=Paper=
{{Paper
|id=None
|storemode=property
|title=Toward a Discourse Structure Account of Speech and Attitude Reports
|pdfUrl=https://ceur-ws.org/Vol-954/paper18.pdf
|volume=Vol-954
}}
==Toward a Discourse Structure Account of Speech and Attitude Reports==
https://ceur-ws.org/Vol-954/paper18.pdf
Toward a Discourse Structure Account of Speech
and Attitude Reports
Antoine Venant1,2
1
Laboratoire Parole et Langage
2
Ecole Normale Superieure de Cachan
Abstract. This paper addresses the question of propositional attitude
reports within Segmented Discourse Representation Theory (SDRT). In
line with most SDRT discussions on attitudes reports, we argue that the
reported attitude should be segmented in the same way as the rest of the
discourse is. We identify several issues that are raised by the segmenta-
tion of attitude reports. First, the nature of some relations crossing the
boundaries between main and embedded speech remains unclear. More-
over, such constructions are introducing a conflict between SDRT’s Right
Frontier Constraint (RFC) and well established facts about accessibility
from factual to modal contexts. We propose two solutions for adapting
discourse structure to overcome these conflicts. The first one introduces
a new ingredient in the theory while the second one is more conservative
and relies on continuation-style semantics for SDRT.
1 Introduction
From a semantic perspective, attitudes reports require to solve several notorious puz-
zles. Among these, are a lot of problems triggered by definites: Substitution of directly
co-referential expressions is generally not allowed under the scope of an attitude verb
and neither does existential generalization(see the shortest spy problem raised by [8]).
Closely related to those are effects of attitudes verbs on discourse referents availability.
For instance factive epistemic verbs like ’to know’ allow referents introduced under
their scope to be then referred from outside their scope, while non factive like ’to be-
lieve’ do not. These two issues are related to context which has naturally led to several
accounts involving dynamic semantics such as [1, 9].
From the modeling text coherence perspective, we need to understand how report-
ing someone’s propositional attitude interacts with the overall discourse structure. The
dynamic framework of Segmented Discourse Representation Theory (SDRT) [3] allows
to address both perspectives simultaneously by looking at the interaction between dis-
course structure and anaphoric phenomena. However there is in SDRT no semantic
contribution for attitudes report that is as precise as the ones cited above and formu-
lated within Discourse Representation Theory (DRT) [7]. Since SDRT builds over a
lower-level formalism (DRT), and enriches it by adding rhetorical relations, one may
wonder whether DRT-style accounts could be straightforwardly embedded in SDRT.
One condition for this is that SDRT keeps the benefits of the work done in the cho-
sen low-level logic, and uses its ability to handle discourse relation to model a more
R.K. Rendsvig and S. Katrenko (Eds.): ESSLLI 2012 Student Session Proceedings, CEUR Work-
shop Proceedings vol.: see http://ceur-ws.org/, 2012, pp. 170–179.
Discourse Structure of Speech and Attitude Reports 171
accurate interface between semantics and pragmatics.3 We want to address then the
question of how does SDRT’s treatment of embedded speech acts keeps up with such
a consideration.
We attach a particular attention to examples in the spirit of 1 for they involve
irruption of the factive context into the modal context at the discourse level. We think
that such anaphoric links are not fully modelled by the current analyses of attitude
reports in SDRT. Distinguishing between Intentional/Evidential uses of reportative
verbs still do not allow them in some intensional cases while DRT based approaches
would very likely allow event correference from an embedded DRS to the main DRS.
Example 1. The criminal parked his car somewhere near the airport. So detectives
think that afterwards he tried to get into a plane.
After briefly introducing SDRT in section 2, we argue in section 3 for segmentation
of reported constructions. Section 4 deals with relations that links a reported speech
act to a factual one. It shows that the discursive structure of intensional reports is
closed to incoming relations, but still can bear anaphoric links to the context. On this
basis it exhibits a family of relations for which RFC makes bad predictions. Section 5
presents two ways of restoring the right accessibility conditions while still benefiting
from SDRT specificities.
2 Segmented Discourse Representation Structures
SDRT assumes that to analyze discourse one has to segment into meaningful units that
shall be linked to each other by means of discourse relations. Each segment is called an
elementary discourse unit (edu). The level of segmentation is merely the clause level
(where a clause can be understood as something containing an event or a state)4 .
