i 
Breadth and Depth of Semantic Lexicons 
Introduction - Notes on the Workshop 
Evelyne Viegas 
Computing Research Laboratory 
New Mexico State University 
Las Cruces, NM 88003 
viegas@crl.nmsu.edu 
Introduction 
Building semantic lexicons is a very time consuming task. Efficient large-scale acquisition and 
representation of lexical knowledge will be greatly aided by capturing regularities in the lexicon. 
Two main issues present themselves: 
a) treatment of lexical ambiguity and 
b) lexical rules as a conceptual tool for controlled proliferation of entries. 
Whereas the former has been regarded as a topical issue for quite some time, the latter is only 
now receiving its due attention. This workshop will concentrate on lexical rules as a regulator of 
breadth and depth of the lexicons. Lexical rules are known under a variety of names, e.g., Leech's 
(1981) "semantic transfer rules," "lexical implication rules" of Ostler and Atkins (1991) and others. 
They are also addressed in the framework of such theories as the generative lexicon of Pustejovsky 
(1995). Such linguistic frameworks as LFG and HPSG have also used the concept, albeit in a 
different sense and for a different purpose. At the same time, theoretical accounts of the use of 
lexical rules (such as, for instance, preemption or blocking) are rather too general and underspec- 
ified to support actual processing. The workshop will stress issues connected with the practical 
application of lexical rules: when to apply the rules, how the rules influence system design, how 
to reexamine and adjust the theoretically posited rules in view of practical needs and evidence. 
Another central issue for the workshop will be large-scale acquisition of computational-semantic 
lexicons for practical applications. We are mainly interested in examining the following trade-offs: 
the coverage vs.the depth of existing semantic lexicons vs. the effort involved in building them. 
The workshop is intended for researchers in computational linguistics, artificial intelligence, 
psycholinguistics or other fields who have been working in lexical semantics and large-scale lexical 
knowledge acquisition. 
Notes on the Workshop 
The workshop was organized around three main themes reflecting the topic addressed in the papers 
we received: 
a large scale acquisition of semantic lexicons using a corpus-based approach 
b development of micro-theories addressing various topics and phenomena such as, word sense 
disambiguation - nominal compounds - deverbal adjectives - inflectional morphology 
c position papers discussing the status of lexical rules or focusing on the dynamic aspect of 
knowledge sources and of cognitive processes 
Some (though not necessarily all) specific questions suggested for discussion include: 
What are the different types of lexical rules which should be considered in the building of 
computational lexicons (inflectional and derivational morphology, verbal diatheses, regular 
word-sense shifts, other) 
2 When should the rules be applied (run-time, load-time, acquisition, other) 
How to evaluate the cost-efficiency of the acquisition effort against the utility of the resulting 
lexicons. How could we characterize an NLP system along the dimensions of size, corpus 
coverage, and depth. 
4 Analyses of appropriate types of inheritance for different lexical rules. 
5 The use of lexical underspecification (and contextual word-use grounding) as a partial alter- 
native to lexical rules. 
In order to facilitate interaction between participants, a pre-workshop mailing list was estab- 
lished. Papers were also available to all participants a month prior to the event in Santa Cruz 
at http://crl.nmsu.edu/lex-rule. This web site will remain available after the workshop for 
further discussions. 

References 
Geoffrey Leech (1991) Semantics, Cambridge: Cambridge University Press. 
Nicholas Ostler and B. T. S. Atkins (1992) Predictable meaning shift: Some linguistic properties of 
lexical implication rules. In J. Pustejovsky and S. Bergler (eds), Lexical Semantics and Knowledge 
Representation. Berlin: Springer. 
James Pustejovsky (1995) The Generative Lexicon. Cambridge, MA: MIT Press. 
