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<Paper uid="P90-1004">
  <Title>Empirical Study of Predictive Powers of Simple Attachment Schemes for Post-modifier Prepositional Phrases</Title>
  <Section position="13" start_page="27" end_page="29" type="concl">
    <SectionTitle>
OTHER PP MODIFIERS
</SectionTitle>
    <Paragraph position="0"> The remaining PP modifiers, those that are probably not sought after by an LP verb or noun and do not belong to the class of temporal-PPs or locative-PPs, were treated together. The reason for this particular grouping was that there were a number of functions evident in some PPs that occurred very infrequently and since one of the major foci of the study was to try to find general means of deciding attachment of PPs, individualization of these PPs was, at first, discounted. In some of the prior attachment schemes, there were some elements that were given the power to seek out some other constituent (e.g. LP verb sought out certain case types presented in particular PPs and temporal PPs sought out temporal-bearing nouns or verbs). Attempting to use LP with the varied other group was not possible since no one function type (e.g. such as temporality) and no single preference characteristic was evident. Other schemes were necessary for this group.</Paragraph>
    <Paragraph position="1"> What proved to be succesful was the Hirst (1987) modified version of presupposition in which attachment to definites is generally avoided. Adding the notion of RA, one can also decide between equally weighted non-definites and verbs when both are present.</Paragraph>
    <Paragraph position="2"> The combined presupposition-RA algorithm is expressed below. When coming upon a PP that was of the other type, an attachment is made to the most recent verb or non-definite noun in a RA fashion.</Paragraph>
    <Paragraph position="3"> Avoid attachment to definite NPs and attach to most recently occurring verb or non-definite NP to the left.</Paragraph>
    <Paragraph position="4"> As shown below under this scheme, correct prediction was made 100% of the time for the nondefinite+verb grouping. However, when examining the success of attachment with the definite NPs, the rate of successful prediction was much lower.</Paragraph>
    <Paragraph position="5"> In 13 instances, avoiding attachment to definite NPs was the correct thing to do, but 7 times it was not, resulting in a 65% success rate. Thus if one permits the RA+non-definite noun preferencing scheme, the only items needing further explanation are the definite NPs.</Paragraph>
    <Paragraph position="6"> of correct predictions of attaching &amp;quot;other&amp;quot; PPs to last occurring available verb or non-definite noun to the left I00~ of correct prediction to avoid attachment to definite NPs. 65X With the limited group of 7 definite NPs (these were the remaining, unresolved definite NPs), it was easy to identify a single class to which the conflicting NPs belonged. All the nouns but one 5 that could be associated with PPs were ones that could be used in partitive expressions. Partitive nouns can be separated out from other nouns as those noun expressions that denote a kind or quantity and are typically followed by the preposition of. In  (6) are two examples from the dialogues.</Paragraph>
    <Paragraph position="7"> (6) a. the legs of your trip.</Paragraph>
    <Paragraph position="8"> b. the size of the hotel  The algorithm for the other group is: Check to see if preceding lowest constituent is a definite NP and part of a partitive expression, If it is, attach the PP to the preceding definite NP, Otherwise, attach to the most recently occurring verb or non-definite NP.</Paragraph>
    <Paragraph position="9"> 5The sole exception was with the noun \]eeling in the expression the \]eeling o\] the community. It is highly probable that this is an idiomatic noun phrase and should be entered in an idiomatic lexicon.</Paragraph>
    <Paragraph position="10">  Overall Algorithm As laid out below after some preliminary tasks are performed, namely associating nouns with their adjectives and extracted items with their gaps, the first preference to apply is noun and verb LP. If noun and verb LP fails, the two-stepped temporal/locative modifer preference can step in and perform attachments of which it is capable. When all else fails, the other modifier routine finishes off anything left over.</Paragraph>
    <Paragraph position="11"> Associate adjectives with locative (and possibly temporal) qualities to the nouns they modify.</Paragraph>
    <Paragraph position="12"> Associate extracted items with their respective 'gaps.' If an LP verb or LP noun is present, apply verb or noun LP.</Paragraph>
