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<?xml version="1.0" standalone="yes"?> <Paper uid="C82-1011"> <Title>FRAME BASED RECOGNITION OF THEME CONTINUITY</Title> <Section position="3" start_page="71" end_page="71" type="metho"> <SectionTitle> 72 J.T. CRITZ </SectionTitle> <Paragraph position="0"> frame which can be reasonably associated with it in the given context and links the frame with those extablished in the preceding text. The objects which are the primary referents of a sentential theme are assigned the role of being major nodes through which one frame is linked directly or, where more abstract associations can be inferred, indirectly with others relevant to the continuity of the text. The concept of &quot;frame&quot; is that described in M. Minsky (1977).</Paragraph> <Paragraph position="1"> In the following sections the concepts of &quot;theme&quot; and &quot;frame&quot; are defined more explicitly and the manner in which the system relates them to each other is described. While the system is designed to operate on English text, comparisons will be made to Czech.</Paragraph> </Section> <Section position="4" start_page="71" end_page="71" type="metho"> <SectionTitle> THEMES </SectionTitle> <Paragraph position="0"> Within the grammatical theory of the Prague School of Linguistics a sentence is composed of a minimum of two major constituents - a &quot;theme&quot; (&quot;topic&quot;) and a &quot;rheme&quot; (&quot;comment&quot;). (A sentence may also contain components which function as a transition between these two, but such components will not be discussed here.) The theme - rheme division of a sentence typically conforms, in non-contrastive environments, to the NP subject and VP major constituents of a sentence, with the theme being the first of these to appear in the surface word order of the sentence. Because of its more restrictive word order, the theme of a sentence in English is normally its subject. In Czech, however, a sentential subject may more easily appear in the latter part of a sentence.</Paragraph> <Paragraph position="1"> In its attempt to associate the theme of a sentence with a frame, our system reduces the object of its operation to a &quot;theme object&quot;, defining this for English as the referent of the highest noun within the theme constituent: normally, the subject head noun. Within VPs functioning in English sentences as theme the theme object would be the direct object's head noun, or, given other contrastive stress, the head noun of the phrase containing the highest peak of intonation were the sentence spoken.</Paragraph> <Paragraph position="2"> It is important to note that the theoretical basis for labelling a sentence constituent as theme does not necessarily mean that the theme object has been previously mentioned in the text. The immediate introduction of new theme objects in English is obvious from the existence of non-definite themes in examples like (3).</Paragraph> <Paragraph position="3"> (3) The old hotel burned down last year. A new restaurant is to take its place.</Paragraph> <Paragraph position="4"> However, unless some relation can be found between contextually new themes and the existing context, sentences with non-definite themes would be either make a text discontinuous or would maintain their continuity only indirectly through the relation of the theme to another noun in the same sentence which is anaphoric. In either case there would be little justification for assigning a thematic function to non-definite nouns, and the general definition of theme proposed by the Prague School would have to be greatly altered or dropped.</Paragraph> </Section> <Section position="5" start_page="71" end_page="71" type="metho"> <SectionTitle> FRAME BASED RECOGNITION OF THEME CONTINUITY 73 </SectionTitle> <Paragraph position="0"> The association of themes with frames provides continuity without the requirement for explicit previous mention. The claim made in associating themes and frames is that themes are not referentially simple: their meaning involves reference not only to some individual, act, event, etc., but also reference to some structured set of these with which the noun referent is associated. Continuity lies in the existence of an assumed shared relation holding between a theme and other objects previously mentioned.</Paragraph> </Section> <Section position="6" start_page="71" end_page="71" type="metho"> <SectionTitle> FRAMES </SectionTitle> <Paragraph position="0"> A frame may be generally defined as a limited complex of objects, acts, events, and/or states, whose association is determined by convention or experience and is assumed and expected by a speaker or author to be known by his or her ~udience. Simple frames include: the association of the objects &quot;the bathroom&quot; (&quot;koupelna&quot;), &quot;the bedrooms&quot; (&quot;lo~nice&quot;), &quot;the kitchen&quot; (&quot;kuchyn~&quot;), &quot;the roof&quot; (&quot;st{echa&quot;), etc., with the frame &quot;h)use&quot;, or the sequence &quot;the morning&quot; (&quot;r~no&quot; a &quot;dopoledne&quot;), &quot;noon&quot; (&quot;poledne&quot;), etc., as parts of the frame &quot;day&quot;. Reference to one member of a frame suffices to make other members of the frame available as possible themes. For example, mention of &quot;the kitchen and bathroom&quot; implies the frame &quot;house&quot;, and this mention, if themes are assumed to be bound to frames, suffices to allow the occurrence of &quot;the house&quot;, &quot;the garden&quot; or other associated object as a theme in a later sentence.