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<?xml version="1.0" standalone="yes"?> <Paper uid="P87-1021"> <Title>THE INTERPRETATION OF TENSE IN DISCOURSE</Title> <Section position="4" start_page="149" end_page="152" type="metho"> <SectionTitle> 3. Temporal Focus </SectionTitle> <Paragraph position="0"> In this section, I give a more specific account of how the discourse interpretation of tense relates to e/s structure construction.</Paragraph> <Paragraph position="1"> At any point N in the discourse, there is one node of e/s structure that provides a context for the interpretation of the RT of the next ctause. I will call it the temporal focus or TF. There are three possibilities: (1) the FIT of the next clause will be interpreted anaphorically against the current TF, (2) the &quot;IF will shift to a different node of Ms structure- either one already in the structure or one created in recognition of an embedded narrative - and the RT interpreted with respect to that node, or (3) the &quot;IF will return to the node previously labeUed TF, after completing an embedded narrative, as in (2), and the RT interpreted there, These three behaviors are described by four focus management heuristics described in this section: a Focus Maintenance Heuristic, two Embedded Discourse Heuristics and a Focus Resumption Heuristic. 9 In \[21\], I presented a control structure in which these heuristics were applied serially. The next heuristic would only be applied when the prediction of the previous one was rejected on grounds of &quot;semantic or pragmatic inconsistency'. I now believe this is an unworkable hypothesis. Maintaining it requires (1) identifying grounds for such rejection and (2) arguing that one can reject proposals, independent of knowing the alternatives.</Paragraph> <Paragraph position="2"> I now don't believe that either can be done. It is rarely the case that one cannot come up with a story linking two events and/or Situations. Thus it would be impossible to reject a hypothesis on grounds of inconsistency. All one can say is that one of such stodes might be more plausible than the others by requiring, in some sense not explored here, fewer inferences. ~deg Thus I would now describe these heuristics as running in parallel, with the most plausible prediction being the one that ends up updating both sis structure and the TF. For clarity in presentation though, I will introduce each heuristic separately, at the point that the next example calls for it.</Paragraph> <Section position="1" start_page="149" end_page="152" type="sub_section"> <SectionTitle> 3.1. Interpreting RT against &quot;iF </SectionTitle> <Paragraph position="0"> Before presenting the temporal focus management heuristics, I want to say a bit more about what it can mean to interpret the RT of the next clause against the current TF. This discussion points out the additional advantage to 9Rohrer \[15\] suggest= that ~ere may exist a set of possible temporal referents, possibly ordered by saliency, among which ~e tense in a sentence may find its reference time, but donsn't elaborate how. That is ~a only thing I have seen thin comes close to eta current proposal.</Paragraph> <Paragraph position="1"> ldegCcain arid Steedman \[3\] make a similar argument about prepositional phrase (PP) attachmenL For example, it is not impossible for a cat to own a telescope - e.g., by inheritance from its former owner. Thus &quot;a ~ wi~ a telescope&quot; is not art inconsistent description. However, it must compete with other plausible interpretations like &quot;seeing wi~ a telescope&quot; in &quot;i saw == cat with a telescope'.</Paragraph> <Paragraph position="2"> be gained by pushing the analogy between tense and definite NPs.</Paragraph> <Paragraph position="3"> As I noted above, a definite NP can specify an entity 'strongly' associated with its antecedent. One might thus consider what is 'strongly' associated with an event. One answer to this question appears in two separate papers in this volume \[8, 13\], each ascribing a tripartite structure to the way we view and talk about events. This structure consists of a preparatory phase, a culmination, and a consequence phase, to use the terminology of \[8\]. (Such a structure is proposed, in part, to give a uniform account of how the interpretation of temporal adverbials interacts with the interpretation of tense and aspect.) Nodes in e/s structure correspond to events and situations, as the speaker conceives them. If one associates such a structure with the node labelled the currant TF, then one can say that 'strongly' associated with it are events and situations that could make up its preparatory phase, culmination or consequence phase.