<?xml version="1.0" standalone="yes"?>
<Paper uid="W93-0235">
  <Title>Rhetorical Relations, Action a,nd Intentionality in Com:ersation*</Title>
  <Section position="1" start_page="0" end_page="132" type="abstr">
    <SectionTitle>
Abstract
</SectionTitle>
    <Paragraph position="0"> This paper contains an investigation of the relationship between rhetorical relations and intentions. Rhetorical relations are claimed to I)e actions, and thus the prolmr objects of intentions, although some relations may occur \])e independent of intentions. Explicit identification of particular relations is shown to I)e not always m~cessary when l.his information~ can be cal)tnred in other ways, nevertheless, relations are often useful I)oth in plamfing aml r~cognil,ion.</Paragraph>
    <Paragraph position="1"> Rhetorical Relations and Intentions There are a number of different types of relationships between l)roxima.te segments of language, as well as a number of terms used to dif|erentiate groups of these types. For the present l)Url)oses I make no distinction (as do, e.g. \[Sidner; Moser a.nd Moore\]) 1)etw(,en afflictive and other types of discourse coherence relations. Since my primary interest is lit conversation (rather than, say, single producer text), I also include relations between utterances by (lilli:rent sl)eakers. Another dimension along which a distinction couhl be made is what exactly i.s being related'/ Are relations between explicit spa.ns of language text or between elements of the expressed contents of texts or perhN)s mixes between these categories? Aga.in, I will not make any such distinctions here, and simply use the term rhetorical relations to refer to any of these relations.</Paragraph>
    <Paragraph position="2"> As with other types of linguistic meaning, there are both Semantic and Pragmatic views of rhetorical relations. Semantic views concentrate on whether or not a relationship can be inferred fl'om features of the discourse and whal: other in|brmation can 1)e inferred when the relation hol(Is or does not. Pragmatic views are more concerned with how a rela.ti(mshil) is established and what effects this relationship (or lack of relationshil) ) has on the context) For the purposes of engaging in conversation and relating rhetorical relations to intelltiorts, I take the pragmatic viewpoint as more central, although both are iml)ortant.</Paragraph>
    <Paragraph position="3"> From the pragmatic viewpoint, rhetorica.\] relations are the same general kind of thing as speech acts or actions in generM: al)stractions of agent-directed change in the worhl, in this case change in the conversational and metM state of the col.,versallts. The only difl'(qence between speech acts and rhetoricM relations is that the latter a.re exl~lMtly concerned with the linka.gC/, of separate segments of language. \['I~'aum and Hinkehnan, 1992\] presents a nmltistra.tal tlteory of Conversation Acts, *This material is ha.ted upon work supported in part by the NSF under research gr;tnt ltO. IRI-9(1\[13841, by ONR under research grant no. N0{I014-9(I-J-1811, alld I)y DARPA/ONR under contract Nlllllll4-.q2-J-1512. l wouhl like to thank James Allen and Peter Heeman for helpfid discussions.</Paragraph>
    <Paragraph position="4"> 1This distinction iv also discussed by \[Maylmry\] a.s the distinction between rcl, tion.~ and act.i, although here I will use these terms more or less synollylnously.</Paragraph>
    <Paragraph position="5">  which includes both traditional sl)eech acts and several kinds of rhetorica.l arts. There are low level acts which link together utterances into turns a.nd content into units which axe acknowledge(i a, nd understood together, as well as a level of a~yumt:nlation acts which link together 1)roposition level and larger illocutionary acts. Argumentation acts include act types such a,s ans'wcriug a questiou, as well as most traditional rhetorical relations.</Paragraph>
    <Paragraph position="6"> Actions play a useflfl role as ,% concel)tual intermediary between bundles o\[&amp;quot; &lt;)l)serve(l features on the one hand, and stereotyl)ica,1 causes a.nd efl'ects. They are ;Llso the \])rol)(~r ()l)jects of intentions, and play a central role in planning, l)lan execution an(I l)lan recognition. PI;i.nning is the process of selecting a set of actions which, when 1)erforme(l under the prol)er conditions will lea,(l to a.</Paragraph>
