AT&T Labs

About: AT&T Labs is a based out in . It is known for research contribution in the topics: Network packet & The Internet. The organization has 1879 authors who have published 5595 publications receiving 483151 citations.

The power of amnesia: learning probabilistic automata with variable memory length

Abstract: We propose and analyze a distribution learning algorithm for variable memory length Markov processes. These processes can be described by a subclass of probabilistic finite automata which we name Probabilistic Suffix Automata (PSA). Though hardness results are known for learning distributions generated by general probabilistic automata, we prove that the algorithm we present can efficiently learn distributions generated by PSAs. In particular, we show that for any target PSA, the KL-divergence between the distribution generated by the target and the distribution generated by the hypothesis the learning algorithm outputs, can be made small with high confidence in polynomial time and sample complexity. The learning algorithm is motivated by applications in human-machine interaction. Here we present two applications of the algorithm. In the first one we apply the algorithm in order to construct a model of the English language, and use this model to correct corrupted text. In the second application we construct a simple stochastic model for E.coli DNA.

Rapid ethnography: time deepening strategies for HCI field research

Abstract: Field research methods are useful in the many aspects of Human-Computer Interaction research, including gathering user requirements, understanding and developing user models, and new product evaluation and iterative design. Due to increasingly short product realization cycles, there has been growing interestth in more time efficient methods, including rapid prototyping methods and various usability inspection techniques. This paper will introduce "rapid ethnography," which is a collection of field methods intended to provide a reasonable understanding of users and their activities given significant time pressures and limited time in the field.. The core elements include limiting or constraining the research focus and scope, using key informants, capturing rich field data by using multiple observers and interactive observation techniques, and collaborative qualitative data analysis. A short case study illustrating the important characteristics of rapid ethnography will also be presented.

PARADISE: A Framework for Evaluating Spoken Dialogue Agents

Abstract: This paper presents PARADISE (PARAdigm for DIalogue System Evaluation), a general framework for evaluating spoken dialogue agents. The framework decouples task requirements from an agent's dialogue behaviors, supports comparisons among dialogue strategies, enables the calculation of performance over subdialogues and whole dialogues, specifies the relative contribution of various factors to performance, and makes it possible to compare agents performing different tasks by normalizing for task complexity.

Characteristics of scalability and their impact on performance

Abstract: is a desirable attribute of a network, system, or process. Poor scalability can result in poor system performance, necessitating the reengineering or duplication of systems. While scalability is valued, its characteristics and the characteristics that undermine it are usually only apparent from the context. Here, we attempt to define different aspects of scalability, such as structural scalability and load scalability. Structural scalability is the ability of a system to expand in a chosen dimension without major modifications to its architecture. Load scalability is the ability of a system to perform gracefully as the offered traffic increases. It is argued that systems with poor load scalability may exhibit it because they repeatedly engage in wasteful activity, because they are encumbered with poor scheduling algorithms, because they cannot fully take advantage of parallelism, or because they are algorithmically inefficient. We qualitatively illustrate these concepts with classical examples from the literature of operating systems and local area networks, as well as an example of our own. Some of these are accompanied by rudimentary delay analysis.

Fair exchange with a semi-trusted third party (extended abstract)

Abstract: We present new protocols for two parties to exchange documents with fairness, i.e., such that no party can gain an advantage by quitting prematurely or otherwise misbehaving. We use a third party that is L‘semi-trusted”, in the sense that it may misbehave on its own but will not conspire with either of the main parties. In our solutions, disruption by any one of the three parties will not allow the disrupter gain any useful new information about the documents. Our solutions are efficient and can be based on any of several cryptographic assumptions (e.g., factoring, discrete log, graph isomorpbism). We also discuss the application of our techniques to electronic commerce protocols to achieve fair payment.