PDF《and Beyond》

s thesis neatly summarize the broad interdisciplinar- ity which characterized his approach to his thesis, and throughout his research career. The ?rst is from the Preface: There are four kinds of thesis in cognitive science: formal, empirical, program- based and discursive. What sort was mine to be? ... I look round in delight to ?nd [my thesis] does a little bit of all the things a cognitive science thesis might do! [19, p. vi] while the second is in the introduction to his discussion of methodology: We take the study of the lexicon to be intimately related to the study of the mind ... . For an understanding of the lexicon, the contributing disciplines are lexicography, psycholinguistics and theoretical, computational and corpus linguistics. [19, p. 4] The distinctions made in the ?rst of these quotes provide a neat framework to dis- cuss the content of the thesis in more detail. Adam'

s own starting point was empirical: in two studies he demonstrated ?rst that the range and type of sense distinctions found in a typical dictionary de?ed any simple systematic classi?cation, and second that the so-called bank model of word senses (where senses from dictionaries were considered to be distinct and easy to enumerate and match to textual instances) did not in general re?ect actual dictionary sense distinctions (which tend to overlap). A key practical con- sequence of this is that the then-current NLP WSD systems which assumed the bank model could never achieve the highest levels of performance in sense matching tasks. From this practical exploration, Adam moved to more discursive territory. He ex- plored the basis on which lexicographers decide which sense distinctions appear in dic- tionaries, and introduced an informal criterion to characterize it C the Suf?ciently Fre- quent and Insuf?ciently Predicable (SFIP) condition, which essentially favors senses which are both common and non-obvious. However he noted that while this criterion had empirical validity as a way of circumscribing polysemy in dictionaries, it did not offer any clear understanding of the nature of polysemy itself. He argued that this is because polysemy is not a '

natural kind'

but rather a cover term for several other more speci?c but distinct phenomena: homonymy (the bank model), alternation (systematic usage differences), collocation (lexically contextualized usage) and analogy. This characterization led into the formal/program-based contribution (which in the spirit of logic-based programming paradigms collapse into one) of his thesis, for which he developed two formal descriptions of lexical alternations using the inheritance-based lexical description language DATR. His aim was to demonstrate that while on ?rst sight much of the evidence surrounding polysemy seemed unruly and arbitrary, it was nev- ertheless possible, with a suf?ciently expressive formal language, to characterize sub- stantial aspects of the problem in a formal, computationally tractable way. Adam'

s own summary of the key contributions of his work were typically succinct: The thesis makes three principal claims, one empirical, one theoretical, and one formal and computational. The ?rst is that the Bank Model is fatally ?awed. The second is that polysemy is a concept at a crossroads, which must be un- derstood in terms of its relation to homonymy, alternations, collocations and analogy. The third is that many of the phenomena falling under the name of polysemy can be given a concise formal description in a manner ... which is well-suited to computational applications. [19, p. 8] With the bene?t of hindsight, we can see in this thesis many of the key ideas which Adam developed over his career. In particular, the beginnings of his empirical, usage- based approach to understanding lexical behaviour, his interest in lexicography and support for the lexicographic process, and his ideas for improving the methodology and development of computational WSD systems probably ?rst came together as the identi?able start of his subsequent journey in [20], and will all feature prominently in the remainder of this review. What is perhaps more surprising from our present perspective is his advocacy of formal approaches to achieve some of these goals, in part........