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\title{Preferential Reference and Formalized Situated Meaning}

\author{Keith Devlin}

\date{EXTENDED ABSTRACT}

\begin{document}

\maketitle

\begin{abstract}
This paper presents a mathematically-based account of preferential reference (speaker's
choice of referring terms) and a formal definition of a mathematical notion of linguistic
meaning. The model of meaning is a relational model that captures a number of features of
meaning normally regarded as antithetical to a formally defined notion of meaning,
namely ad hocing, indexicality, and speaker's choice. It is shown that the model of
meaning defined can handle a wide variety of examples traditionally used to demonstrate
the shortcomings of mathematical notions of meaning.
\end{abstract}


\section{The existing situation}

In their book {\it Situations and Attitudes\/} \cite{BP}, published in 1983, Barwise and
Perry provide a mathematical definition of linguistic meaning grounded in situation
theory. More precisely, they provide two definitions, one intended to be a refinement of
the other. Both definitions attempt to capture meaning as a relation between situations.

The more basic of the two definitions defines the `meaning' of a linguistic expression
$\phi$ as a relation $\norm \phi\norm $ that links a situation $u$ in which $\phi$ is 
uttered to the object $e$ referred to or described by the utterance: $$u \norm \phi \norm
e.$$ The refinement takes the `meaning' of $\phi$ to be a four-place relation $$d,c \norm
\phi \norm \sigma,e$$ that links a discourse situation $d$ in which $\phi$ is uttered, a
speaker's connections function $c$, a setting $\sigma$ provided by other parts of the
utterance, and the object $e$ referred to or described.

\medskip

[Discussion of the relational theory of meaning.]

\medskip

\section{Objections to situation-semantic meaning}

There have been a number of objections raised to the model of linguistic meaning
described above. Some of them pertain---or at least appear to pertain---to any
mathematical notion of linguistic meaning. Others are directed more specifically at
situation semantics. It is not the purpose of this article to attempt a rebutal of all
objections, least of all the ones directed at mathematically-grounded semantic theories
in general. However, I believe that the new model of meaning I shall present here,
taken together with the modern (i.e. post 1990) conception of situation theory, can go a
long way to meeting many of the criticisms that have been made. What I shall do here is
address the linguistic issues that motivated the new model of meaning defined below.


\subsection*{The Winograd--Flores objection}

One of the objections to the original Barwise--Perry definition of meaning is its
assumption that words, phrases, and sentences have unique or {\it canonical\/}
meanings. This assumption is made, either openly or tacitly, by all current
mathematically-based semantic theories. ``But the assumption is wrong!'' cry the
objectors. ``Even the seemingly simplest of words acquire a great deal of their meaning
on any occasion of use from the circumstances surrounding that use.''

\medskip

[Brief discussion of inexicality.]

\medskip

The unwarranted assumption of fixed meanings was levelled against situation semantics by
Winograd in \cite{winograd1}, with essentially the same point being made about all
mathematical notions of meaning in general (or at least all the ones existing at the
time) in his book with Flores \cite{winflor}. In \cite{winflor}, Winograd and Flores
give the example of the word `water' to illustrate how the meaning of a word can depend
crucially on the context in which it is used. They ask us to consider the following
dialog (p.55):
\begin{quote}
{\small
A. Is there any water in the refrigerator?

B. Yes.

A. Where? I don't see it.

B. In the cells of the eggplant.
}
\end{quote}
Commenting on this brief imaginary exchange, Winograd and Flores observe that (p.56)
\begin{quote}
{\small In making the statement, ``There's some water in the refrigerator,'' a person
is not stating an objective fact. Every speech act occurs in a context, with a
background shared by speaker and hearer. The ``felicity conditions'' depend on mutual
knowledge and intentions.}
\end{quote}
Assuming that A was asking if there was a jug of drinking water in the refrigerator, then
B's response was ``infelicitous,'' to use the term Winograd and Flores used (after
Grice). If we take the word `water' to {\it mean\/} the liquid whose molecular structure
is H$_2$O and the word `in' to mean physically present in, then B's reply is accurate. If
we take the word `water' to {\it mean\/} the stuff that people drink, in drinkable form,
and `in' to mean present in a form accessible to drinking, then B's reply is wrong.

