classes. COLING 2008.
Roi Reichart, Ari Rappoport. Unsupervised Induction of Labeled Parse Trees by Clustering with Syntactic Features. COLING 2008.
Dmitry Davidov, Ari Rappoport, Moshe Koppel. Fully Unsupervised Discovery of Concept-Specific Relationships by Web Mining. Proceedings, ACL 2007. _
Roi Reichart, Ari Rappoport. An Ensemble Method for Selection of High Quality Parses. ACL 2007.
Roi Reichart, Ari Rappoport. Self-Training for Enhancement and Domain Adaptation of Statistical Parsers Trained on Small Datasets. ACL 2007. _
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. _
Dmitry Davidov, Ari Rappoport. Efficient Unsupervised Discovery of Word Categories Using Symmetric Patterns and High Frequency Words. COLING-ACL 2006. _
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.
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

Rappoport Ari, Spitz Steven, Etzion Michal. One-dimensional selections for feature-based data exchange. Proceedings, Solid Modeling '05, June 2005, MIT. (pdf)
Rappoport Ari, Spitz Steven, Etzion Michal. Two-dimensional selections for feature-based data exchange. Proceedings, Geometric Modeling and Processing (GMP) 2006, July 2006, Pittsburgh, USA. (pdf)
Spitz Steven, Rappoport Ari. Integrated feature-based and geometric CAD data exchange. Proceedings, Solid Modeling '04, June 2004, Genova, Italy, ACM Press. (pdf)
Rappoport Ari. An architecture for universal CAD data exchange. Proceedings, Solid Modeling '03, June 2003, Seattle, Washington, ACM Press. (pdf)

The Voronoi Graph (Medial Axis)

Etzion Michal, Rappoport Ari. Computing Voronoi skeletons of a 3-D polyhedron by space subdivision. Computational Geometry: Theory and Applications, 21(3):87-120, March 2002. (pdf)
Sheffer Alla, Etzion Michal, Rappoport Ari, Bercovier Michel. Hexahedral mesh generation using the embedded Voronoi graph. Proceedings, Seventh International Meshing Roundtable, pp. 347-364, 1998. (pdf)
Etzion Michal, Rappoport Ari. Computing the Voronoi diagram of a 3-D polyhedron by separate computation of its symbolic and geometric parts. Proceedings, Fifth ACM/Siggraph Symposium on Solid Modeling and Applications (Solid Modeling '99), ACM Press, 1999.
Etzion Michal, Rappoport Ari. A boundary sampling algorithm for computing the Voronoi graph of a 2-D polygon. Technical Report, Institute of Computer Science, The Hebrew University, 1996.

Interactive Rendering

Ofek Eyal, Rappoport Ari. Interactive reflections on curved objects. Proceedings of Siggraph 98. In Computer Graphics Proceedings, Annual Conference Series, 1998, ACM SIGGRAPH, pp. 333-342.
Rappoport Ari, Spitz Steven. Interactive Boolean operations for conceptual design of 3-D solids. Proceedings of Siggraph 97. In Computer Graphics Proceedings, Annual Conference Series, 1997, ACM SIGGRAPH, pp. 269-278. (pdf)

