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<Paper uid="W96-0415">
  <Title>Denotation I t~not~tion I Denotation E co,n,\[ x Connotatiot~ Connotatior~ Colmolation I Partial / Partial \[ Partial C SemSpec SemSpec I SemSpec \[ 0 Alternation~ Altffnafio~ Alternations N MorphSyn |MorphSynt I MorphSynt Generation</Title>
  <Section position="8" start_page="145" end_page="149" type="concl">
    <SectionTitle>
4 Alternations and extensions
</SectionTitle>
    <Paragraph position="0"> Having explained denotations and PSemSpecs, specifically for verbs, we can now deal with the task of accounting for the different alternations a verb can undergo. A generator needs to know that a verb like to fill can occur in a variety of configurations: Water filled the tank, The tank filled with water, Tom filled the tank with water. The most, comprehensive source of information on verb alternations is the compilation by Levin \[1993\]; we inspect some of the more prominent, alternations listed there and characterize them in terms of changes in denotation and valency of the verbs.</Paragraph>
    <Section position="1" start_page="145" end_page="146" type="sub_section">
      <SectionTitle>
4.1 Alternations as meaning extensions
</SectionTitle>
      <Paragraph position="0"> A simple way of treating alternations is using a separate lexical entry for every configuration, but that would clearly miss the linguistic generalizations. Instead, we wish to represent the common &amp;quot;kernel&amp;quot; of the different configurations only once, and use a set of lexical rules to derive the alternation possibilities.</Paragraph>
      <Paragraph position="1"> Jackendoff \[1990\] is concerned with this problem for a number of alternations; specifically, in his LCS framework he seeks to explain the relationships between stative, inchoative, and causative readings of a verb (such as those of to fill given above). In Jackendoff's analysis, the forms are derived sequentially by embedding in the primitives INCH and CAUSE, respectively:  For our NLG purposes, the idea of deriving complex verb configurations from more basic ones is attractive, but it is necessary that we relate verb meaning to our explicit treatment of event structure, instead of masking that structure with a primitive like INCH. The idea is to see verb alternations not just as relations between different verb forms, but to add directionality to the concept of alternation and treat them as functions that map one into another. From this viewpoint, there are two groups of alternations: (1) Alternations that do not affect the denotation of the verb. Examples are the passive or the substance-source alternation (The tank leaked oil; Oil leaked from the tank): The truth conditions do not change. (2) Alternations that do change the denotation of the verb.</Paragraph>
      <Paragraph position="2"> The critical group is (2), because if we derive verb configurations from others and rewrite the denotation in this process, it has to be ensured that the process is monotonic. Therefore we define the directionality for group (2) to the effect that an alternation always adds meaning: the newly derived form communicates more than the old form--the denotation gets extended. This notion is different from the standard, non-directional way in which alternations are seen in linguistics; to label the difference, we call alternations of group (2) eztensions. In this section, we will introduce a number of extension rules for which we can give a clear definition in terms of Aktionsart features, as they were introduced in section 3.1. These rules extend the denotation of a verb and rewrite its PSemSpec in parallel to reflect the change in valency; the result is a new verbalization option, which can (lifter from the previous one in terms of coverage or attribution of salience (not discussed here). The rules will be conveniently simple to state, thanks to the upper model, which provides the right level of abstraction from syntax.</Paragraph>
      <Paragraph position="3"> We illustrate our goal with an example. If a SitSpec encodes the situation of Tom removing all the water  from a tank, then the verb to drain is a candidate lexeme. While it can appear in a number of different configurations, we wish to match only one of its forms against the SitSpec, though. This is the most basic one, denoting an ACTIVITY: The water drained from the tank. Here, the case frame of the verb has to encode that from the tank is an optional constituent.</Paragraph>