There is, say Winograd and Flores, no single, unique meaning for the word `water'. It
all depends on the circumstances under which the word is used. They present a number of
further possible replies by B to emphasize this point (pp.55--56):

\medskip

{\small
\begin{enumerate}
\item B. Yes, condensed on the bottom of the cooling coils.
\item B. There's no water in the refrigerator, but there's some lemonade.
\item B. Yes, there's a bottle of water in the refrigerator, with a little lemon in it
to cover up the taste of rust from the pipes.
\end{enumerate}}

\medskip

Response 1 might be appropriate if A were checking for sources of humidity that ruined
some photographic plates stored in the refrigerator. The difference between the
feliicity and infelicity of 2 and 3 depends on whether the presence of lemon in the
water disqualifies it from being classified as `water'. As the authors observe (p.56):
\begin{quote}
{\small We cannot come up with a situation-independent definition of what qualifies as
water, since after any amount of fiddling with the definition, one can always some up
with a new context in which it is inadequate. In making the statement ``There's some
water in the refrigerator,'' a person is not stating an objective fact.}
\end{quote}

[Further examples.]


\subsection*{The Clark objection}

Of course, Winograd and Flores are by no means the only ones to raise the issues
discussed above, nor are they the first. The phrase `the Winograd--Flores objection'
used to title the last section is purely a convenience. Likewise the reference to Clark
in this section. Unlike Winograd, who comes from computer science, Clark is a cognitive
psychologist. Clark's views, as expressed in \cite{clark}, have much in common with those
of Winograd and Flores.

For the purposes of this paper, I am most concerned with Chapter~12 of \cite{clark},
titled {\it Words, the World, and Their Possibilities}. However, a great deal of Clark's
book concerns the issue of reference and the role played by context in making adequate
and appropriate reference, and it is possible to take the mathematical framework I
develop here and use it to provide a `mathematical' version of much of Clark's account.

\medskip

[Quote from Clark.]

\medskip

Clark examines the influences that lead a speaker to choose the particular words she
does and the process whereby the speaker and listener reach their `momentary agreement'
on what those spoken words `mean'. He adopts the `common ground' approach to
conversation, whereby the participants engage in a joint activity that is supported by a
common ground of mutual knowledge and which itself contributes to that common ground.

\medskip

[Discussion of some of Clark's examples.]

\medskip

\subsection*{The sociologists' objection}

According to sociologists, `meaning' is not something inherent in a word or phrase;
rather it is something that emerges when two or more people interact through language.
`Situated meaning' is the term used to refer to this notion of meaning. The
sociolinguist observes that language users have a rich repertoire of cooperative
practices that enable them to contribute to interaction and to understand the
significance of other people's contributions. They rely on their experience in a common
culture, on a shared knowledge of language, on communicative conventions, and on various
interpretive strategies, in order to reach what are known as `momentary agreements' on
how what is said is to be interpreted. Language has formal features (phonetic,
syntactic, even semantic) but these do not function alone; on any given instance of
communication the formal and the cultural aspects are complementary---each contributes
to the mutual understanding that emerges from the interaction. Speakers make use of
their knowledge of social structure in choosing the words they use, and listeners
utilize their knowledge of social structure in order to interpret, in the manner the
speaker intended, the juxtaposition of the words spoken.

In order to understand the actual choice of words a speaker makes, we have to be aware of
the entire lexical system the speaker has at her\footnote{For definiteness I assume a
female speaker and a male listener throughout the paper.} disposal. For example, suppose
you were having a conversation with your friend, who suddenly exclaims, ``There is an
animal behind you!'' You turn round and see a dog. Your initial reaction will be to ask
yourself why your friend did not say ``There is a dog behind you!'' Indeed, you will
probably look for some explanation as to why your friend used the term `an animal' when
the `appropriate' phrase was `a dog'. In this case, both terms serve to identify the
creature behind you, and both sentences inform you that the said creature is behind you.
But they are not at all equivalent. One sentence seems `right', the other causes you to
seek an explanation as to why your friend used it. In fact, there is a whole range of
terms that would accurately describe the creature behind you---`carnivor', `canine
animal', `creature covered in hair', `animal with a pointed nose', `animal that barks',
`Melissa's pet', etc. In different circumstances, any one of those terms might be `the
right one' to use. But in the circumstances described, only one of them `fits', namely
`a dog', and the conventions of communication oblige your friend to use that term. (This
would not be the case if the dog in question were known to both you and your friend as
`Rover'. Under those circumstances, your friend would be obliged to say ``Rover is
behind you.'') Of course, the obligation to use a particular term from a whole range of
terms having the same referent, being a social obligation, can be broken. But to do so
changes the nature of what is communicated.