</Paragraph> <Paragraph position="4"> Like a definite NP, the RT of tense may either co-specify the current TF or set up a new node in e/s structure 'strongly' associated with the TF. In the latter case, its corresponding event or situation will be interpreted as being part of one of these three phases, depending on the speaker and listener's assumed shared knowledge.</Paragraph> <Paragraph position="5"> Since, arguably, the most common way of perceiving the wodd is as an ordered sequence of events, this will increase the plausibility of interpreting the next event or situation as (1) still associated with the current TF and (21 part of the consequence phase of that event (i.e., after it).</Paragraph> <Paragraph position="6"> On the other hand, this 'strong association' treatment no longer limits anaphorio interpretation to &quot;co-specify&quot; or &quot;right after= as in \[4, 6, 12\]. The event described can be anaphorically associated with the the whole event structure (Example 6a), the consequence phase (Example a. John walked across Iowa. He thought about Mary, who had run off with a computational linguist.</Paragraph> <Paragraph position="7"> b. John walked across Iowa. He crossed the state line at Council Bluffs and headed west through Nebraska.</Paragraph> <Paragraph position="8"> c. John walked across iowa. He started in Sioux City and headed east to Fort Dodge.</Paragraph> <Paragraph position="9"> Deciding which of these three options holds in a given case demands an appeal to world knowledge (e.g. which actions can be performed simultaneously by a single agent). This is yet another area demanding further study and is not treated in this paper. 11 11Mark Steedman shares responsibility for this idea, which is aJso mentioned in his paper wi~ Marc Moons in this volume \[8\].</Paragraph> <Paragraph position="10"> 3.2. Focus Maintenance and Focus Movement The following pair of examples illustrate the simplest movement of temporal focus in a discourse and its link with e/s structure construction.</Paragraph> <Paragraph position="11"> Example 7a 1. John went over to Mary's house.</Paragraph> <Paragraph position="12"> 2. On the way, he had stopped by the flower shop for some roses.</Paragraph> <Paragraph position="13"> 3. Unfortunately the roses failed to cheer her up.</Paragraph> <Paragraph position="14"> Example To 1. John went over to Mary's house.</Paragraph> <Paragraph position="15"> 2. On the way, he had stopped by the flower shop for some roses.</Paragraph> <Paragraph position="16"> 3. He picked out 5 red ones, 3 white ones and one pale pink.</Paragraph> <Paragraph position="17"> Since the first two clauses are the same in these examples, I will explain them together.</Paragraph> <Paragraph position="18"> With no previous temporal focus (TF) established prior to clause 1, the listener creates a new node of e/s structure, ordered prior to now, to serve as TF. &quot;IF sites the anaphoric interpretation of RT 1, which, because clause 1 is in the simple past, also sites ET 1. This is shown roughly in Figure 3-1.</Paragraph> <Paragraph position="19"> Figure 3-1: E/S structure after processing clause 1 The first heuristic to be introduced is a Focus Maintenance Heuristic (FMH).</Paragraph> <Paragraph position="20"> After interpreting dause N, the new TF is the most recent TF - i.e., the node against which RT N was interpreted.</Paragraph> <Paragraph position="21"> The most recent &quot;IF is cotemporal with RT I. This new TF now provides a site for interpreting RT 2. Since clause 2 is past perfect, ET 2 is interpreted as being prior to RT 2. E/s structure is now roughly as shown in Figure 3-2.</Paragraph> <Paragraph position="22"> E't'~ C/'.~z. s&quot;~ E.~\]..</Paragraph> <Paragraph position="23"> Flgure 3-2: E/S structure after processing clause 2 Applying the FMH again, RT 2 is the new TF going into clause 3. Examples 7a and 7b here diverge in what subsequently happens to the TF.