This paper consists of two parts. The first part discusses commonsense knowledge about events as manifested in language. Three kinds of knowledge are identified: compositional, durational, and aspectual. Compositional knowledge concerns internal structuring of events into preparatory, initial, main (the body), final, and resulting stages. Durational knowledge concerns durational relations between events and stages of the same event. Durational knowledge can be expressed as qualitative dependencies among the parameters of the event and as its time scale. The notion of time scale is introduced and related to shared cyclical events (time units). In discussing

The ParseTalk model of concurrent, object-oriented natural language parsing is introduced. It builds upon the complete lexical distribution of grammatical knowledge and incorporates inheritance mechanisms in order to express generalizations over sets of lexical items. The grammar model integrates declarative well-formedness criteria constraining linguistic relations between heads and modifiers, and procedural specifications of the communication protocol for establishing these relations. The parser's computation model relies upon the actor paradigm, with concurrency entering through asynchronous message passing. We consider various extensions of the basic actor model as required for distributed natural language understanding and elaborate on the semantics of the actor computation model in terms of event type networks (a graph representation for actor grammar specifications) and event networks (graphs which represent the actor parser's behavior). Besides theoretical claims, we present an interactive grammar/parser workbench, a graphical development environment with various types of browsers, tracers, inspectors and debuggers that has been adapted to the requirements of large-scale grammar engineering in a distributed, object-oriented specification and programming framework.

We formalize and extend the contribution model of Clark and Schaefer (1987, 1989) so that it can be represented computationally; we then present a method for combining the turns of two individual agents into one incrementally determined, coherent representation of the processes of dialog. This representation is intended to approximate what a participant might represent about the dialog so far, for the immediate purpose of referring, making contextual inferences, and repairing problems of understanding, as well as for the longer term purpose of storing the products of dialog in memory. Such an approach, we argue, is necessary for enabling a computer-based partner to converse in a way that seems natural to a human partner. Introduction Dialog is a collective activity that is managed in real time by agents with limited attentional, computational, and knowledge resources. Even when two agents are rational and cooperative, inhabit the same location, speak the same language, sh...

We introduce two abstraction mechanisms for streamlining the process of semantic interpretation. Configurational

Abstract. A grammar model for concurrent, object-oriented natural language parsing is introduced. Complete lexical distribution of grammatical knowledge is achieved building upon the head-oriented notions of valency and dependency, while inheritance mechanisms are used to capture lexical generalizations. The underlying concurrent computation model relies upon the actor paradigm. We consider message passing protocols for establishing dependency relations and ambiguity handling. 1

We describe a compiler which translates a set of hpsg lexical rules and their interaction into definite relations used to constrain lexical entries. The compiler ensures automatic transfer of properties unchanged by a lexical rule. Thus an operational semantics for the full lexical rule mechanism as used in HPSG linguistics is provided. Program transformation techniques are used to advance the resulting encoding. The final output constitutes a computational counterpart of the linguistic generalizations captured by lexical rules and allows "on the fly" application. Keywords: lexical rules, hpsg, off-line compilation, program transformation. 1 Introduction In the paradigm of hpsg, lexical rules (henceforth lr) have become one of the key mechanisms used in current analysis. Among logicians and computational linguists, lrs have been far less popular. The intuitive idea behind lrs is based on notions such as matching, copying, and automatic transfer of the properties unchanged by a lr, ...

Multi-action utterances convey critical information about agents' beliefs and intentions with respect to the actions they talk about or perform. Two such utterances may, for example, describe the same actions while the speakers of these utterances hold beliefs about these actions that are diametrically opposed. Hence, for a language interpretation system to understand multi-action utterances, it must be able (1) to determine the actions that are described and the ways in which they are related, and (2) to draw appropriate inferences about the agents' mental states with respect to these actions and action relations. This thesis investigates the semantics of two particular multi-action constructions: utterances with means clauses and utterances with rationale clauses. These classes of utterances are of interest not only as exemplars of multi-action utterances, but also because of the subtle differences in information that can be felicitously inferred from their use. Their meaning is show...

Montague's famous characterization of the homomorphic relation between syntax and semantics naturally gives way in computational applications to constraint-based formulations. This was originally motivated by the close harmony it provides with syntax, which is universally processed in a constraint-based fashion. Employing the same processing discipline in syntax and semantics allows that their processing (and indeed other processing) can be as tightly coupled as one wishes -- indeed, there needn't be any fundamental distinction between them at all. In this paper, we point out several advantages of the constraint-based view of semantics processing over standard views. These include (i) the opportunity to incorporate nonsyntactic constraints on semantics, such as those arising from phonology and context; (ii) the opportunity to formulate principles which generalize over syntax and semantics, such as those found in head-driven phrase structure grammar; (iii) a characterization of semantic ...

We propose a semantics for locative expressions such as near Jones or west of Denver, an important subsystem for NLP applications. Locative expressions denote regions of space, and serve as arguments to predicates, locating objects and events spatially. Since simple locatives occupy argument positions, they do NOT participate in scope ambiguities-- pace one common view, which sees locatives as logical operators. Our proposal justifies common representational practice in computational linguistics, accounting for how locative expressions function anaphorically, and explaining a wide range of inference involving locatives. We further demonstrate how the argument analysis may accommodate multiple locative arguments in a single predicate. The analysis is implemented for use in a database query application.

The CODER (COmposite Document Expert/extended/effective Retrieval) project is an investigation of the applicability of artificial intelligence techniques to the information retrieval task of analyzing, storing, and retrieving heterogeneous collections of “composite documents.” In order to support some of the processing desired, and to allow experimentation in information retrieval and natural language processing, a lexicon was constructed from the machine readable Collins Dictionary of the English Language. After giving background, motivation, and a survey of related work, the Collins lexicon is discussed. Following is a description of the conversion process, the format of the resulting Prolog database, and characteristics of the dictionary and relations. To illustrate what is present and to explain how it relates to the files produced from Webster's Seventh New Collegiate Dictionary, a number of comparative charts are given. Finally, a grammar for adverb definitions is presented, together with a description of defining formula that usually indicate the type of the adverb. Ultimately it is hoped that definitions for adverbs and other words will be parsed so that the relational lexicon being constructed will include many additional relationships and other knowledge about words and their usage.