For the sociologist, then, insofar as words and phrases have an inherent `meaning', it
involves the manner in which the word or phrase is used in actual conversation (or other
kinds of linguistic interaction), including the factors that make the choice of a
particular word or phrase `the right one' on any particular occasion of use.


\section{Sacks' framework}

One of the main proponents of the sociological approach to language outlined above was
Harvey Sacks. One article by Sacks in particular has greatly influenced the theory of
reference and meaning presented here, his celebrated 1972 paper {\it On the
Analyzability of Stories by Children\/} \cite{sacks}.

\medskip

[Discussion of Sacks' framework.]

\medskip

Sacks assumes references are made using {\it categories}. In situation-theoretic terms,
these are (or correspond to) certain kinds of {\it object-types}. The following two
categories (object-types) play a significant role in his analysis:
\begin{itemize}
\item $T_{\mbox{\scriptsize\it baby}} = [\para{p} \mid w \models
      \ll \mbox{\rm baby}, \para{p}, t_{now}, 1 \gg]$, \ the type of all babies,
\end{itemize} where \para{p} is a parameter for a person and $w$ is `the world'; and
\begin{itemize}
\item $T_{\mbox{\scriptsize\it mother}} = [\para{p} \mid w \models \ll \mbox{\rm
      mother}, \para{p}, t_{now}, 1 \gg]$, \ the type of all mothers.
\end{itemize} Then, under suitable conditions, the `baby' category can be used to refer
to a baby, the `mother' category to refer to a mother.

However, Sacks presents evidence to show that reference is usually made not by a category
on its own but by a category considered as a member of a ({\it membership\/}) {\it
categorization device}. He defines a categorization device to be a non-empty collection
of categories, together with rules of application. For example, the categorization device
`gender' consists of the two categories `male' and `female', together with the rule for
applying these categories to (say) human populations. In situation-theoretic terms,
categorization devices are types of types that have a certain structure. The following
two categorization devices play a role in Sacks' analysis: \begin{itemize}
\item $T_{\mbox{\scriptsize\it family}}$, \ a type of types consisting of types
      such as `baby', `mommy', `daddy', etc.;
\item $T_{\mbox{\scriptsize\it stage-of-life}}$, \ a type of types consisting of
      types such as `baby', `child', `adult', etc.
\end{itemize}

\medskip

[Discussion of Sacks' framework.]

\medskip

\section{Preferential reference}

Based on the Sacks article, we can formulate a number of socially-based reference rules
that explain, in part, why certain terms of reference are preferred over other,
seemingly equivalent terms---`seemingly equivalent' in the sense that, under the same
context of use, they make reference to the very same referent.

In situation-theoretic terms, the fundamental referring structure is a pair \ $(T_{\it
cat}, T_{\it dev})$ \ consisting of a category \ $T_{\it cat}$ \ and a device \ $T_{\it
dev}$ such that \ $T_{\it cat}:T_{\it dev}$ \ (i.e. such that the category is in the
device).

The adequacy of such structures to make reference is guaranteed by Sacks' Economy Rule:
\begin{quote}
(ER) A single category from any device can be referentially adequate.
\end{quote}

Such a reference structure captures some of the social (i.e. contextual) information
that serves to disambiguate otherwise ambiguous terms of reference.

\medskip

[Discussion of Sacks' framework.]

\medskip

I formulated above a speaker's counterpart of the consistency rule CR, which I will now
rename as the {\it First\/} Preferential Reference Rule:
\begin{quote}
(PRR1) If some population of persons is being categorized, and if a category from some
device has been used to categorize one member of the population, then that category, or
other categories of the same device, should preferentially be used to categorize
further members of the population.
\end{quote}

\medskip

[Discussion of Sacks' framework.]

\medskip

My proposed speaker's version of this maxim is the Third
Preferential Reference Rule:
\begin{quote}
(PRR2) If a category-bound activity is to be asserted to have been done by a member of
some category where, if that category is ambiguous (i.e. is a member of at least two
different devices)  but where, at least for one of those devices, the asserted activity is
category bound to the given category, then a preferential form of reference is to use the
category from the device to which it is bound.
\end{quote}
Since the activity of crying is category-bound to the category `baby' in the stage-of-life
device, this is the natural way to see and to describe the activity, whenever such a way
of seeing and describing is possible.