Each discourse unit is assigned a label (πi ,...πn ) in the language of SDRSs and a cor-
responding formula in a given language for representation of atomic clauses (K1 ,...,Kn )5 .
These labels will serve as arguments of rhetorical relations, like narration(πi , πj ) or
explanation(πi , πj ). Additional labels are associated with complex structured content
made of rhetorical relations and other subordinated labels. Such labels with complex
content will be called complex discourse units and recursively used as argument of other
relations. A SDRS is a triple hA, F, Lasti where A is a set of labels (A), F a function
mapping labels to contents (either lower-level language such as DRS or discourse re-
lations in case of complex constituents) and Last the information of the last segment
introduced. (See [3]:p.138 for the precise definition).
SDRT makes a structural distinction between coordinating and subordinating re-
lations. The former, like narration, confer an equal status to their two arguments. The
latter introduce a hierarchy between the related constituents. Such a distinction allows
to define the so-called Right Frontier constraint. The Right Frontier is the set of labels
RF = {π | π ≺∗ Last} where ≺∗ is the transitive closure of the dominance relation
≺ defined by π ≺ α iff α is a complex consitutent which immediately outscopes π or
3
This is indeed what the theory aims at doing while extending DRT’s definition of
accessibility.
4
How fine-grained segmentation should is still under discussions. The present work
is also a contribution at this level since we argue for segmenting attitudes.
5
This is the lower-level language and associated representations.
172 Antoine Venant
there is subordinating edge R(α, π) in some constituent γ. The Right Frontier Con-
straint stipulates that labels accessible for discourse continuation are those of the Right
Frontier, while the ones accessible for correference have to be DRS-accessible on the
right frontier.
For instance, the structure of [John visited his friend]a . [Then he went to the
cinema]b . [He watched Pirates of the Caribbean]c is narration(πa , elaboration(πb , πc ))
elaboration is a subordinating and narration a coordinating relation, therefore the right
frontier is {πb , πc } and the discourse could not be felicitously continued by They talked
for a long time which intends to attach to a.
narration
πa π1
πb
elaboration
πc
Fig. 1. SDRS example
Figure 1 gives a graphical representation of this example, with the convention that
coordinating relation are drawn horrizontally, subordinating one vertically, complex
constituents are linked with dashed edges to their subconstituents, and nodes of the
right frontier are red.
The truth conditional content of an SDRS, as in DRT, is expressed in terms of
context-change potential (i.e relation between world-assignment pairs), and is recur-
sively computed using the semantic constraints associated with each rhetorical relation,
finally relying on the lower-level logical forms.
In this framework, we now move to the discourse structure of attitude and speech
reports.
3 Segmentation and treatment of the matrix clause
There are at least two reasons for capturing the interaction between attitudes or speech
reports and discourse structure. First, we need to account for discourse phenomena both
inside the reports and across their boundaries. Then the treatment of intentional and
evidential uses of attitude reports in the way of [6] also require segmentation.
About the first point, example 2 is not felicitous, because the pronoun ’it’ cannot
easily refer to the salmon in the given context. Such a behaviour is predicted by RFC.
Therefore, even if the semantics of attitudes generally involves quantification over in-
tensions or contents, and thus erases to some extent the structure of the logical form
of the original speech act, the discourse structure of the report is needed anyway to
build the logical form of the speech report.
Example 2. #John told me that Marry had a wonderful evening last night. He said
[she ate salmon]a [and then won a dancing competitionb ] [and that it was beautiful
pink.]b
Discourse Structure of Speech and Attitude Reports 173
On the other hand, in example 3 the reported speech introduces a narration between
two events while the non-reported discourse asserts a causal relation (result) between
the two same events. The contrast introduced by but is however coherent, partially
because it is supported by the isomorphic structures of the reported speech and the
non-reported one. SDRT treatment of contrast as a scalar relation, following [2, 3]
provides such an analysis, assuming that the structure of the embedded speech is
accessible.
Example 3. John says that he left after Mary did but he left because she did.
About the segmentation of the matrix, we may consider the matrix clause as nothing
more than a kind of logical operator6 . However, that would be inaccurate since the
matrix clause can be fairly sophisticated. It generally includes a communication event
or a mental state that can be modified by adverbs or prepositional phrases and therefore
would be difficult to model as simple logical operator. Since removing the matrix-clause
from the discourse representation is not an option neither segmenting attitude reports
forces us to deal with this matrix-clause segment.