</Paragraph> <Paragraph position="1"> The primary characteristics of a frame, as defined in our natural language system, and distinguishing frames from other relational structures, are that each member of the frame must be uniquely identifiable (This uniqueness also specifies the member's role in the frame.) and that the members share a common relation or property which uniquely characterizes the frame to which they belong. Recognition that a given object is a unique member of a frame is the attribution of the property of &quot;definiteness&quot; to that object. A non-definite theme is interpreted as a description of a frame object, but the reference itself as definite.</Paragraph> </Section> <Section position="7" start_page="71" end_page="71" type="metho"> <SectionTitle> DETERMINING CONTINUITY </SectionTitle> <Paragraph position="0"> Themes and frames are related to each other through the following process. The main components of the system include: - a parser - a lexicon, providing not only the possible syntactic and semantic representations of each lexical item and conditions on their use, but also an index to the frames normally associated with the entry - a frame dictionary, stating the set types of the possible members for each frame and their relationship to each other within the frame - a set of logical inference and interpretive rules, which can be used to relate frames in the construction of a frame system representing changes in the continuity and development of a text - a list of frames currently activated by theme reference, interpretation or inference</Paragraph> </Section> <Section position="8" start_page="71" end_page="71" type="metho"> <SectionTitle> 74 \]J.T. CRITZ </SectionTitle> <Paragraph position="0"> During the parse of a sentence the head noun of the sentence is selected as the most likely candidate for being its theme and, provided that tests of the sentence and the onepreceding it do not indicate a contrastive environment requiring the selection of another noun as theme, declares it to be the theme. The frames indexed in the lexical entry for the theme noun are then searched and compared for identity with or inclusion within those frames currently active. Those frames most recently used and those which a~e associated with anaphoric noun phrases within the sentence are examined first. If the sentence being processed is the first sentence in the text or if a search of all active frames fails, the theme is associated with a &quot;base&quot; frame. The base frame for a text includes as its members the set types {AUTHOR}, {AUTHOR'S GOAL~, READER and other nodes which may be filled by objects or persons these as part of their immediate world.</Paragraph> <Paragraph position="1"> The frame system for the text is built of the relationships holding between all the activated frames and the base frame.</Paragraph> <Paragraph position="2"> The process is illustrated for (4). For reasons of space, the hierarchical relations which hold between members of each frame is not shown. An AGENT frame is automatically assigned to persons mentioned in a text. The LOCATION, BUILDING and LOCK frames in (4) are interpreted.</Paragraph> <Paragraph position="3"> (4) John turned the key. The door still would not move.</Paragraph> <Paragraph position="4"> BASE {... \[John\] \[author\] \[reader\] ...~ AGENT (... \[John\] \[LOCATION > BUILDING\] \[GOAL\] BUILDING {... \[door\] ..-7 LOCK (... \[key\] \[bolt\] ...~ DOOR (... \[lock\] \[handle\] ...) }</Paragraph> </Section> <Section position="9" start_page="71" end_page="71" type="metho"> <SectionTitle> COMPARING ENGLISH AND CZECH TEXTS </SectionTitle> <Paragraph position="0"> Comparing the processing of English and Czech texts, it is important to note that while most frames can be expected to be the same for both languages, frame membership and relations between frame members which are dependent on cultural, political, linguistic and similar differences will cause frames to differ at least at the lower node levels. The &quot;day&quot; frame menti6ned earlier, in which English &quot;morning&quot; is paralleled by &quot;r~no&quot; and &quot;dopoledne&quot; in Czech, is one example.</Paragraph> <Paragraph position="1"> An even more significant difference is found in the effect of varying restrictions on word order in the two languages. Czech seems to indicate shifts to new frames by moving subject nouns which would b e thematic in the English equivalent of the sentence to the end of the sentence. Where the same frame or same samll set of frames can be associated with consequetive subjects in the text, the subject is thematic. An example of this can be seen in (5), where &quot;cesta&quot; (&quot;trip&quot;) is associated with the general frame of a person's daily life and with Karel's in particular. In (6),</Paragraph> </Section> class="xml-element"></Paper>