Generative and Declarative Modeling

Rappoport Ari. The Generic Geometric Complex (GGC): a modeling scheme for families of decomposed pointsets. Proceedings, Fourth ACM/Siggraph Symposium on Solid Modeling and Applications (Solid Modeling '97), May 1997, Atlanta, ACM Press, pp. 19-30. (pdf)
Rappoport Ari. Breps as displayable-selectable models in interactive design of families of geometric objects. Geometric Modeling: Theory and Practice, Strasser, Klein, Rau, (Eds), Springer-Verlag, 1997, pp. 206-225 (proceedings, Theory and Practice of Geometric Modeling (Blaubeuren II), Tübingen, Germany, October 1996.) (pdf)
Rappoport Ari. Parametric and declarative modeling of families of geometric objects. Presented at the IFIP Workshop on Geometric Modeling in CAD, Airlie, VA, May 1996. Abstract only.
Rappoport Ari. Geometric modeling: a new fundamental framework and its practical implications. Proceedings, Third ACM/Siggraph Symposium on Solid Modeling and Applications (Solid Modeling '95), May 1995, Salt Lake City, ACM Press, pp. 31-42.
Hel-Or Yaacov, Rappoport Ari, Werman Michael. Relaxed parametric design with probabilistic constraints. Computer-Aided Design, 26(6):426-434, 1994. Also: proceedings, Second ACM/Siggraph Symposium on Solid Modeling and Applications, May 1993, Montreal, ACM Press, pp. 261-270. (pdf)
Emmerik, M.J.G. Maarten (van), Rappoport Ari, Rossignac Jarek. Simplifying interactive design of solid models: a hypertext approach. The Visual Computer: an International Journal of Computer Graphics, 9:239-254, 1993.
Rappoport Ari. A scheme for single instance representation in hierarchical assembly graphs. Falcidieno, B., Kunii T.L. (eds), Geometric Modeling in Computer Graphics, pp. 213-224, Springer, 1993 (IFIP Conference on Geometric Modeling in Computer Graphics, Genova, Italy, June 1993) (An updated version is available). (pdf of the updated version.)

Representations and Algorithms for Polygons and Polyhedra

Etzion Michal, Rappoport Ari. On compatible star decompositions of simple polygons. IEEE Transactions on Visualization and Computer Graphics, 3(1):87-95, 1997.
Rappoport Ari. The extended convex differences tree (ECDT) representation for n-dimensional polyhedra. Intl. Journal of Computational Geometry and Applications, 1(3):227-241, 1991. Also: proceedings, First ACM/Siggraph Symposium on Solid Modeling Foundations and CAD/CAM Applications, June 1991, Austin, ACM Press, pp. 139-148.
Rappoport Ari. An efficient adaptive algorithm for constructing the convex differences tree of a simple polygon. Computer Graphics Forum, 11(4):235-240, 1992.
Rappoport Ari. An efficient algorithm for line and polygon clipping. The Visual Computer: an International Journal of Computer Graphics, 7(1):19-28, 1991.
Rappoport Ari. Using convex differences for hierarchical representations of polygonal maps. Graphics Interface 90, Halifax, Canada, May 1990, pp. 183-189.

Digital Typography

Shamir Ariel, Rappoport Ari. Compacting Oriental Fonts by Optimizing Parametric Elements. The Visual Computer, 15(6):302-318, 1999.
Shamir Ariel, Rappoport Ari. Dynamic typography. Technical Report, Institute of Computer Science, The Hebrew University, 1997.
Shamir Ariel, Rappoport Ari. Feature-based design of fonts using constraints. Electronic Publishing, Artistic Imaging and Digital Typography, Proc. of the EP'98 and RIDT'98 Conferences, St Malo, March 30 - April 3, 1998. Eds. Roger D. Hersch, Jacques Andre, Heather Brown, LNCS, Springer Verlag, 1998. Presented at Raster Imaging and Digital Typography 1998 (RIDT '98), April 1998.
Shamir Ariel, Rappoport Ari. Extraction of typographic elements from outline representations of fonts. Computer Graphics Forum, 15(3):259-268, 1996 (proceedings, Eurographics '96). (pdf)
Shamir Ariel, Rappoport Ari. Quality enhancements of digital outline fonts. Computers and Graphics, Special Issue on Graphics in Electronic Printing and Publishing, 21(6):713-725, 1997.

Curves, Surfaces and Volumes

Rappoport Ari, Sheffer Alla, Bercovier Michel. Volume-preserving free-form solids. IEEE Transactions on Visualization and Computer Graphics, 2(1):19-27, 1996. Also: proceedings, Third ACM/Siggraph Symposium on Solid Modeling and Applications (Solid Modeling '95), May 1995, Salt Lake City, ACM Press, pp. 361-372.
Rappoport Ari, Hel-Or Yaacov, Werman Michael. Interactive design of smooth objects using probabilistic point constraints. ACM Transactions on Graphics, 13(2):156-176, 1994.
Rappoport Ari. Rendering curves and surfaces with hybrid subdivision and forward differencing. ACM Transactions on Graphics, 10(4):323-341, October 1991.