[6] addresses several issues raised by such a treatment of reported speech. The
approach consists in segmenting apart matrix clause and reported speech and in iden-
tifying the relation between these elements themselves but also their relations with the
surrounding context. It distinguishes between two uses of reportative verbs, namely ev-
idential where the embedded content is asserted by the main speaker and intensional
where the content of the report is not asserted by the main speaker. In evidential uses,
the matrix clause is subordinated to the embedded content by a veridical evidence re-
lation.7 In intensional uses, the embedded content is subordinated to the matrix via a
relation of attribution which is non-veridical. Such a distinction makes very profitable
the separation of the matrix clause and the reported speech, accounting for cases like
4.
Example 4. (1) [The neighbours are gone.]a [John told me that]b [they went on vaca-
tion in an expensive hotel.]c [I called it this morning.]d
(2) [The neighbours are gone.]a [John told me that]b [they went on vacation in an
expensive hotel.]c [But he lied]e .
As [6] argues, we can see in the first example above that c is asserted by the speaker
since d is carrying an anaphoric link to the hotel eventhough it has first been introduced
under the scope of the attitude8 . On the contrary, in 4.2, the author disagree with what
is reported, and the existence of the hotel is not ensured anywhere outside the scope of
the attitude. Therefore The hotel shall not be referred to later in the discourse. [6] also
argues that the compositional semantics of both the reported speech and the matrix
clause do not change from an intensional to an evidential report. And the matrix clause
can neither be deleted without loss of compositional content in the one nor the other
case. But the way the two parts of speech are related can change. Fu rthermore, since
6
This would still requires to modify the SDRT framework since all logical opera-
tors are delegated either to the lower-level logical forms or to the semantic effects of
discourse relations.
7
To be satisfied, veridical relations require their arguments to be true in the model.
Non veridical relations do not have this requirement. [3]
8
At least if we assume that d is not part of what John said here, but in that case
that it would be a very odd reading.
174 Antoine Venant
the two first sentences are the same in both examples, the decision of choosing the one
or the other might only be a matter of context, as such it is essentially information
packaging, and in SDRT, this level is kept aside from the logic of information content.
Following this analysis, in the first example, d will be related to c by a veridical
relation of narration, forcing the evidential reading. So c will be related to b with the
veridical Evidence(c, b) and to a with a veridical relation of explanation. In the second
example however, continuation e is attached to the whole report with a contrast and
yields an intensional reading (attaching e to the embedded clause only would entails
that John said something incoherent, which is less likely the intended meaning) and
b is related to c using the non-veridical attribution(b, c). The two different type of
structures are sketched below. (Left column is evidential, right one is intensional. We
also give some of the semantics conditions associated with the two relations involved).
φ φ
F(πb ) = F′ (πb ) =
A(x, φ) A(x, φ)
F(πtop ) = Re (πa , πc ) ∧ evidence(πc , πb ) F′ (πtop
′
) = Ri (πa , πb ) ∧ attribution(πb , πc )
Φevidence(πc ,πb ) ⇒ Kπc ∧ Kπb ∧ φ ∼ˆπc Φattribution(πb ,πc ) ⇒ Kπb ∧ φ ∼ˆπc
Where ∼ may be understood as an equivalence relation between SDRS contents.
How this content and ∼ are defined actually remains an open question. Basically content
could be understood as the context change potential. However, blocking substitution of
logically equivalent expressions under the scope of an attitude verb may require some
amount of structure being kept in the notion of content([1]).
4 Relations across boundaries
As [5] remarks, the picture becomes more complicated when relations comes to cross
the boundaries of an embedded speech act such as in 5.
Example 5. [Fred will go to Dax for Christmas]a . [Jane claims that]b [Afterwards, he
will go to Pau]c .
Afterwards introduces a veridical relation of narration. If we invoke the eviden-
tial/intensional distinction and assume an evidential reading, this example does not
pose any problem since the discourse producer (DP ) is thought to assert the content
πc and thus can use a veridical relation for relating it to the context. However, with
an intensional reading the speaker does not claim narration(πa , πc ) since he does not
assert the content of πc . But he still can commit to Jane committing to such a relation.
