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<Paper uid="W97-0503">
  <Title>Simple NLP Techniques for Expanding Telegraphic Sentences</Title>
  <Section position="2" start_page="0" end_page="18" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Some people have disabilities which make it difficult for them to speak in an understandable fashion. The field of Augmentative and Alternative Communication (AAC) is concerned with developing methods to augment the communicative ability of such people. In addition to problems that make &amp;quot;speaking&amp;quot; difficult, AAC users often have difficulties in coordinating extremities (so typing on a standard keyboard may be impossible and access to large keys is often very slow). Cognitive difficulties may also be present. The field of AAC is concerned with developing methods that provide access to communicative material under reasonable time and cognitive constraints. null Over the past 9 years, the Applied Science and Engineering Laboratories (ASEL) at the University of Delaware and the duPont Hospital for Children, has been involved with applying natural language processing (NLP) technologies to the field of AAC. One of the major projects at ASEL (The COMPANSION project) has been concerned with the application of primarily lexical semantics and sentence generation technology to expand telegraphic input into full sentences (McCoy et al., 1989), (Demasco and McCoy, 1992), (McCoy et al., 1994).</Paragraph>
    <Paragraph position="1"> The project can best be thought of as a rate enhancement technique used in the context of a writing tool. Assuming the user is selecting full words at a time (so time of word selection is basically constant and is independent of the number of letters iri the word), the technique shows the most gain when used by a linguistically sophisticated user who desires well-formed English constructions. The system speeds rate by allowing the user to select basic content and having the system provide expansions into well-formed sentences. The user may then select among the generated expansions with 1 additional keystroke (for example).</Paragraph>
    <Paragraph position="2"> Consider the following input: Mary think 3 watch give John Andrew.</Paragraph>
    <Paragraph position="3"> expanded as: Mary thinks that the 3 watches were given to John by Andrew.</Paragraph>
    <Paragraph position="4">  Notice that assuming a root word can be selected in a single keystroke and endings added with additional keystrokes, the initial input would take 7 keystrokes, while the expanded version would have required 16.</Paragraph>
    <Paragraph position="5"> The Compansion prototype contains three processing modules and requires a great deal of lexical knowledge: Word Order Parser - encodes a loose grammar of telegraphic sentences and determines and attaches modifiers (e.g., 3 is an adjective which is modifying watch), determines part of speech information (e.g., think is a verb, watch is a noun), and passes sentence sized chunks to the next phase of processing (e.g., first 3 watch give John Andrew would be passed on to the next phase, and then Mary thinks with the result of the previous processing).</Paragraph>
    <Paragraph position="6"> Semantic Parser - uses semantic information associated with words to create a semantic representation (Fillmore, 1968), (Fillmore, 1977), (Allen, 1995), (Palmer, 1984), (Hirst, 1987) for each sentence. E.g., verb frame information is associated with each verb. This information indicates which cases the verb is likely to have and the semantic type of words that are likely to fill those cases. Individual nouns have associated semantic types.</Paragraph>
    <Paragraph position="7"> Sentence Generator - creates an actual English sentence from the semantic representation (E1hadad, 1991). In this phase the system attempts to keep the word order that was originally input.</Paragraph>
    <Paragraph position="8"> While the Compansion prototype is viewed as a promising and successful application of NLP to AAC, it raises some questions when viewed as a practical AAC system.</Paragraph>
    <Paragraph position="9"> * Unlimited Vocabulary - Compansion relies on having a large amount of semantic information associated with each word for the processing within the semantic parser. We have been investigating gathering as much of this information as possible through online lexical resources (Zickus, 1995), (Zickus et al., 1995), but much of this information must still be hand encoded.</Paragraph>
    <Paragraph position="10"> This is particularly true of verbs which are the cornerstone of the semantic reasoning. While some information on noun semantic categorization can be gleaned from online lexical resources such as WordNet (Miller, 1990; Miller, 1995), it is well beyond the state of the art to glean the kind of verb semantics necessary from online resources. null Sophisticated Grammatical Input - Sophisticated writers are apt to want to use complicated grammatical constructions which may lie outside the processing ability supplied by the Compansion technique. In some instances the fault may be that the system has not yet been programmed to deal with certain constructions (e.g., certain kinds of verb compliments). Such deficiencies can be remedied. Much more serious is the possibility of some grammatical constructions not being understandable in telegraphic form even to a human reader. For example, relative clauses in telegraphic input may be impossible for a human to interpret correctly (at least, unless a great deal of world knowledge information is applied). Thus, there is a limit to the sophistication of grammatical constructions that are possible to disambiguate in telegraphic input.</Paragraph>
    <Paragraph position="11"> Sophisticated Grammatical Output - The sentence generator used by Compansion relies on a grammar which necessarily encodes some limited set of grammatical constructions.</Paragraph>
    <Paragraph position="12"> These problems, coupled with the relatively low processing power and space on devices used for AAC, led us to question whether or not NLP is possible in viable AAC devices. Notice that the rate enhancement power of Compansion is heightened when sophisticated linguistic constructions are used. On the other hand, it is exactly the situations where such constructions are most used that the other problem areas of the system are most prevalent.</Paragraph>
    <Paragraph position="13"> The question is: Are there uses for techniques such as Compansion that avoid some of the above mentioned problems? Is it feasible and beneficial to provide some kind of &amp;quot;pared-down&amp;quot; version of Compansion on an AAC device? In conjunction with the Prentke Romich Company (PRC) (a well known communication device manufacturer) we have been working on developing a pared-down version of Compansion for people with cognitive impairments (McCoy et al., 1997). In the next section we motivate the focus on this population. We indicate that not only might the technique prove very useful for this population, but by focusing on this population some of the problems with Compansion can be eliminated. We describe our processing (a simplification of the processing in Compansion) and note some challenges that still remain. null</Paragraph>
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