Methods of semantic interpretation

Recent development of artificial intelligence (AI) has push the discussion of polysemy onto the front stage \brought considerably much more attention to this formerly neglected phenomenon We believe that it is acceptable for a semantics to be based on the notion of word sense as used by traditional lexicography in constructing dictionaries. To put the matter another way, the inability of programs to cope with lexical ambiguity was a major reason for the failure of early computational linguistics tasks like machine translation.

Yet it does follow from that failure that the lexical ambiguity distinguished by conventional dictionaries has any real significance for e. g. in the claim that a word such as play has eight senses that are then distinguished and described? The point can perhaps be put most clearly by considering the suggestion that there never was lexical ambiguity until dictionaries were written in roughly the form we now have them, and that lexical ambiguity is no more or less than a product of scholarship: a social product, in other words.

Translation between languages, as well as more mundane understanding tasks has been going along for millenia before such scholarly products and therefore cannot require them. This suggestion would be very much to the taste of certain formal semanticists who have never found the idea of lexical ambiguity interesting or important. For them it is a peripheral phenomenon, one that can be dealt with by subscripting symbols as play1, play2, etc.

And claiming that there is , in any case; no real ambiguity in the world itself: Another problem to be faced by those who want to construct a lexical ambiguity data base, or customize an existing one is the arbitrariness in the selection of senses for a word: different dictionaries may give 1, 2, 7, 34, or 87 senses for a single word and at first glance it seems that they cannot all be right. It's a mapping problem.

This arbitrariness does not only appear between different dictionaries in their different sense ranges for the same word-it is also observable within a single dictionary when the sense-distinctions made for the definition of a world do not match the use of that word in the definitions of other words in the dictionary. Worse yet, different dictionaries will segment usage into senses for a given word in non-comparable ways… In short, they fail to agree but none of them is wrong.

Preliminary remarks An important source of ambiguity in natural language is the polysemy of lexical elements, and this is certainly one of the most intricate problems of semantic description. It is easy to observe that many words in many sentences can be understood quite differently, but it is notoriously difficult to give a systematic account of this phenomenon in a description of a language. Bloomfield was so aware of the problem that he despaired of any satisfactory treatment of semantics.

I will restrict myself in this paper to some preliminary observations on the polysemy problem, in connection with the description of ambiguity. Let me point out at the beginning that 'polysemous' and 'ambiguous' will not be regarded here as equivalent notion. In the field of lexical description also, terms like 'polysemous', 'ambiguous', and 'having more than one interpretation' are often used as if they were interchangeable. Thereby they become cover terms that indicate linguistically quite different kinds of ambiguity.

However, as I have stated in the previous section, Their origin and nature touch upon a number of central issues that must be addressed by and theory of semantics. It is, by any means, the task of a linguistic description to make the differences between kinds of ambiguity more explicit. To achieve this goal, it is necessary first of all to maintain a basic distinction between the content of a sentence and its interpretation. By the content of a sentence I will understand: the inherent semantic structure of a sentence as a type, such as it is specified in a linguistic description.

By the interpretation of a sentence I will understand the various ways in which one and the same sentence can be understood in each unique case of language use, or, in Katz and Fodor's terms, the different 'readings of a sentence'. As a corollary to this distinction, I will distinguish between (i) the inherent meaning of a lexical element-its full specification in the lexicon, (ii) the possible further specification of its inherent meaning in the context of a particular sentence, (iii) the possible further specification in the interpretation of a sentence in language use.

Some lexical elements that can be understood in more than one way will accordingly be represented in the lexicon with distinct entries corresponding their various senses. But the mere fact that a lexical element can, on different occasions, be understood in more than one way, is not in itself a sufficient reason to represent it as having more than one distinct 'sense'. To cut the question short, I will henceforth use the term 'inherently polysemous' only to refer to lexical elements for which more than one entry is given in the lexicon.

There are three types of lexical ambiguity: polysemy, homonymy, and categorial ambiguity. Any practical natural language understanding system must be able to disambiguate words with multiple meanings, and the method used to do this must necessarily work with the methods of semantic interpretation and knowledge representation used in the system. Polysemous words are those whose several meanings are related to one another. e. g. Ambiguity describes the linguistic phenomenon whereby expressions are potentially understood in two or more ways; an ambiguous expression has more than one interpretation in its context.