To solve this problem, [5] set up a new paradigm for discourse analysis that examines
reported relations against several sources. For instance, 5 will be analyzed as follows:
The discourse producer is certain of the main eventuallity ea in a but he does
not know anything about the one in c. Jane is attributed to be certain about the
main eventuality in c, and, after the source of the narration is identified to being
Jane, the picture is completed with the statements of Jane being certain of ea too, as
well as ea and ec being in a temporal sequence. Semantically speaking, such examples
require some further discussion. First, we cannot always identify a source for a relation.
Consider a two level deep embedding as in 6. Asserting narrationFred’s wife (πa , πd ) in
this case would make us unable to distinguish between 6 and the same without b.
With 6 the writer does not commit to Fred’s wife committing that he will go to Pau.
Discourse Structure of Speech and Attitude Reports 175
Example 6. [Fred will go to Dax for Christmas]a . [Jane told me that]b [according to
his wife,]c [afterwards, he will go to Pau]d .
Besides, interpreting narrationJ (πa , πc ) ∧ attribution(πb , πc ) requires some preci-
sions that the framework does not provide. To this end, we may switch to a dialogical
framework in which each individual would receive its own SDRS. However, reducing
reported speech and other voicing effects to dialogue is not what we want to do (espe-
cially if we want to be able to account for 6). Another way to provide an interpretation
would be to use [10] semantics, R(a, b) : JC(Speaker(b), Ka ) ∧ C(Speaker(b), Kb ) ∧
C(Speaker(b), φR(a,b) )K where C is a commitment relation and R a veridical relation.
But once again the structure is misleading, and with this account, the narration pro-
ducer must be understood as being Jane, which is strange since even when being
reported, its producer remains the main producer. And we would end up with a fomulla
entailing C(Jane, φnarration(πa ,πb ) ) instead of something like C(W, C(Jane, φnarration(πa ,πb ) ))
that would be needed to account for example 6 with this semantics. Our conclusion
thus is that the problem originates from the structure which does not model the right
scope of attribution which should includes the narration relation. This can be done in
SDRT by introducing a complex segment for representing the embedded content9 :
A = {πtop , πa , πb , γ, πc }
(1)
F(πtop ) = attribution(πb , γ) F(γ) = narration(πa , πc )
Equation 1 is actually missing a non-embedded left-veridical coherence relation
between πa and another segment. As it stands our structure semantics does not imply
that the main discourse producer claims the content of a. However, more generally there
must be some relation (R) introduced by the main producer and that links πa with the
speech act of reporting Jane’s claim (at least with an intensional reading). Attribution
being subordinating in the intensional case, R cannot be coordinating without the
RFC being violated in 5. So it seems that R should be a subordinating like background.
However cases like 7 are source of problems.
Example 7. (1) [The train arrived 3 hours late.] [then the company announced that]
[in consequence, the passengers would be refunded]. [But as a matter of fact, they
never were.]
(2) [John had a deadline at midnight yesterday.] [So we all though that afterwards he
would go to bed.] [But he did not.]
(3) [Yesterday, John fell three times in a row.] [Mary then told him that] [it was
probably because he drank to much.] [He did not believe her.]
All these examples involve an intensional attitude report and in all of them, lexical
markers mark either a narration or a result between the first segment and the matrix
clause of the report. Finally, they also all seem to support anaphoric links between the
reported content and the first segment. Both result and narration are thought to be
coordinating relations. So even if we use the subordinating background between πa and
πb in 5, we cannot account for these links without violating RFC.
Examples in 7 thus allow us to see that the Intensional/Evidential treatment comes
with the side effect of sometimes preventing from linking to the previous discourse. But
9
Representing SDRS as directed acyclic graphs as it is often done is very confusing
in this case, because a graph based representation does not distinguish which complex
segment actually hosts such a cross-relation. The graphs for our structure and the
problematic one are the same.
176 Antoine Venant
they are very specific in the sense that they enforce an explicit rhetorical link from the
previous discourse on the two level (the main discourse, and the embedded one) at the
same time. The problem may however be more general if these links may as well be
implicit.
