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<Paper uid="W04-2206">
  <Title>A Method of Creating New Bilingual Valency Entries using Alternations</Title>
  <Section position="4" start_page="0" end_page="0" type="metho">
    <SectionTitle>
3 The Nature of the S=O Alternation
</SectionTitle>
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    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
3.1 Comparing Selectional Restrictions
</SectionTitle>
      <Paragraph position="0"> of A, O and S In alternations, a given semantic role typically appears in two di erent syntactic positions: for example, the dissolved role is the subject of intransitive dissolve and the object of the transitive. Baldwin et al. (1999) hypothesized that selectional restrictions (SRs) stay constant in the di erent syntactic positions. Dorr (1997), who generates both alternations from a single underlying representation, implicitly makes this assumption. In addition, Kilgarri (1993) speci cally makes the A h+sentient, +volitioni, while the O is h+changes-state, +causally affectedi.</Paragraph>
      <Paragraph position="1"> However, we know of no quantitative studies of the similarities of alternating verbs. Exploiting the machine translation lexicon for linguistic research, we compare the SRs of S with both A and O for verbs that take the S=O alternation.</Paragraph>
      <Paragraph position="2"> The SRs take the form of a list of semantic classes, strings or *. Strings only match speci c words, while * matches anything, even non-nouns. The semantic classes are from the GoiTaikei ontology of 2,710 categories (Ikehara et al., 1997). It is an unbalanced hierarchy with a maximum depth of 12. The top node (level 1) is noun. The lower the level, the more specialized LEX (Grishman et al., 1998). For example, the COMLEX 3.0 entry for gather notes that it coocurs with PPs headed by around, inside, with, in and into.</Paragraph>
      <Paragraph position="3"> the meaning, and thus the more restrictive the SR.</Paragraph>
      <Paragraph position="4"> We calculate the similarity between two SRs as the minimum distance (MD), measured as links in the ontology. If the SRs share at least one semantic class then the MD is zero. In this case, we further classi ed the SRs which are identical into \0 (Same)&amp;quot;. For example, in Figure 1, the MD between S and O is \0 (Same)&amp;quot; because they have the same SR: hstuffi. The MD between A and S is two because the shortest path from hartifacti to hstuffi traverses two links (artifact inanimate stuff).2 Figure 2 shows the MD between O and S, and A and S. The selectional restrictions are very similar for O and S. 30.1% have identical SRs, distance is zero for 27.5% and distance one is 28.3%. However, for A and S, the most common case is distance one (26.7%) and then distance two (21.5%). Although O and S are di erent syntactic roles, their SRs are very similar, re ecting the identity of the underlying semantic roles.</Paragraph>
    </Section>
    <Section position="2" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
Restrictions
</SectionTitle>
      <Paragraph position="0"> Next, we examine whether A, O, and S are h+sentient, +volitioni or not. In the GoiTaikei hierarchy, semantic classes subsumed by agent are h+sentient, +volitioni. A was very agentitive, with 60.1% of the SRs being subsumed by agent. The most frequent SR for A is hagenti itself (41.4%). S and O are less agentitive, with 13.9% and 14.1% of their respective selectional restrictions being agentitive. This data supports the hypothesis in Kilgarri (1993).</Paragraph>
      <Paragraph position="1"> 2There is some variation due to lexicographer's inconsistencies. For example X's SR is hstuffi in the intransitive and hinanimatei in the transitive entry. It should be hstuffi in both entries.</Paragraph>
      <Paragraph position="2"> In summary, the SRs of S and O are not identical, but very similar. In comparison, A is more agentitive, and not closely linked to either.</Paragraph>
    </Section>
    <Section position="3" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
3.2 Comparison of Japanese and English
</SectionTitle>
      <Paragraph position="0"> From the point of view of constructing bilingual lexical entries, if the English main verb can translate both Japanese entries, then it is possible to automatically construct a usable English translation equivalent along with the Japanese alternation. In order to see how often this is the case, we compare Japanese and English alternations and investigate the English translations in the alternation list.</Paragraph>
      <Paragraph position="1"> We divide the entries into ve types in Table 2. The rst three are those where the main English verb is the same. The most common type (30.0%) is made up of English unaccusative verbs which also undergo the S=O alternation [S=O]. The next most common (19.8%) is entries where the Japanese intransitive verb can be translated by making the transitive verb's English translation passive [passive]. In the third type (6.5%) the English is made transitive synthetically [synthetic]: a control verb (normally make) takes an intransitive verb or adjective as complement. The last two are those where either di erent translations are used (42.8%), or the same English verb is used but the valency change is not one of those described above.</Paragraph>