      <Paragraph position="4"> Now, an extension rule has to systematically derive the CAUSATIVE form: Tom drained the water from the tank. And also from the first configuration, another rule derives the RESULTATIVE reading, which adds the information that the tank ended up empty: The tank drained of the water. Here, of the water is an optional constituent. To this last form, a causative extension can apply and yield Tom drained the tank of the water.</Paragraph>
      <Paragraph position="5"> To compute these configurations automatically, we define an alternation or extension rule as a 5-tuple with the following components: NAM: a unique name; DXT: extension of denor.ation; C0V: additions to the covering-list; R0C: role changes in PSemSpec; NR0: additional PSemSpec roles and fillers.</Paragraph>
      <Paragraph position="6"> The DXT contains the denotation subgraph that the new verbalization has in addition to the old one. The syntax is, of course, the same as that of the denotation of a lexical entry. Specifically, it can contain variables; these can co-occur in the C0V list: the items that the new verbalization covers in addition to those of the old one. R0C is a list of pairs that exchange participant role names or the UM-type in the PSemSpec; this replacement can also change optionality.</Paragraph>
      <Paragraph position="7"> For example, (&lt; :actee &gt; :actor) means &amp;quot;replace the term : actee in the PSemSpec of the old verbalization, where it was optional, with : ac'eor, which is not optional.&amp;quot; Finally, Nl:t0 contains new roles and fillers that are to be added to the new PSemSpec; these will also contain variables from the denotation extension.</Paragraph>
      <Paragraph position="8"> Applying such a rule to a verbalization option vo works as follows: Add the contents of DXT to the denotation of vo, and match the new part against the SitSpec. If it matches, make a copy vo' of vo and assign it a new name as well as the denotation just formed. Add the C0V list, which has been instantiated by the matching, to the covering-list of vo'. Exchange the role names in the PSemSpec of vo' as prescribed by Ft0C, and, importantly, in the order they appear there. Finally, add NR0 to the PSemSpec.</Paragraph>
    </Section>
    <Section position="2" start_page="146" end_page="149" type="sub_section">
      <SectionTitle>
4.2 Lexical rules for extensions
</SectionTitle>
      <Paragraph position="0"> Stative-resultative Example: Water filled the tank / The tank filled with water. In discussing verbs that denote a STATE, Jackendoff \[1990\] points out that fill, cover, surround, and saturate can describe either a STATE or an inchoative event, and encodes the difference with the primitive INCH we have shown in the introduction to this section. Our goal is to do without the primitive, and to define the change in terms of the Aktionsart of the verb; to this end, we use RESULTA-WIVE in the place of 'inchoative' (see section 3.1). On a similar matter, Levin \[1993\] describes the 'locatum subject' alternation, which for instance holds between I filled the pail with water and Water filled the pail. It thus relates a causative and a non-causative form. Levin states that the alternation applies to a class of 'fill verbs', which are many more than the four given by Jackendoff, and her alternation is not exactly the one we need here, since it also involves a causative form--deriving this, however, is in our framework a separate step.</Paragraph>
      <Paragraph position="1"> What we need here is a mixture of Jackendoff's and Levin's insights: Several of Levin's fill verbs can be both transitive and intransitive; and some of the intransitive readings denote 'to become Xed'. Among these verbs are fill, flood, soak, encrust, or saturate: The kitchen flooded with water means the same as The kitchen be'came flooded with water. For this subgroup of the fill verbs we define an extension rule that, derives from a STATE reading a RESULTATIVE one. Notice that this is different from Levin's 'locatum subject' alternation, since it, does not, involve a causer.</Paragraph>
      <Paragraph position="2">  :actor B :acres A &lt; :destination C &gt;) When matching it against a SitSpec with a tank and water, this yields the verbalization The water filled the tank, covering only the POST-STATE of the Sit-Spec. Now, the alternation rule extends the denotation to also covering the EVENT and the ACTIVITY that brings the filling about. Applying the changes to the PSemSpec results in (x / nondirected-action :lax fill_el :inclusive B :actor A &lt; :destination C &gt;) from which PENMAN produces The tank was filled with the water.</Paragraph>