Example 8. (1) [The factory blew up.]a [John told me]b [there were a lot of dangerous
chemicals in there.]c
(2) [The factory blew up.]a [John thinks]b [there were a lot of dangerous chemicals in
there.]c
(3) [The factory blew up.]a [John thinks]b [there were a lot of dangerous chemicals in
there.]c [But sam thinks]d [someone lighted a fire.]e
Examples in 8 intend to illustrate this. The first one does not seem to require an
implicit relation between a and c. The possible explanation of the explosion by the
presence of chemicals is not a mandatory part of what John said. Actually John might
have said that to the writer even before the explosion happened, and the writer is
making the link himself from what John previously said. The two other examples on
the other hands may carry such implicit links between a and the reported content b:
There is at least one plausible reading for the second example involving a coordinating
relation between a and b which fits very well an implicit explanation between a and
c. The explosion actually made John think of a plausible explanation, which is that
they are dangerous chemicals in the usine, and that these chemicals may have cause
the explosion. Finally, the last example requires implicit explanation relations to make
a better sense of the con trast relation that links b and c. The beliefs of John and Sam
are fully compatible, unless what John and Sam respectively said is explanation(a, c)
and explanation(a, e), in which case they are not.
All together, this threatens to make SDRT better understanding of anaphoric links
in attitude reports only come at the price of some wrong predictions in some intensional
cases.
5 Restoring accessibility
We have shown that SDRT damages more standard but essentially correct accounts
of anaphoric links going between modal and factual contexts. An account of attitude
reports in DRT for instance, would not have this behaviour. Examples like 7 would
introduce reference to events in the main DRS from the modal context, which is per-
mitted. We would like such a behaviour, but with SDRT treatment of accessibility still
applying inside the reported speech. To this end, we could drop the attribution relation,
falling back to a DRT like treatment. The structure of one of our problematic report in
SDRT would thus be sketched by Rcoord (πa , πatt ) with F(πatt ) = Kπb ∧A(x, φ)∧φ ∼ˆπc .
This structure allows referents in πc to attach or refer to elements in πa .10 This builds
on intensional report being ” closed” discursive structures. We showed in section 4
that a relation cannot really penetrate the report from the factual context without (a
”copy” of) its left argument and itself being embedded under the attitude. Moreover,
attachment to the matrix clause and attachment to a complex segment made of both
the matrix clause and the report are semantically and dynamically equivalent. This
allows us to abstract the complete speech act of reporting under a complex segment
10
Such an approach actually needs to slightly modify the syntax of the SDRS lan-
guage
Discourse Structure of Speech and Attitude Reports 177
πatt . This approach however requires to adapt the language for inferring the relations
because the intensional and evidential cases are now asymmetric. One has to state that
the content of a segment πmat in the evidential case is equal to a part of the content
of the abstracted complex segment πatt in the intensional case.
That is why we propose below a more conservative approach that makes use of
continuation-syle semantics [4]. Continuation style semantics represents a discourse as
a λ−abstraction of type JΓ K = γ → ((γ → l → t) → l → t) where γ is the type of input
contexts. A discourse thus asks for (i) an input context i of type γ containing the effects
of processing the previous discourse; (ii) a continuation o of type γ → l → t representing
the discourse to come and; (iii) a label π, the label of the SDRS representing the whole
discourse.
To represent chunks of an SDRS, a language is used where every n−ary becomes an
n + 1-ary predicate, the extra argument stands for the label that hosts the predicate:
A label π with F(π) = R(π1 , π2 ) will be represented as ∃π1 ∃π2 ∃πR(π1 , π2 , π).
We will assume that the context contains a structural representation of the SDRS
for the previous discourse such that the following functions may be defined:
(1) sell : γ → l that selects a label for attachment.
(2) ν : γ → l → γ that performs the SDRT update operation on the context [3],
defined in terms of SDRT’s language for inferring relations. Given a label π, it
basically picks up a relation and two other labels π1 , π2 in the context and add
the relation R(π1 , π, π2 ) to the context.
Finally, we will use the following version of the binder rule to join a discourse and
a sentence:
JD.SK = λioπ ∃ πD JDKi(λi′ ∃πS JSK i′ o πS ))
The main idea, is to refine [6] proposal of a lexical entry for attitude reports using
continuation-style semantics to overcome the right-frontier problems. Since evidential
and intensional readings only differ by the way the matrix clause and the embedded
content are related, one simple solution is to postpone attachment of the matrix clause
until the embedded content has been dealt with and all attachment to previous context
have been done. But it must be performed before the following discourse is processed
in order to still benefit from the intensional/evidential distinction. This might be done
by modifying the continuation of the report in such a way that it proceeds to the
attachment of the matrix clause before applying the real continuation.
Let us assume an attitude α in a discourse ”x α that φ” and that syntax delivers
us a parse leading to α(x, φ). We add the lexical entry given in 2 for an attitude verbe
α, with A a modal operator corresponding to attitude α.
