Building Lexical Cognitive Networks for Web Corpora with Application to Semantic Similarity Computation and Affective Text Analysis
Prof. Alexandros Potamianos
Technical University of Crete, Greece
Monday, October 29
2:00 PM, ICSI Lecture Hall
Abstract
We investigate language-agnostic algorithms for the construction of unsupervised distributional semantic models using web-harvested corpora. A corpus is created from web document snippets and the relevant semantic similarity statistics are encoded in a semantic network. We propose the notion of semantic neighborhoods that are defined using co-occurrence or context similarity features.Three neighborhood-based similarity metrics are proposed, motivated by the hypotheses of attributional and maximum sense similarity. The lexical networks and semantic distances are motivated by cognitive considerations (associative networks and lexical priming). The proposed metrics are evaluated against human similarity ratings achieving state-of-the-art results. The proposed semantic similarity metrics are applied to affective modeling of text. Continuous valence ratings are estimated for unseen words using the underlying assumption that semantic similarity implies affective similarity. Starting from a set of manually annotated words, a linear affective model is trained using the least mean squares algorithm followed by feature selection. We then propose linear and non-linear fusion schemes for investigating how lexical valence scores can be combined to produce sentence-level scores, as well as, extend the lexical similarity model to groups of words (compounds). Evaluation on affective text tasks (e.g., polarity recognition ) show significant performance improvement compared to the state of the art.
Speaker Bio
Alexandros Potamianos received the Diploma in Electrical and Computer Engineering from the National Technical University of Athens, Greece in 1990. He received the M.S and Ph.D. degrees in Engineering Sciences from Harvard University, Cambridge, MA, USA in 1991 and 1995, respectively. He received the M.B.A. degree from Stern School of Business, NYU in 2002.From 1991 to June 1993 he was a research assistant at the Robotics Lab, Harvard University. From 1993 to 1995 he was a research assistant at the Digital Signal Processing Lab at Georgia Tech. From 1995 to 1999 he was a Senior Technical Staff Member at the Speech and Image Processing Lab, AT&T Shannon Labs, Florham Park, NJ. From 1999 to 2002 he was a Technical Staff Member and Technical Supervisor at the Multimedia Communications Lab at Bell Labs, Lucent Technologies, Murray Hill, NJ. From 1999 to 2001 he was an adjunct Assistant Professor at the Department of Electrical Engineering of Columbia University, New York, NY. In the spring of 2003, he joined the Department of Electronics and Computer Engineering at the Technical University of Crete, Chania, Greece as an associate professor.His current research interests include speech processing, analysis, synthesis and recognition, dialog and multi-modal systems, nonlinear signal processing, natural language understanding, artificial intelligence and multimodal child-computer interaction. Prof. Potamianos has authored or co-authored over ninety papers in professional journals and conferences. He is the co-author of the paper "Creating conversational interfaces for children" that received a 2005 IEEE Signal Processing Society Best Paper Award. He is the co-editor of the book "Multimodal Processing and Interaction: Audio, Video, Text", Springer, 2008.