      <Paragraph position="3">  A few stative verbs cannot be RESULTATIVE without being also CAUSATIVE. Consider to cover in these examples from Jackendoff: Snow covered the ground.</Paragraph>
      <Paragraph position="4"> * The ground covered with snow.</Paragraph>
      <Paragraph position="5"> Bill covered the ground with snow.</Paragraph>
      <Paragraph position="6"> For these, a 'stative-culmination' extension derives the RESULTATIVE-\[-CAUSATIVE form directly from the STATIVE one. The rule is defined similar to the one given above, so we do not show it here.</Paragraph>
      <Paragraph position="7"> Causative extensions Example: The napkin soaked / Tom soaked the napkin. Levin discusses a 'causative/inchoative' alternation that, applies to a large number of verbs. The class formed by them is somewhat, heterogeneous with respect to the Aktionsart, though; it contains for example to move as well as to open. The former is in its basic form DURATIVE (The cat moved), and the latter TRANSFORMATIVE (The door opened). Accordingly, we split the alternation in two, which only differ in the DXT component, reflecting the difference in Aktionsart. The alternation adds a CAUSER to the denotation, makes the former : actor the new : actee, and accordingly changes the overall UM-type from NONDIRECTED-ACTION to DIRECTED-ACTION, because there is now an ACTEE present,.</Paragraph>
      <Paragraph position="8">  The first rule derives, for example, Tom moved the cat from The cat moved, and the second Tom closed the door from The door closed.</Paragraph>
      <Paragraph position="9"> Locative extensions Example: (a) Sally sprayed the wall with paint./(b) Sally sprayed paint onto the wall. We have mentioned the locative extension above; its characteristic is that configuration (a) of the verb conveys that something is performed in a 'complete' or 'holistic' manner, whereas configuration (b) lacks this facet of meaning. Levin points out that this alternation has received much attention in linguistics research and notes that, in spite of the efforts, a satisfactory definition of the 'holistic'-facet has not been found. Jackendoff, in his treatment of the alternation, suggests encoding the 'holistiC feature in a primitive: the Sally sprayed paint onto the wall.</Paragraph>
      <Paragraph position="10"> (spray. l (CAUSER sally-l) (OBJECT paint-l)  fimction ONa is a derivative of ON and means that something 'distributively' covers a surface, e.g., the paint covers all of the wall. Introducing a primitive, though, amounts to conceding that no explanation in terms that are already known can be given. We cannot solve the question of 'holisticness', either, but we want to point to the fact that the two verb configurations correlate with a change in Aktionsart: Sally sprayed paint onto the wall is durative (she can do it for two hours), whereas Sally sprayed the wall with paint is transformative (she can do it in two hours). That observation leads us to propose that the example is best analyzed as involving a mere ACTIVITY in the with configuration, and an additional TRANSITION in the onto configuration. Hence, we assign two different SitSpecs for the sentences, one ACTIVITY and one EVENT, as shown in figure 3.</Paragraph>
      <Paragraph position="11"> The crucial point now is that the first SitSpec is fully embedded in the second; this is in correspondence with the truth conditions: If Sally has sprayed the wall with paint, then she also has sprayed paint onto the wall. To generalize the correspondence to an extension rule, we need to assume in the domain model a concept like COMPLETION-STATE, which is to subsume all those STATES in the domain model that have &amp;quot;extreme&amp;quot; values: an empty bucket, a fully loaded truck, and so forth. The exact interpretation of COMPLETION-STATE is the open question that Levin \[1993\] referred to, and that 3ackendoff treated with his 'a' subscript. We do think, though, that an abstract STATE in the domain model, which subsumes a range of the concrete STATES, is preferrable to introducing a primitive on the linguistic level (unless the primitive is relevant, for other linguistic phenomena as well).</Paragraph>
      <Paragraph position="12"> The following alternation rule applies to durative verb readings that denote ACTIVITIES of something being moved to somewhere, and extends them to also cover the POST-STATE, which must be subsumed by COMPLETION-STATE. In this way, it derives reading  loaded hay onto the wagon / Tom loaded the wagon with hay; Jill stuffed the feathers into the cushion / ,Jill stuffed the cushion with tile feathers. The PSemSpec is modified as follows: The former :dest inat ion (wall) becomes the new :actee, whereas the former : ac~ee (paint) now fills the role &lt; : inclusive &gt;, and is optional there, because Jill stuffed the cushion is also well-formed.</Paragraph>