</Paragraph> <Paragraph position="24"> In 7a, RT 3 can be anaphorically interpreted as immediately following the TF. Since RT 3 in turn directly sites ET 3 (clause 3 being simple past), the &quot;failing event&quot; is interpreted as immediately following the &quot;going over to Mary's house * event. This is shown roughly in Figure 3-3. (TF is shown already moved forward by the FMH, ready for the interpretation of the next clause, if any.) nk Figure 3-3: E/S structure after processing clause 7a-3 To get the most plausible interpretation of 7b - i.e., where the &quot;rose picking * event is interpreted anaphorically with respect to the &quot;flower shop&quot; event - requires a second heuristic, which I will call an Embedded Discourse Heuristic. This will be EDH-1, since I will introduce another Embedded Discourse Heuristic a bit later.</Paragraph> <Paragraph position="25"> If ET N is different from RTN='rF, treat utterance N as the beginning of an embedded narrative, reassign ET N to TF (stacking the previous value of TF, for possible resumption later) and try to interpret RTN+ 1 against this new TF.</Paragraph> <Paragraph position="26"> By this heuristic winning the plausibility stakes against the FMH, TF is reassigned to ET 2 (stacking the previous TF, which is sited at RT2=RT I=ET 1). and RT 3 is anaphorically interpreted as following this new TF. As before, ET 3 is sited directly at RT 3 (since simple past), so the &quot;picking out the roses&quot; event is viewed as immediately following the &quot;stopping at the florist&quot; event. This is shown roughly in 1. John went over to Mary's house.</Paragraph> <Paragraph position="27"> 2. On the way, he had stopped by the flower shop for some roses.</Paragraph> <Paragraph position="28"> 3. He picked out 5 red ones, 3 white ones and one pale pink.</Paragraph> <Paragraph position="29"> 4. Unfortunately they failed to cheer her up.</Paragraph> <Paragraph position="30"> First notice that clauses 2-3 form an embedded narrative that interrupts the main narrative of John's visit to Mary's. The main sequence of events that begins with clause 1 resumes at clause 4. Now consider the anaphoric interpretation of tense. Clauses 1-3 are interpreted as in Example 7b (cf. Figure 3-4). The problem comes in the interpretation of Clause 7c-4.</Paragraph> <Paragraph position="31"> To get the most plausible interpretation requires a third heuristic which I will call a Focus Resumption Heuristic (FRH).</Paragraph> <Paragraph position="32"> At the transition bade from an embedded nan'alive, the TF prior to the embedding (stacked by an Embedded Discourse Heuristic) can be resumed.</Paragraph> <Paragraph position="33"> Using this heuristic, the previously stacked TF (sited at RT2=RT1-ET 1 - the &quot;going to Mary's house&quot; event) becomes the new TF, and RT 4 is interpreted as directly following it. Since clause 7c-4 is simple past, the &quot;failing&quot; event is again correctly interpreted as immediately following the &quot;going over to Mary's house&quot; event. This is shown roughly in Figure 3-5.</Paragraph> <Paragraph position="35"> Figure 3-5: EJS structure after processing clause 7c-4 I have already noted that, like a definite NP, tense can cause the listener to create a new node in e/s structure to site its RT. What I want to consider here is the circumstances under which a reader is likely to create a new node of e/s structure to interpret RTN.I, rather than using an existing node (i.e., the current TF, one associated with the previous event (if not the TF) or a previous, stacked TF).</Paragraph> <Paragraph position="36"> One circumstance I mentioned earlier was at the beginning of a discourse: a reader will take an introductory sentence like Snoopy's famous first line It was a dark and stormy night.</Paragraph> <Paragraph position="37"> and start building up a new e/s structure with one node corresponding to ST and another node siting RT and ET, Generalizing this situation to the beginning of embedded narratives as well, I propose a second Embedded Discourse Heuristic (EDH-2): If clause N+t is interpreted as beginning an embedded narrative, create a new node of e/s structure and assign it to be TF. Stack the previous value of TF, for possible resumption later.</Paragraph> <Paragraph position="38"> EDH-2 differs from EDH-1 in being keyed by the new clause itself: there is no existing event node of els structure, different from the currant TF, which the embedded narrative is taken to further describe.