    <Paragraph position="7"> desired state of affairs, or goal. Plan execution is the process of pertbrming the designated actions, monitoring them for desired effect ~uld repairing or replanning in case of a, l)rol)lem. Plan recognitiou is the process of reasoning ahout an agent's menta,1 state (including intentions, beliet~, an(1 goals) based on observed actions in context.</Paragraph>
    <Paragraph position="8"> Intentions are commitments towards a course of action. \[Bratnlan, 1990\] discusses three roles that intention plays in deliberative behavior: serving a,s a motivation for l)lanning, a &amp;quot;filter of admissil)ility&amp;quot; on plans and 51rther intentions, a,nd a controller of (:on(luct, motivating execution monitoring and tel)air and rel)lanning when necessa.ry.</Paragraph>
    <Paragraph position="9"> Rhetorical relations are thus actions in the worhl (listinguishe(l 1)y conditions on their occurrence and effects, which will generally l)e changes to the conversational state all(I the I)eliefs of the conversants. Relations can also be 1)lanned, intended, performed, and recognized. As with other actions, relations can be performed intentionally or incidentally. Of intentiona.l a.ctions, it is also possible to draw the distinction made in sl)eech a.ct theory between illocutionary acts, those in which part of the intended effect includes a.n awa.reness on the t)art of the hea, rer ()1&amp;quot; this intention, and pcrlocutiouary acts, in which it is only the efi~ct that ma.tters a.n(l not recognition of the intention \[Austin, 1962\].</Paragraph>
    <Paragraph position="10"> For non-illocutionary acts, the intention of the speaker is not relevant - these actions can be produced as side-effects of the speaker's intention, so that a determination of the intention is not necessary to determining whether the act was 1)eribrmed. For exa,ml)le, the evidence relation of \[Mann and Thompson, 1987\] may hohl \])etween two text spans even if the speaker di(l not inten(I such a relation, all that is required is that tlm hea.rer's belief in the nucleus is increase(I though the understanding of the satellite. For an illocutionary act, on the other hand, the recognition of communicative intention is crucial to understanding. For exa.mple, the answer relation can only be recognized by attributing to the speaker the intention to answer the question.</Paragraph>
    <Paragraph position="11"> Is Identification of Rhetorical Relations Necessary? It is on the following point that tile main criticisnl of bounded sets of sl)e('ch acts or rhetori('al relations (e.g. \[Cohen a,nd Levesque, 1990; G rosz a, nd Sidner, 1986; Lochba.u m; I! ughes a,nd Mc(',oy\]) is centered: intuitively, all that is needed tbr successful communica,tion is tha.t the hearer understand the speaker's end intentions, not that the a.ct types themselves be rec()gniz(,d. This intuition, along with the lack of general agreement on the precise set of acts or rela.tions lead some to reject the utility of relations aJtogether and concentra.te only on intentions. While I ha.re some sympathy fi~r this view, relations are often convenient for inh~re,tia.l purl)oses. It is not so iml)ortant that the particular set of relations use(I 1)e the &amp;quot;right&amp;quot; set, or even tha.t the s(,t be sha.r(~d by tim discourse participants, a.s long as both pa.rticipa.nts can r~a.ch a. ha.sic a.gre(~nmnt t)n t.h(~ inl.~md~d ~fli~rts. Still, relations prove to be a. conveni(~nt intcrm(~(lia.ry b(q.w(~cLi rea.soning a.bout high leve |int, entions a.nd actual surf~tce forms.</Paragraph>
    <Paragraph position="12"> In light of the preceding discussion, the question of whether rhetori(:al rela,tions must be identi: 133 fled can be broken down into two subquestious. On the one ha.nd, if we are talking about whether the semantic relationship is inferable from the resulting discourse representa,tion, the answer must he yes for illocutionary relations. On the other hand, it may not 1)e necessary to explicitly recognize the act itself in the interpretation process - this knowledge may be iml)licit within the representation.</Paragraph>
