While automatic text summarization is an area that has received a great deal of attention in recent research, the problem of efficiency in this task has not been frequently addressed. When the size and quantity of documents available on the Internet and from other sources are considered, the need for a highly efficient tool that produces usable summaries is clear. We present a linear-time algorithm for lexical chain computation. The algorithm makes lexical chains a computationally feasible candidate as an intermediate representation for automatic text summarization. A method for evaluating lexical chains as an intermediate step in summarization is also presented and carried out. Such an evaluation was heretofore not possible because of the computational complexity of previous lexical chains algorithms.

This report is the first in a series of investigations designed to test a theory identifying the effects of conversational trade-offs between selected maxims on public attitudes toward augmentative and alternative communication (AAC) system users and their communication. In the current study, the trade-offs between the relevance of a prestored message and its speed of delivery were examined. Participating were 96 sales clerks. Twelve scripted videotaped conversational conditions, involving an AAC customer and a clerk at a checkout counter, were used to manipulate message relevance, speed of message delivery, and participant/AAC user gender. Following each assigned viewing, participants completed a questionnaire designed to assess their attitudes toward the AAC user and his or her communication. Significantly higher mean ratings were found for the conditions involving the slowly delivered relevant messages (both preceded by a conversational floorholder and without a floorholder) when compared to the quickly delivered partly relevant message condition. In addition, the condition involving the slowly delivered relevant message with a floorholder yielded significantly higher mean ratings than that without the floorholder. There was no effect for participant/user gender. Modifications of the theory and technological implications are discussed.

This paper reports on the recognition component of an intelligent tutoring system that is designed to help foreign language speakers learn standard English. The system models the grammar of the learner, with this instantiation of the system tailored to signers of American Sign Language (ASL). We discuss the theoretical motivations for the system, various difficulties that have been encountered in the implementation, as well as the methods we have used to overcome these problems. Our method of capturing ungrammaticalities involves using malrules (also called 'error productions'). However, the straightforward addition of some mal-rules causes significant performance problems with the parser. For instance, the ASL population has a strong tendency to drop pronouns and the auxiliary verb 'to be'. Being able to account for these as sentences results in an explosion in the number of possible parses for each sentence. This explosion, left unchecked, greatly hampers the performance of the system. We discuss how this is handled by taking into account expectations from the specific population (some of which are captured in our unique user model). The different representations of lexical items at various points in the acquisition process are modeled by using mal-rules, which obviates the need for multiple lexicons. The grammar is evaluated on its ability to correctly diagnose agreement problems in actual sentences produced by ASL native speakers.

This report is the second in a series of investigations designed to develop a working model identifying the effects of trade-offs between selected conversational maxims on public attitudes toward augmentative and alternative communication (AAC) system users and their communication. In the current study, tradeoffs between the informativeness of a prestored message and its speed of delivery were examined. A total of 96 salesclerks participated. Sixteen scripted, videotaped conversational conditions, involving an AAC customer and a clerk at a checkout counter, were used to manipulate message informativeness and speed of message delivery. Following each assigned viewing, participants completed a questionnaire designed to assess their attitudes toward the AAC user and his or her communication. The conditions involving (a) the quickly delivered message with excessive information, (b) the slowly delivered message with adequate information preceded by a "floorholder," and (c) the slowly delivered message with adequate information without a floorholder were rated higher than (d) the quickly delivered message with inadequate information. There was no main effect for participant or AAC user gender. Implications regarding a model of conversational trade-offs and technological applications are discussed.