    <Paragraph position="13"> If two LP verbs or nouns are present that seek the same PP, use the notion of RA and attach the PP to the last word that seeks it.</Paragraph>
    <Paragraph position="14"> Otherwise, if a temporal PP is present, attach it to the most adjacent constituent to the left whose head contains a temporal quality.</Paragraph>
    <Paragraph position="15"> Otherwise, if a locative PP is present, attach it to the most adjacent constituent to the left whose head contains a locative quality.</Paragraph>
    <Paragraph position="16"> Otherwise, if an OTHER modifier (not a temporal or a locative) is present and if the immediately preceding element is a definite NP that could be part of a partitive expression, then attach the PP to the NP, Otherwise attach to the last occurring verb or non-definite NP.</Paragraph>
    <Paragraph position="17"> Conclusion The study indicates that there seems to be a way of predicting PP attachment in the typed interactive mode of communication by fairly simple means. By using LP for nouns, verbs and prepositions (temporal and locative PPs seek out temporal- or locative-accepting elements) and a variation on the Crain and Steedman notion of presupposition, attachments are essentially always predictable.</Paragraph>
    <Paragraph position="18"> Correct interpretation of the 724 instances it~ which there existed structural ambiguity in the attachment of PPs to nouns or verbs occurred as follows: null  :added note - two items were not accounted for: --- one seemed to be an idiomatic expression --- one may possibly have been contextually related RA played a role within each preferencing scheme as did a weak notion of plausibility. RA was used as the arbitrator whenever there remained an intraconflict in a preferencing algorithm (and sometimes when there was inter-conflict between schemes). The use of plausibility to talk about relationships between verbs or nouns and associated PPs was thought to be a necessary notion in that simple searches for only prepositions were deemed to be too weak of a notion. When verb or noun LP was at work, nouns and verbs sought out PPs (as opposed to single prepositions) that as a whole had some attribute(s) necessary to fulfill some semantic requirements. Sometimes PPs also had to be concluded to be of a particular type in order to search out a unique kind of noun or verb. Apparently, PP Lexical Preferencing allowed PPs that were temporal or locative in nature to look for nouns and verbs that bore temporal or locative characteristics, respectively. Referential Success in its pure sense was a poor predictor of attachments. However, the related notions of presupposition regarding definites, indefinites, etc. were good predictors of attachment for a small number of PPs.</Paragraph>
    <Paragraph position="19"> Finally, a more cognitive finding resulting from the study was the great predictability of attachment, suggesting that there is something about the typed interactive mode of communication that coilstrains the possibilities on attachment such that attachment always goes with the unmarked ce, sc. There are at least three pressures that may help to make these constraints come about. One is the  lack of the spoken element which carries with it intonation patterns and variations in pausing that can influence the ways that one parses. One must rely on only the cues available by written means to aid in disambiguating attachments. Secondly, the added comparative slowness at which interlocutors type and the resulting tendency to leave out unnecessary punctuation marks often useful in disambiguating text makes yet a further constrained subset. Thirdly, a speaker may be aware of the time lag (hence taxation on memory) that exists between typing some modified element and its associated PP. The lag may have an effect on how such pairs are presented. Prominent ways of highlighting the links may depend more on notions such as LP or RA that might not be needed as much in other modes of communication. These factors together may make it necessary for participants in typed interactive communication to rely on a set of default structures that each can cue on easily. A cknowledgements We wish to thank Joyce Conner for her time and energy spent in collecting and analyzing the data, Melissa Macpherson for her insights into the notions presented in the paper, and Laurie Whittemore and Jim Barnett for their editing efforts. Also, much of the work on this paper was carried out when Greg Whittemore and Kathy Ferrara were employees of MCC, and thanks goes to MCC personnel, particularly Elaine Rich, who made it possible for the study to be performed.</Paragraph>
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