\medskip

[Discussion of Sacks' framework.]

\medskip

To summarize, I have proposed to represent (or model) the sociolinguistic structure
involved in referring by means of situation-theoretic structures of the form
\ $(T_{\it cat}, T_{\it dev})$, where \ $T_{\it dev}$ \ is a categorization-device and \
$T_{\it cat}$ \ is a category in that device. The actual word used to make reference is
associated with the category \ $T_{\it cat}$. The device \ $T_{\it dev}$ \ points to the
required `sense' of the word by capturing aspects of the context of possible use. When the
device \ $T_{\it dev}$ \ is fixed by the context, the speaker's choice of terms to refer
to a particular object is restricted to terms whose associated categories are in that
device---restricted in the sense that, should a speaker choose to use a term whose
category, $T_{\it ref}$ say, is not in the device  \ $T_{\it dev}$, then the listener
will most likely look for a reason for such an unexpected form of reference, which
amounts to searching for an alternative device \ $T_{\it alt}$ \ such that the pair \
$(T_{\it ref}, T_{\it alt})$ \ is a reference structure that is appropriate under those
circumstances of use.


\section{A new model of meaning}

According to the sociolinguists, to `know' the meaning of a word is to `know' the
conditions under which is may be appropriately used. To a good degree of approximation,
the two-type, category--device referring structures introduced above provide a model of
meaning that captures that view of meaning.

The (formal) {\it meaning\/} of a referring word (or other referring term) $\alpha$ will
be defined as a relation, denoted by $\norm \alpha \norm$, between pairs $(d,u)$ of
situations and pairs \ $(T_{\alpha}, T_{\it dev})$ \ of types. The situation $u$ is the
utterance of $\alpha$. The situation $d$ is the larger context in which the utterance
occurs. In the case where the utterance $u$ forms part of a conversation, and if the
`common ground' model of conversation is assumed, then $d$ will be the conversational
common ground at the time of $u$. In any event, the situation $u$ is be referred to
simply as the {\it utterance}, the situation $d$ as the {\it context}. The type
$T_{\alpha}$ is the category associated with the term $\alpha$, the category of those
entities that may be referred to by the term $\alpha$. The type $T_{\it dev}$ is a
categorization device determined by contextual features in $d$. The category $T_{\alpha}$
is a member of the device $T_{\it dev}$, that is to say, as types $$T_{\alpha}:T_{\it
dev}.$$ The type $T_{\it dev}$ is called the {\it outer type\/} and the connection
between $d$ and $T_{\it dev}$ is called the {\it outer link\/} of the meaning relation.
The type $T_{\alpha}$ is called the {\it inner type\/} and the connection between $u$ and
$T_{\alpha}$ the {\it inner link}.

In terms of the discussion of referring structures in the previous section, the {\it
meaning\/} of a referring term $\alpha$ links pairs of situations---the utterance plus
the context of utterance---with the appropriate referring structure.

Notice that since the two items written on the left of the relation $\norm \alpha \norm$
are situations (and not types), this notion is very definitely one of {\it situated\/}
meaning. The meaning $\norm \alpha \norm$ combines with a pair $(d,u)$ of actual
situations to produce a referring structure \ $(T_{\alpha}, T_{\it dev})$.

Since the two items written on the right of the meaning relation are types (and not
individuals, relations, or situations), this notion of meaning corresponds more to the
`abstract meaning' of situation semantics (see \cite{LI}), rather than the
`meaning-in-use', though my present approach is not strictly comparable to current
situation semantics.

In many cases, the utterance situation $u$ or the context situation $d$ will determine a
specific object $a$ such that the utterance $u$ of $\alpha$ makes reference to the object
$a$. In this case $a:T_{\alpha}$ \ and we say $a$ is the {\it interpretation\/} of
$\alpha$ in the utterance.

We oberved earlier that the range of words available to a speaker to make appropriate
reference to a particular individual (or to a particular activity or situation) is often
highly constrained by the surrounding circumstances. Let us see how well the model of
meaning just defined captures this feature of meaning.

