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<Paper uid="P84-1024">
  <Title>Semantic Interpretation Using KL-ONE 1</Title>
  <Section position="3" start_page="0" end_page="102" type="intro">
    <SectionTitle>
2. Background
</SectionTitle>
    <Paragraph position="0"> The framework being developed uses a frame for each semantically distinguishable type of phrase. Thus, a frame will be required for each class of phrase having a uniq.ue combination of . semantic distribution, - selection restrictions on constituents making up the phrase, and -_assignment of semantic relations to syntactic function.</Paragraph>
    <Paragraph position="1"> It is likely that the frames will reflect the natural categories of descriptions of objects, events, actions, and states of affairs in any particular application. For example, in the computer mail domain, the following are some frames that have been useful:  - Clauses describing the sending of messages: SEND. CLAUSE - Clauses describing message arrival: ARRIVE.</Paragraph>
    <Paragraph position="2"> CLAUSE - Noun phrases describing messages: MESSAGE-NP  -Noun phrases describing senders and recipients: USER-NP In the framework developed by Bobrow and Webber \[Bobrow&amp;Webber 80a, Bobrow&amp;Webber 80b\], for each frame, each possible immediate constituent is associated by syntactic function with a case or slot. The clause frames have slots identified as head, subject, 4&amp;quot;direct object, indirect object, etc. Noun phrase frames have slots for the head, adjective modifiers, article, etc. Each slot specifies the fillers that are semantically acceptable, whether it is required or optional, and the number of times it may be filled in a phrase. The constraints on fillers of frames' slots are stated in terms of other frames, e.g., the direct object of a SEND-CLAUSE must be a MESSAGE.NP, or in terms of word senses and categories of these senses. Some example word sense categories are:  * Message description nouns, such as &amp;quot;message&amp;quot; or &amp;quot;letter&amp;quot;: MESSAGE.NOUN * Information transmission verbs, such as &amp;quot;send&amp;quot; or &amp;quot;forward&amp;quot;: TRANSMISSION.VERB  In our domain the constraint on the subject of an ARRIVE-CLAUSE is that it satisfies the MESSAGE.NP frame. A constraint on the head of the MESSAGE.NP frame is that it is a word sense in the category MESSAGE.NOUN.</Paragraph>
    <Paragraph position="3"> Frames are represented as KL.ONE concepts. Case slots appear as roles of concepts. 5 Semantic constraints on what can fill a case slot are encoded as the value restrictions of roles. These value restrictions are concepts representing frames, word senses, or word sense categories. Number restrictions on roles show the number of times the syntactic function may be realized. A required slot is marked by the number restriction on its role having a minimum of 1; an optional slot has a number restriction with a minimum of 0 and a maximum greater than 0. A phrase is said to instantiate a given frame X if and only if its immediate constituents satisfy the appropriate value and number restrictions of all of X's roles. 6 The collection of frames and word-sense 4Subject, object, etc. refer to logical roles rather than surface syntactic ones. 51t is possible to associate roles with semantically defined subsets of other roles, e.g., to assign separate roles to uses of color adjectives, size adjectives, etc. This is an important convenience in constructing frames but not crucial to our discussion.</Paragraph>
    <Paragraph position="4"> 6A recognition algorithm for this representation has been presented \[Bobrow&amp;Webber 80b\] and several others have been developed since then. Thase will be presented in separate reports.</Paragraph>
    <Paragraph position="5">  information is called a Syntaxonomy (for syntactic taxonomy), since it encodes knowledge regarding semantic interpretation in a hierarchy of syntactic classes.</Paragraph>
  </Section>
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