JαK = λxλsλioπmatt ∃ φA(x, φ, πmatt ) ∧ ∃πs φ ∼ πs ∧ s i [λi′ o(ν(ν(i′ , πmatt ), πs ))] πs
(2)
Let us now have a look back to [The train arrived late]a . [Then the company an-
nouced that]b [the passengers should thus be refunded]c .
We assume for a a lexical entry like:
λioπ ∃x train(x, π) ∧ Late(x, π) ∧ o ν(i, π)
.
178 Antoine Venant
In this entry the update operation ν(i) will deliver a context i′ containing the
structure πa | F (πa ) = [x | train(x) ∧ late(x)], and maybe a relation linking πa to the
previous context. Assuming the lexical entry for Thus is
JthusK = λioπs s i (λi′ Result(selL (i′ ), π, selL (i′ )) ∧ o i′ )
We end up with the following entry for the embeded content c:
λioπ∃y, z ∧ T he P assengers(y, π) ∧ Be Ref unded(y, π)
∧ Result(selL (i), π, selL (i)) ∧ o i
The lexical entry for to announce (our α here) will be given the company as its
first argument and the interpretation of c as its second. Which should yield after beta
reduction:
λioπmatt ∃ φA(The company, φ, πmatt ) ∧ ∃πs φ ∼ πs
∧ ∃y, z ∧ T he P assengers(y, πs ) ∧ Be Ref unded(y, πs )
∧ Result(selL (i), πs , selL (i)) ∧ o(ν(ν(i, πmatt ), πs ))
When composing with JaK, this entry will receive the context i′ containing the struc-
ture πa | F (πa ) = [x | train(x) ∧ late(x)], unmodified, as input context and thus be
able to select πa as first argument for the result relation without RFC violation. Impor-
tantly, successive call to the ν function will perform the intensional/evidential choice
and choose a relation to link the report to the preceding discourse before processing
the continuation.
6 Conclusion
Segmenting discourse structure cannot be avoided, but as we have shown, the discourse
structure of segmented reports is not straightforward. We have thus given a more precise
picture of what it should be and why. It remains to give a precise semantics to those
reports, and especially to decide what is the content ˆπ of a SDRS and what amount
of structure it carries.
References
1. Asher, N.: A typology for attitude verbs and their anaphoric properties. Linguistics
and Philosophy 10(2), 125–197 (1987)
2. Asher, N., Hardt, D., Busquets, J., Sabatier, I.P.: Discourse parallelism, ellipsis,
and ambiguity. Journal of Semantics 18, 200–1 (2001)
3. Asher, N., Lascarides, A.: Logics of Conversation (Studies in Natural Language
Processing). Cambridge University Press (Jun 2005), http://www.worldcat.org/
isbn/0521659515
4. Asher, N., Pogodalla, S.: SDRT and Continuation Semantics. In: Onada, T., Bekki,
D., McCready, E. (eds.) New Frontiers in Artificial Intelligence JSAI-isAI 2010
Workshops, LENLS, JURISIN, AMBN, ISS, Tokyo, Japan, November 18-19, 2010,
Revised Selected Papers, LNCS, vol. 6797, pp. 3–15. Springer (2011), http://hal.
inria.fr/inria-00565744
5. Danlos, L., Rambow, O.: Discourse relations and propositional attitudes. Con-
straint in Discourse (CID) (2011)
Discourse Structure of Speech and Attitude Reports 179
6. Hunter, J., Asher, N., Reese, B., Denis, P.: Evidentiality and intensionality: Two
uses of reportative constructions in discourse. In: Proceedings of the Workshop on
Constraints in Discourse. pp. 99–106. Maynooth: National University of Ireland
(2006)
7. Kamp, H., Reyle, U.: From Discourse to Logic: Introduction to Model-theoretic Se-
mantics of Natural Language, Formal Logic and Discourse Representation Theory,
Studies in Linguistics and Philosophy, vol. 42. Kluwer, Dordrecht (1993)
8. Kaplan, D.: Quantifying in. Synthese 19(1-2), 178–214 (1968)
9. Maier, E.: Presupposing acquaintance: a unified semantics for de dicto, de re
and de se belief reports. Linguistics and Philosophy 32(5) (2010), http://www.
springerlink.com/index/10.1007/s10988-010-9065-2
10. Vieu, L.: On the semantics of discourse relations. Constraint in Discourse (CID)
(2011)