      <Paragraph position="13">  Most of this rule covers two kinds of locative alternation, which Levin distinguishes: the 'spray/load' alternation and the 'clear (transitive)' alternation. The latter applies only to the verbs clear, clean, drain, empty and can be seen as the 'semantic inverse' of the spray/load alternation, because one group of verbs denotes activities of placing something somewhere, and the other describes activities of removing something from somewhere; but both have the same 'holistic' effect in one of the verb configurations. For example, the rule derives Tom drained the container of the water from Tom drained the water from the container) Thus, the rule for the clear- null alternation is the same as the one shown above, with three exceptions: the keyword replacing :acl;ee is not &lt;:inclusive&gt; but &lt;:of-matter&gt;, the DESTINATION in the denotation is a SOURCE, and correspondingly, the keyword :destination is : source.</Paragraph>
      <Paragraph position="14"> The clear verbs, except for to clean, can in addition be intransitive, and Levin states a separate alternation for them. For to dram, the first configuration is The water drained from the tank, and the second is either The tank drained or ?The tank drained of the water. According to Levin, &amp;quot;the intransitive form may be best in the absence of the of-phrase&amp;quot; \[Levin 1993, p. 55\]. The SitSpec denoted by the first configuration is: The water drained from the tank.</Paragraph>
      <Paragraph position="16"> Note that our ducative-causative extension rule given fact has critical influence on the 'holistic' interpretation of mass flollns, above applies in this case and extends the coverage of the SitSpec to one corresponding to Tom drained the water from the tank. A rule that is parallel to that for the transitive case is given below; it derives ?The tank drained of the water; since the &lt; :of-ma'eter &gt; is optional, we can also produce The tank drained, which is, according to Levin, preferred.</Paragraph>
      <Paragraph position="17">  Summary Tile extensions introduced now can apply in a sequential order to a verb. Figure 4 provides a synopsis: The boxes contain the denotation patterns that correspond to the Aktionsart feature, and the rules transform a configuration with one Aktionsart into another. In this graph, every verb base form has an entry point corresponding to the Aktionsart of its most basic configuration. Examples: to fillis STATIVE, to drain is DURATIVE, tO open is TRANSFORMATIVE, to remove is RESULTATIVE-+-CAUSATIVE. The &amp;quot;double box&amp;quot; in the middle is the entry point for both TRANSFORMATIVE and RESULTATIVE verbs, but the incoming arrows produce RESULTATIVE forms.</Paragraph>
      <Paragraph position="18"> From the entry point of a verb, arcs can be followed and rules applied if the respective alternation is specified in the lexical entry. Returning to the example of to drain, figure 5 shows how the rules successively derive the various configurations.</Paragraph>
      <Paragraph position="19"> 4.3 Examples: lexical entries for verbs To illustrate our treatment of valency, argument linking, and alternation/extension rules, figure 6 shows excerpts from lexical entries of eight different verbs. Ttle information is arranged as follows: On the right-hand side is the case frame of the verb, written as the SemSpec participant keywords (each starting with a colon). Optional participants are enclosed in angle brackets. On the left-hand side are excerpts from the denotation: the names of the roles whose fillers are co-indexed with the respective position in the case frame. Thus, the arrows give the argument linking for the base form of the verb, which can be quite simple, as in open or move. From the perspective of the domain model, the roles on the left-hand side of the arrows are required to be filled--as is encoded in the LOOM definitions of the underlying concept. Only items appearing with an asterisk in front of them are optional in the SitSpec: for example, a SitSpec underlying an  OPEN event is well-formed without a CAUSER being present. The optional elements are listed here because they can be verbalized with the extension rules that we have introduced. The names of all the applicable rules (those that we have discussed here) for a verb appear below the line.</Paragraph>
    </Section>
  </Section>
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