</Paragraph> <Paragraph position="39"> EDH-2 explains what is happening in interpreting the third clause of Example 4. Even though all the clauses of Example 4 are simple past, with ET=RT, the third clause is most plausibly interpreted as describing an event which has ocoured prior to the *telling about her brother&quot; event. EDH-2 provides the means of interpreting the tense in an embedded narrative whose events may occur either before or even after the current TF.</Paragraph> <Paragraph position="40"> Example 4 1. I was at Mary's house yesterday.</Paragraph> <Paragraph position="41"> 2. We talked about her brother.</Paragraph> <Paragraph position="42"> 3. He spent 5 weeks in Alaska with two friends.</Paragraph> <Paragraph position="43"> 4. Together, they made a successful assault on Denali. 5. Mary was very proud of him.</Paragraph> <Paragraph position="44"> Notice that the focus stacking specified in EDH-2 enables the correct interpretation of clause 4-5, which is most plausibly interpreted via the FRH as following the &quot;telling about her brother&quot; event.</Paragraph> <Paragraph position="45"> EDH-2 is also relevant for the interpretation of NPs headed by de-verbal nouns (such as &quot;trip', &quot;installation', etc.). While such a NP may describe an event or situation, there may not be enough information in the NP itself or in its clause to locate the event or situation in els structure (of. &quot;my trip to Alaska&quot; versus &quot;my recent/upcoming trip to Alaska'). On the other hand, EDH-2 provides a way of allowing that information to come from the subsequent discourse. That is, if the following clause or NP can be interpreted as describing a particular event/situation, the original NP and the subsequent NP or clause can be taken as co-specifying the same thing. Roughly, that is how I propose treating cases such as the following variation of 1. I was talking with Mary yesterday.</Paragraph> <Paragraph position="46"> 2. She told me about her trip to Alaska.</Paragraph> <Paragraph position="47"> 3. She spent five weeks there with two friends, and the three of them climbed Denali.</Paragraph> <Paragraph position="48"> The NP &quot;her trip to Alaska&quot; does not of itself cause an addition to e/s structure. 12 Rather, application of EDH-2 to the interpretation of clause 5-3 results in the creation of a new node of els structure against which its RT is sited. Other reasoning results in clause 3 and &quot;her trip to Alaska&quot; being taken as co-specifying the same event. This is what binds them together and associates &quot;her trip to Alaska&quot; with a node of e/s structure.</Paragraph> <Paragraph position="49"> Rnally, notice that there will be an ambiguity when more than heuristic makes a plausible prediction, as in the following example: It is plausible to take the second utterance as the beginning of an embedded narrative, whereby EDH-2 results in the &quot;talking about&quot; event being interpreted against a new node of els structure, situated prior to the &quot;telling Frank&quot; event. (In this case, &quot;we&quot; is Ira and me.) It is also plausible to take the second utterance as continuing the current narrative, whereby FMH results in the &quot;talking about&quot; event being interpreted with respect to the &quot;telling Frank&quot; event. (In contrast here, &quot;we&quot; is Frank and me.) 1=It does, of course, result in Re creation of a discourse entity \[19\]. The relationship I see between t~e listener's e/s structure and his'her dlacoume model is discussed in \[21 \].</Paragraph> </Section> </Section> <Section position="5" start_page="152" end_page="153" type="metho"> <SectionTitle> 4. Temporal Focus and Temporal Adverbials </SectionTitle> <Paragraph position="0"> So far I have only shown that clauses containing no other time-related constructs than tense can be interpreted anaphorically against more than one site in ale structure.</Paragraph> <Paragraph position="1"> Now I want to show, at least by example, that what I have proposed holds for clauses containing relative temporal adverbs as well. Relative temporal adverbials must be interpreted with respect to some other time \[18\]. So consider the italicized forms in the following brief texts.</Paragraph> <Paragraph position="2"> John became the captain of Penn's squash team.</Paragraph> <Paragraph position="3"> He was previously captain of the Haverford team.</Paragraph> <Paragraph position="4"> John left for London on Sunday.