    <Paragraph position="13"> As an example, \[Moser and Moore\] discuss a ro-specificaliou relation which hohls between two propositions which refer to the same entity. Thry only consider relati~us which &amp;quot;must be recognized in order to understand the discourse&amp;quot;, yet it seems l)erfectly pla.usil)l(, to claim that an agent couhl recognize that the propositions pl and 1)2 refer to the same entity E without necessarily representing or noticing any relationship 1)etween pl and p2 (though this relationship would be deducible from the individual designations of pl and p2).</Paragraph>
    <Paragraph position="14"> Rhetorical Relations in the TRAINS System In the TRAINS Conversation System implenmntation \[Allen and Schubert, 1991\], we take a fairly pragmatic approach towards rhetorica.1 relations. Those relations that are conventiona.lly signalled by surface features (e.g. by clue words such a.s &amp;quot;so&amp;quot;, &amp;quot;no&amp;quot;, &amp;quot;okay&amp;quot;, purpose clauses) are hypothesized by the Speech Act Interpreter \[Heeman, 1993\] and used by the DiMogue Manager \[Tra.um, 1993\] to guide further interl)retation. In the case of more implicit relatiol,ships wr often (Io not identify the precise relation, merely operating on the sl)ee('h act level tbrms. ()f (:ourse, r(,la.tions (:ould be id(mtilied based on how the content is treated with rcspect to l)revi(~us conteut, but that doesn't seem helpful presently. This is particularly true tot subject matter relations. For example, a purpose clause is nseflfl ior the domain plan recogMzer \[Ferguson anti Allen, 1993\] in incorporating new content into an existing (partial) plan, but in the absence of such a cue, the recognizer will still try to connect the new content to 1)revious content. It wouhl then 1)e possible to deduce the relations that this item hohls with 1)revious items, but we currently see no need to do this. As an example, consider the following possible pair of utterances in a situation in which the expressed content is not already in the current plan~ but is easily incorl)orated:  (1) Move Engine E1 to Dansville to pick Ul} the boxca,r there, ...</Paragraph>
    <Paragraph position="15"> (2a) Move Engine E1 to Dansville, (2b) pick up the boxcar there ....</Paragraph>
    <Paragraph position="16">  In (1), the &amp;quot;to&amp;quot; clause would lead the Sl)eech a.ct interpreter to pr(q)ose a PURI)OSE relation, while no Such relation would be proposed fi)r (2). (1) might have wider applicability (e.g. in a case in which it is already known tha.t the boxcar a.t Dansville will be moved) and may be easier to incorporate into a current plan structure (e.g. for (2a) the planner might choose a different reason for moving El), but in the current case these utterances would end u l) with identical plan structures. Now if relation identification were an explicit task of the system, we could say that a purpose relation was deduced (there a.re of course other possibilities, such as SEQUENCE), though currently we see no need to assign a particular rela.tion or set of relatiolLs.</Paragraph>
    <Paragraph position="17"> Conclusions Smuming up, rhetorical relations, like speech acts, are abstract actions and thus tile prol)er object of intentions. They may realize intentions, Mthough, Like other actions, some may be performed without having been intended (e.g. as side effects of actual intentions). Rhetorical acts have  as their direct effect a change in hearer's belief (and speaker's belief about hearer's belief, etc.). The conversational and mental state will also be cruciM in determining whether relations actually hold hetween segments of language. Identification of relations can often be usefltl in discourse understanding, but is not Mways strictly necessary, as several sets of relations Inight lead to the same results, and often it is not possible to identit), the particular relation uutil after calculating effects, in which case there is no flu'ther need tbr labelling the relation. Which set of relations should be part of the working ontology is still an open (luestion, Mthough I wouhl suggest that an approach toward this question wouhl be to use only those relations which seem useful in interpreting and producing text.</Paragraph>
  </Section>
class="xml-element"></Paper>