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.

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

Tile behavioral specification o1' an object-oriented grammar model is consklcrcd. The model is based on ftfll lexicalization, head-orientation via valency constraints and dependency relations, inheritance as a means for non-rednmlant lexicon spccitication, and conct, rrcncy of computation. The compntation model relies upon the actor l)aradigm, with concnrrcncy entering throngh asyll- ;hronous message passing Ix:(ween actors. In particular, we here elaborate on principles of how the global behavior of a lexically distribute_xl grammar anti its corresponding parser can be speeificd in terms of event type networks and event networks, rcsp.

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. 2 1

A framework for concurrent, object-oriented natural language parsing is introduced. The underlying grammar model is fully lexicalized, headdriven, dependency-oriented, and structured along multiple inheritance hierarchies. The computation model relies upon the actor paradigm, with concurrency entering through asynchronous message passing. Protocols for establishing basic dependency relations and for coping with structural ambiguities and text-level anaphora are considered.