^November December – 2007 ^January

The field of Augmentative and Alternative Communication (AAC) is concerned with studying methods of communication that can be added to natural communication (speech and writing), especially when an individual lacks some of the skills to achieve it. Natural language processing techniques have been used for AAC applications to enhance the rate of communication and extend the range of expressions that can be generated. The key applications include message generation, abbreviation expansion, word prediction and text simplification. In my talk I will present the world of AAC, the usage of NLP within AAC, and specifically natural language generation systems including the one developed in BGU.

The most popular object-oriented programming (OOP) languages nowadays - Java, C++, C# - are statically-typed and based on a static model. They do not allow to manipulate their classes at run-time. As a result, many programmers view OOP as a methodology with limited flexibility and expressiveness. OOP languages do not have to be static. Several new scripting languages break this rule by implementing a highly dynamic and flexible version of OOP. These are dynamically-typed languages that allow to manipulate objects and classes at run-time. This ability gives a lot of flexibility to the programmer, and those languages are gaining much popularity.

One of the more impressive and useful usages of this approach is the implementation of a meta-classes system in Python. Meta-classes are classes that create other classes as their instances. Using meta-classes lets programmers implement design patterns and aspect-oriented programming by using the programming language itself, giving a higher level of expressiveness and code re-use. In this talk I will give a short introduction to those new approaches in OOP, and present meta-OOP programming in Python, with its powers and problems.

We study the round complexity of various cryptographic protocols. Our main result is a tight lower bound on the round complexity of any fully-black-box construction of a statistically-hiding commitment scheme from one-way permutations, and even from trapdoor permutations. This lower bound matches the round complexity of the statistically-hiding commitment scheme due to Naor, Ostrovsky, Venkatesan and Yung (CRYPTO '92). As a corollary, we derive similar tight lower bounds for several other cryptographic protocols, such as single-server private information retrieval, interactive hashing, and oblivious transfer that guarantees statistical security for one of the parties. Our techniques extend the collision-finding oracle due to Simon (EUROCRYPT '98) to the setting of interactive protocols (our extension also implies an alternative proof for the main property of the original oracle). In addition, we substantially extend the reconstruction paradigm of Gennaro and Trevisan (FOCS `00). In both cases, our extensions are quite delicate and may be found useful in proving additional black-box separation results. Joint work with Jonathan J. Hoch, Gil Segev and Omer Reingold