Suppose that the speaker witnesses a scene in which a very young human, less than a year
old, is being cuddled by a woman in her late twenties. These circumstances establish a
context $d$ for the speaker to make an utterance reporting on what she observes. The
situation $d$ establishes an appropriate categorization device from which a suitable
referring category may be chosen, namely the `family' device $T_{\it family}$. Whatever
referring term the speaker chooses to refer to the small human, it will have to fit into
the framework described. That is, the speaker will have to utter (utterance $u$) a
referring term $\alpha$ such that the associated category
$T_{\alpha}$ is in the device  $T_{\it family}$. Of the many referring terms that would
refer to the small human, the one that best fits is `baby', and so the speaker is likely
to use that term, and likewise the speaker is likely to refer to the adult in the scene
by the term `mother'. Thus the speaker uses the following meanings (i.e. instances of
the meaning relation) in order to make the appropriate references:
$$d, u_1 \,\norm \mbox{\small BABY} \norm\, T_{\it baby}, T_{\it family}$$
$$d, u_2 \,\norm \mbox{\small MOTHER} \norm\, T_{\it mother}, T_{\it family}$$

Admittedly, attempting to describe the reporting process in a linear, almost algorithmic
fashion as above is somewhat misleading. However, the purpose of the present study is not
to provide a `how to' manual that instructs speakers how to make adequate and appropriate
reference. Rather the study starts from the observed fact that speakers do, regularly and
effortlessly, make adequate and appropriate reference, and the aim is to develop a model
of linguistic meaning that is rich enough to reflect, in particular, the fact that a
speaker's choice of referring terms is generally highly constrained. Aeronautical
engineers make extensive use of mathematical models of aircraft, but such models do not
fly, and meteorologists work with computer simulations of weather, but a computer
simulation of a storm does not make you wet. Analogously, the mathematical model of the
meaning of referring terms just presented may bear little resemblance to the {\it
process\/} whereby people actually do make reference, but that is not the point.

To continue with the same example, suppose that the scene witnessed by the speaker is the
same as before, but that this time it takes place in a hospital and the woman holding the
baby is wearing a white coat. Now the circumstances $d$ establish a different device,
namely the `hospital' device $T_{\it hospital}$, and the appropriate choices of terms to
refer to the woman are `doctor' or `nurse', since both of these are associated with
categories in the `hospital' device.

It should be stressed that preferential reference rules are just that: they express {\it
preferences}, not hard rules that have to be followed. On any given actual occasion, a
speaker will likely be subjected to a range of factors that influence her choice of
referring terms. The `clean cut' process outlined above is an artifact of this being a
study of reality, not reality itself. For example, in the hospital scenario, the small
human might be referred to by the term `baby', but another possibility would be
`patient'. The former term, `baby', comes from the devices `family', `stage of life', and
(assuming the hospital is a maternity hospital) `hospital', the latter term, `patient',
comes only from the device `hospital'. In particular, the speaker could use either of the
following meanings in order to refer to the baby:
$$d, u \,\norm \mbox{\small BABY} \norm\, T_{\it baby}, T_{\it family}$$
$$d, u \,\norm \mbox{\small BABY} \norm\, T_{\it baby}, T_{\it hospital}$$
The important feature of the new definition is that it indicates how the term used to
make reference has to {\it fit\/} the circumstances of its use. This is the principal
feature of meaning that is missing in existing mathematical models of meaning, and which
the present definition is designed to incorporate.

The Winograd--Flores `water' example is handled similarly. The category `water' (type
$T_{\it water}$) is a member of a number of devices, the `liquids' device, the
`drinkable liquids' device, the `chemical compounds' device, the `fire extinguishing
substances' device, etc. If the circumstances of utterance $d$ establish that the
speaker intends to refer to drinks, then the meaning of the word `water' will be
$$d, u \,\norm \mbox{\small WATER} \norm\, T_{\it water},
             T_{\mbox{\scriptsize\it drinkable liquids}}.$$
Suppose this is the meaning intended when the speaker, A, asks ``Is there any water in the
refrigerator?'' If the addressee, B, replies ``Yes, in the cells of the eggplant,'' then
B has assumed a different context $d'$ to give the meaning
$$d', u' \,\norm \mbox{\small WATER} \norm\, T_{\it water},
             T_{\mbox{\scriptsize\it chemical compounds}}.$$
Either by accident (misunderstanding) or design (the smart alec reply), the common
ground has been lost, with B assuming a different context from A. In this case, the word
is the same for both speakers, namely `water', and the `meaning' is the same, in the sense
of the entire relation that constitutes the meaning. What differ are the contexts that
establish, via the outer links, the appropriate instances of the meaning.