Morphing and Deformations

Shapira Michal, Rappoport Ari. Shape blending using the star-skeleton representation. IEEE Computer Graphics and Applications, 15(2):44-50, March 1995. (pdf)
Borrel Paul, Rappoport Ari. Simple constrained deformations for geometric modeling and interactive design. ACM Transactions on Graphics, 13(2):137-155, 1994. (pdf)

Modeling and Rendering from Images and Image Sequences

Lischinski Dani, Rappoport Ari. Image-based rendering for non-diffuse synthetic scenes. Proceedings, Ninth Eurographics Workshop on Rendering, 1998, pp. 301-314. (pdf)
Zakai Yaron, Rappoport Ari. Three-dimensional modeling and effects on still images. Computer Graphics Forum, 15(3):3-10, 1996 (proceedings, Eurographics '96).
Ofek Eyal, Shilat Erez, Rappoport Ari, Werman Michael. Multiresolution textures from image sequences. IEEE Computer Graphics and Applications, 17(2):18-29, March 1997. Also Technical Report, Institute of Computer Science, The Hebrew University, 1994.

User Interface

Rappoport Ari. Direct manipulation devices for the design of geometric constraint networks. Magnenat-Thalmann, N., Thalmann, D. (eds), Communicating with Virtual Worlds, pp. 294-305, Springer, 1993 (proceedings, Computer Graphics International '93, Lausanne, June 1993.)
Rappoport Ari, Emmerik M.J.G. Maarten (van). User interface devices for rapid and exact number specification. ACM Transactions on Graphics, 12(4):348-354, 1993.

Contact

ari.rappoport@mail.huji.ac.il. The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Office B413, Rothberg Building, Edmond J. Safra Campus at Givat Ram. Phone and Fax: +972-2-549-4564.

Students

Graduate (PhD, MSc) and Amirim

Effi Levi (PhD)

Alumni

Elior Sulem (2019, PhD)
Daniel Hershcovich (2019, PhD)
Roy Schwartz (2016, PhD)
Omri Abend (2013, PhD)
Oren Tsur (2013, PhD)
Roi Reichart (2010, PhD)
Dmitry Davidov (1975-2010) (2010, PhD)
Eyal Ofek (2001, PhD)
Arik Shamir (2000, PhD)
Michal Etzion (1999, PhD)
Gal Harari (2022, MSc)
Uri Berger (2021, MSc)
Adi Bitan (2019, MSc)
Michael Latar (2019, MSc)
Zohar Vittenberg (2019, MSc)
Saggy Herman (2017, MSc)
Dana Rubinstein (2015, MSc)
Elior Sulem (2014, MSc)
Adi Littman (2013, MSc)
Amit Beka (2013, MSc)
Eran Bringer (2011, MSc)
Daphna Shezaf (2010, MSc)
Shulamit Umansky-Pesin (2010, MSc)
Ram Boukobza (2010, MSc)
Inna Zusman (with Malka Rappaport-Hovav, 2009, MSc)
Elad Dinur (2009, MSc)
Shlomit Tshuva (2007, MSc)
Tsahi Levent-Levi (2006, MSc)
Gil Asherie (2006, MSc)
Vera Sheinman (2005, MSc)
Elisheva Werner-Reiss (2000, MSc)
Daniel Goldschmidt (1999, MSc)
Yoav Samet (1996, MSc)
Yaron Zakai (1996, MSc)
Gidi Etzion (1996, MSc)
Alla Sheffer (with Michel Bercovier, 1995, MSc)
Michal Shapira (1994, MSc)
Evgeny Drapkin (1993, MSc)
Roy Schwartz (2008, Amirim)
Omri Abend (2006, Amirim)
Uri Cohen (2005, Amirim)
Steven Spitz (1995, Amirim)
Ephi Sachs (with main supervisor Ido Dagan, 2008, MSc)
Shachar Mirkin (with main supervisor Ido Dagan, 2006, MSc)

Teaching

Large Software Projects ("Tohna Begadol") // 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 a co-founder of MagniLEARN, an online language learning company. We provide English learning software based on state-of-the-art concepts in neuroscience, cognitive science, applied linguistics and machine learning. 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 NLP, 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.