      <Paragraph position="2"> The rst three rows of Table 2 show the verbs whose alternate can be created automatically, 56.3% of the total. This gure is only an approximation, for two reasons. The rst is that the translation may not be the best one, most verbs can have multiple translations, and we are only creating one. The second is that this upper limit is almost certainly too low. For many of the alternations, although our table contained di erent verbs, translations using identical verbs are also acceptable. In fact, most transitive verbs can be made passive, and most intransitive verbs embedded in a causative construction, so this alternative is always possible (and is also possible for Japanese). However, if the Japanese uses a lexical alternation, it is more faithful to link it to an English lexical alternation when possible.</Paragraph>
    </Section>
  </Section>
  <Section position="5" start_page="0" end_page="0" type="metho">
    <SectionTitle>
4 Method of Creating Valency Entries
</SectionTitle>
    <Paragraph position="0"> In this section we describe how we create new alternating entries. Given a verb, with dependents Ni, and an alternation that maps some or all of the Ni, we can create the alternate by analogy with existing alternating verbs. The basic ow of  creating valency entries is as follows.</Paragraph>
    <Paragraph position="1"> For each dependent Ni if Ni participates in the alternation if Ni has an alternate in the target then map to it else delete Ni else transfer [non-alternating dependent] If the alternation requires a dependent not in the source Add the default argument We use the most frequent argument in existing valency entries as a default. Speci c examples of creating S = O alternations are given in the next section.</Paragraph>
    <Paragraph position="2"> Although we only discuss the selectional restrictions and subcat information here, we also map the verb classes (given as verbal semantic attributes (Nakaiwa and Ikehara, 1997)). The mapping for the dependents in the alternation can be taken from existing lexical resources (Dorr, 1997), learned from corpora (McCarthy, 2000) or learned from existing lexicons (Bond et al., 2002).</Paragraph>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
4.1 Target
</SectionTitle>
      <Paragraph position="0"> In this experiment, we look at one family of alternations, the S = O alternation. The candidate words are thus intransitive verbs with no transitive alternate, or transitive entries with no intransitive alternate. Alternations should be between senses, but the alternation list is only of words. Many of the candidate words (those that have a entry for only one alternate) have several entries. Only some of these are suitable as seeds. We don't use entries which are intransitive lemmas but have an accusative argument, which are intransitive (or transitive) lemmas but have an transitive translation (or intransitive), or which have both topic and nominative, such as (1), where the nominative argument is incorporated in the English translation.</Paragraph>
      <Paragraph position="2"> There are 115 entries (37 lemmas) which have only intransitive entries and 81 entries (25 lemmas) which have only transitive entries which are in our reference list of alternating verbs. We create intransitive entries using the existing transitive entries, and transitive entries using the existing intransitive entries.</Paragraph>
    </Section>
    <Section position="2" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
4.2 Creating the Japanese subcat and
</SectionTitle>
      <Paragraph position="0"> SRs In creating the intransitive entries from the transitive entries, we map the O's SRs onto the S's SRs, and change the case marker from accusative to nominative. We delete the A argument, and transfer any other dependents as they are.</Paragraph>
      <Paragraph position="1"> In creating the transitive entries, we map the intransitive S's SRs onto the new O's SRs, and give it an accusative case-marker. If the intransitive entry has a demoted subject argument (where the Japanese case-marker is ni and the English preposition is by), we promote it to sub-ject and use its SR for A. Otherwise we add a causative argument as ergative subject (A) with a default SR of hagenti3 and a nominative casemarker. We show an example in Figure 3.</Paragraph>
    </Section>
    <Section position="3" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
4.3 Creating the English Equivalents
</SectionTitle>
      <Paragraph position="0"> The English translation can be divided into three types: S=O, passive and synthetic.</Paragraph>
      <Paragraph position="1"> Therefore it is necessary to judge which type is appropriate for each entry, and then create the English. This judgement is shown in Figure 4. To judge whether an English</Paragraph>
    </Section>
  </Section>
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