Parsing words and sentences ambiguous between opposite meanings using INTEX finite state grammars: You can’t take ambiguity too seriously

paper
Authorship
  1. 1. Ray C. Dougherty

    Dept of Linguistics - New York University

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Ambiguity poses a serious challenge to any computational system that attempts to extract a meaning or sense from an input sentence. Some ambiguities can be clarified by reference to the surrounding text. G. Miller has pointed out that the word line is at least six ways ambiguous considered only as a noun. The word right is ambiguous in meaning and can be at least four different parts of speech (noun, adj, adverb, verb) according to WordNet.

For a parser that analyzes a sentence one word at a time from left to right an ambiguous word can sometimes lead to ‘garden path’ phenomena, widely discussed in sentence processing literature, and most recently in Fodor and Inoue (eds.) A sentence like The horse raced past the barn died may ‘fool’ a parser into marking raced as the past of the verb race and assigning the string The horse raced past the barn a sentence structure. When the word died is encountered, this indicates that the analysis of the earlier string must be changed to yield a relative clause: The horse (that was) raced past the barn died. A garden path sentence contains (a) an ambiguous element that can be assigned two structures or meanings when the parser encounters it and (b) must be assigned only one of those meanings when the parser encounters a later element in the sentence, called the ‘disambiguator’.

My study focuses on garden path sentences that are ambiguous between opposite readings. In all cases, the ambiguous element is a verb (put, wash) such that a later element (a particle: out) changes the sentence to an opposite reading. I will discuss Quine’s ideas about the semantic analysis of sentences like You cannot take the newspapers too seriously, which can mean take them more seriously or pay them little heed. These ambiguities in a computerized natural language interface to a database are particularly pernicious. A simple ambiguity (line: telephone line, a new line of clothes, a line in the sand, she gave him a line, I have a line on it) may return information about Gucci’s latest line rather than AT&T’s lines. But an intelligent reader can sift the wheat from the chaff. The particle out is like the element not. It reverses the sense of the sentence, but the sentence is usually well-formed with or without the out.

I discuss the INTEX lexical entries required to deal with cases of ‘ambiguous’ semantic readings in ‘verb’ versus ‘verb particle’ constructions that occur with examples like pan and pan out. My theory of cognition panned out. This implies that my theory had some success and is a positive statement. The critic panned my theory of cognition. This implies that my theory had a setback and is a negative statement. For some, The play panned in London, means that it failed, while The play panned out in London means that it was successful. I present the INTEX finite state analysis for examples involving …pan… which would have a ‘negative’ interpretation until an …out… is encountered, whereupon …pan…out… would be given a ‘positive’ interpretation.

If pan is negative and pan out is positive, then out has the opposite effect with wash. The noun washout usually means ‘failed’ as in: Our complicated financial pans were a washout. But wash can mean ‘succeed’ or ‘come out even’ as in: Our complicated financial plans were a wash. As a verb, wash is ‘positive’ implying success, as in: Your financial plans will wash. Wash out is ‘negative’ implying failure, as in: Your financial plans will wash out. A left-right parser assigning semantic interpretations must ‘change’ its semantic interpretation for pan and wash. It worked and it worked out are both positive implying success. It flunked (out) and it punked (out) are all negative suggesting failure. I present the INTEX English grammar and lexicon of common examples found in English newspapers and machine readable journals by GlossaNet.

I am using INTEX to examine the occurrences of pan, pan out, wash, washout, and wash out in the New York Times, Wall Street Journal, and several other papers to study the possible ambiguities and specific interpretations in actual samples. Since there is a federal tax law popularly known as the ‘wash law,’ there are many examples with wash and wash out both in professional journals and in newspapers. INTEX has parsed the past two years of these newspapers. Research having native and non-native English speakers semantically tag texts suggests that non-native speakers of English – who are unaware of the meaning reversal in these verbs – misunderstand passages in leading newspapers. One must speak excellent native English to understand financial and political discussions in newspapers. Non-native speakers sometimes think a financial failure (pan, washout, wash out) is a success (pan out, wash). If this research pans out, it will wash, but if it pans, it will wash out and be panned as a washout.

Words that are ambiguous between opposite readings can cause havoc in two situations I discuss. Search engines may return cases that are the opposite of what you want with no indication that they are the opposite, for instance it may list projects that collapsed (panned, washed out) when you want projects that succeeded (panned out, washed). And, if the out is carelessly handled in translation machines, the machine may take an input sentence that claims some project succeeded and translate it to indicate that the project failed. My grammar and lexicon are INTEX finite state graphs. All my example sentences were located in machine readable text by GlossaNet.

References

Gross, Maurice. 1993. "Local grammars and their representation by finite automata", in Michael Hoey (ed.), Data, Description, Discourse, Papers on the English Language in honour of John McH Sinclair, Londres, Harper-Collins, p. 26-38.

Gross, Maurice. 1997. "The Construction of Local Grammars", in E.Roche et Y.Schabes (eds.), Finite State Language Processing, Cambridge, Mass., The MIT Press, p. 329-352.

Fodor, J. D. and Inoue, A. 1998. "Attach anyway". In Fodor, J. D. and Inoue, A. (Eds.), pp. 101-142

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Conference Info

In review

ACH/ALLC / ACH/ICCH / ALLC/EADH - 2001

Hosted at New York University

New York, NY, United States

July 13, 2001 - July 16, 2001

94 works by 167 authors indexed

Series: ACH/ICCH (21), ALLC/EADH (28), ACH/ALLC (13)

Organizers: ACH, ALLC