Turning to the Clark examples, these concern adjectives such as {\it red\/} or {\it a
few}. The relational notion of `meaning' for an adjectival term $\alpha$ is a relation
$$d, u \,\norm \alpha \norm\, T_{\alpha}, T_{\it item}$$ between pairs of situations $d,
u$ and pairs of types $T_{\alpha}$, $T_{\it item}$. The type $T_{\alpha}$ is the type of
all those things that can (under appropriate circumstances) be referred to as
``$\alpha$''. $T_{\it item}$ is the {\it item type\/}---the type of item being referred
to by the utterance $u$ of $\alpha$ under the circumstances $d$.

For example, in the case of `red',
$$T_{\it red} = [\para{x} \mid \exists \para{s} (\para{s} \models \ll \mbox{\rm red},
                   \para{x}, \para{t}, 1 \gg)].$$
The meaning of the word `red' then gives rise to a range of instances, among them:
$$\begin{array}{lcl}
\mbox{\it red hair} &:&
        d, u \,\norm \mbox{\small RED} \norm\, T_{\it red}, T_{\it hair}\\[.1in]
\mbox{\it red potato} &:&
        d, u \,\norm \mbox{\small RED} \norm\, T_{\it red}, T_{\it potatoes}\\[.1in]
\mbox{\it red cabbage} &:&
        d, u \,\norm \mbox{\small RED} \norm\, T_{\it red}, T_{\it cabbages}.
\end{array}$$
The outer-type, which is linked to the context $d$ by means of the outer link, determines
the appropriate interpretation of the word `red' by selecting the relevant subtype from
the type $T_{\it red}$.

As the above example illustrates, the relational definition of meaning is an intensional
one. There is no meaningful sense in which we may regard as a well-defined `set' the
collection of all situations in which the word `red' has been, will be, and may be
uttered. The meaning relation is not a set of 4-tuples, as would be the case if an
extensional view of relations were adopted. Rather, the definition provides an
intensional model of meaning. As such, is is intended to capture all non-figurative
possible uses of the word `red'. The actual sense of the word `red' on any particular
occasion depends on the circumstances of utterance, $d$, which determine the conceptual
context for the interpretation of the word by means of the outer link. (Figurative uses
of `red', such as `red herring', are discussed in the full paper.)


\section{Extending the model}

[Discussion of various extensions of the model.]

Comparing the new model of meaning with more traditional approaches to linguistic
communication, `naive semantics' (where the object of study is the `canonical
meaning' of words) results when the outer context $d$ is removed/ignored, and with it the
outer  type $T_{\it dev}$ or $T_{\it item}$ to which it is connected by the outer link:
$$\emptyset, u \,\norm \alpha \norm\, T_{\alpha}, \emptyset.$$
Asbtracting from $u$ to the type of all utterances of $\alpha$ produces the `abstract
meaning' of \cite{LI}; alternatively, leaving $u$ as a situation and replacing
$T_{\alpha}$ by an object of type $T_{\alpha}$ gives an instance of the `meaning-in-use'
of \cite{LI}. Thus the earlier notions of meaning in situation semantics arise as
derivations of the new notion defined here.

In closing, it is perhaps worth emphasizing that the new definition of meaning described
here may {\it look\/} superficially like the traditional relational definition of
meaning in situation semantics, but its nature is quite different. The traditional
definitions of meaning in situation semantics relate situations or types of situations to
objects or types of objects---that is, to objects or types of objects that are referred
to. The new definition relates situations---more precisely pairs of situations---to {\it
procedures for using language}. This represents a shift from the linguists' structural
approach to language to the social scientists' and psychologists' procedural approach. In
fact, the new definition was not arrived at by a process of modification of the
traditional situation semantic model of meaning, but by a close examination of the means
by which agents use language to make reference, as described in particular by Sacks. I
started out thinking that it would not be possible to capture enough of the complexity of
referential procedures in a model having the formal simplicity of the relational model of
meaning familiar in situation semantics. It thus came as a surprise when I realized that
it was possible to define a powerful model that is not significantly more complex in its
formal structure than the situation semantic model I was familiar with.


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\end{document}