</Paragraph> <Paragraph position="5"> Tuesday he went to Cambridge.</Paragraph> <Paragraph position="6"> Tuesday John went to Cambridge.</Paragraph> <Paragraph position="7"> On Sunday, he left for London.</Paragraph> <Paragraph position="8"> Previously is interpreted with respect to the previously mentioned &quot;becoming captain&quot; event: it was before that that he was captain at Haverford. In the second case, the adverbial On Sunday, given no previous link in the discourse, is interpreted with respect to ST. However, Tuesday is then interpreted with respect to the event of John's leaving for London: it is interpreted as the Tuesday after that event. The third case is the reverse.</Paragraph> <Paragraph position="9"> What I want to show is that, as before, the same four heuristics predict the sites in els structure that may provide a context for a relative temporal adverbial.</Paragraph> <Paragraph position="10"> Consider the following.</Paragraph> <Paragraph position="11"> Example 10a 1. John went over to Mary's house.</Paragraph> <Paragraph position="12"> 2. On the way, he had stopped by the flower shop for some roses.</Paragraph> <Paragraph position="13"> 3. After five minutes of awkwardness, he gave her the flowers Example 10b 1. John went over to Mary's house.</Paragraph> <Paragraph position="14"> 2. On the way, he had stopped by the flower shop for some roses.</Paragraph> <Paragraph position="15"> 3. After 20 minutes of waiting, he left with the bouquet and fairly ran to Mary's.</Paragraph> <Paragraph position="16"> I will use ADV to refer to the interpretation of the &quot;after&quot; adverbial. In these cases, what is sited by TF is the beginning of the interval. What in turn sites the RT of the main clause is the end of the interval.</Paragraph> <Paragraph position="17"> The processing of the first two clauses is just the same as in examples 7a and b. From here, the two examples diverge.</Paragraph> <Paragraph position="18"> In 10a-3, the beginning of ADV is most plausibly interpreted with respect to the TF. The end of ADV in turn provides an anaphoric interpretation point for RT 3. Since ET 3 is interpreted as coincident with RT 3 (clause 3 being simple past), the &quot;rose giving&quot; event is interpreted as immediately following John's getting to Mary's house. This is shown roughly in figure 4-1.</Paragraph> <Paragraph position="19"> Figure 4-1: E/S structure after processing clause 10a-3 In 10b-3, the interpretation due to FMH is less plausible than that due to EDH-I. EDH-1 re-assigns TF to ET2, where the beginning of ADV is then sited. The end of ADV in turn provides an anaphoric interpretation point for RT 3. Since ET 3 is sited at RT 3, the &quot;leaving with the bouquet&quot; event is sited at the end of the twenty minutes of waiting. This is shown roughly in Figure 4-2.</Paragraph> <Paragraph position="20"> ,.._.,_3 laC/>v &quot;t'~&quot; Figure 4-2: E/S structure after processing clause 10b-3 An interesting question to consider is whether a speaker would ever shift the TF as modelled by the FRH or the EDH-2, while simultaneously using a relative temporal adverbial whose interpretation would have to be linked to the new TF, as in example 11 (movement via FRH) and example 12 (movement via EDH-2).</Paragraph> <Paragraph position="21"> Example 11 1. John went over to Mary's house.</Paragraph> <Paragraph position="22"> 2. On the way, he had stopped by the flower shop for some roses 3. He picked out 5 red ones, 3 white ones and one pale pink.</Paragraph> <Paragraph position="23"> 4. After 5 minutes of awkwardness, he gave her the flowers.</Paragraph> <Paragraph position="24"> Example 12 1. I was at Mary's house yesterday.</Paragraph> <Paragraph position="25"> 2. We talked about her brother.</Paragraph> <Paragraph position="26"> 3. After 6 months of planning, he went to Alaska with two friends.</Paragraph> <Paragraph position="27"> 4. Together, they made a successful assault on Denali. 5. Mary was very proud of him.</Paragraph> <Paragraph position="28"> I find both examples a bit awkward, but nevertheless understandable. Accounting for TF movement in each of them is straightforward. However, whether to attribute the awkwardness of these examples to exceeding people's processing capabilities or to a problem with the theory is grist for further study.</Paragraph> </Section> class="xml-element"></Paper>