Discourse representation theory
Encyclopedia
Discourse Representation Theory (DRT) is a framework for exploring meaning under a formal semantics
approach. One of the main differences between DRT-style approaches and traditional Montagovian approaches is that DRT-style approaches include a level of abstract mental representations (discourse representation structures, DRS) within its formalism
, which gives it an intrinsic ability to handle meaning across sentence boundaries. DRT was created by Hans Kamp
in 1981. A very similar theory was developed independently by Irene Heim
in 1982, under the name of File Change Semantics (FCS).
Consider the sentence (1) below:
A farmer owns a donkey.
The DRS of (1) can be notated as (2) below:
[x,y: farmer(x), donkey(y), owns(x,y)]
What (2) says is that there are two discourse referents, x and y, and three discourse conditions farmer, donkey, and owns, such that the condition farmer holds of x, donkey holds of y, and owns holds of the pair x and y.
Informally, the DRS in (2) is true in a given model of evaluation if and only if there are entities in that model which satisfy the conditions. So, if a model contains two individuals, and one is a farmer, the other is a donkey, and the first owns the second, the DRS in (2) is true in that model.
Uttering subsequent sentences result in the existing DRS being updated.
He beats it.
Uttering (3) after (1) results in the DRS in (2) being updated as follows, in (4) (assuming a way to disambiguate which pronoun refers to which individual).
[x, y: farmer(x), donkey(y), own(x,y), beat(x,y)]
Successive utterances of sentences work in a similar way, although the process is somewhat more complicated for more complex sentences such as sentences containing negation
, and conditionals.
, only individual sentences are examined, but the context of a dialogue plays a role in meaning as well. For example, anaphoric
pronouns such as he and she rely upon previously introduced individual constants in order to have meaning. DRT uses variables for every individual constant in order to account for this problem. A discourse is represented in a discourse representation structure (DRS), a box with variables at the top and the sentences in the formal language
below in the order of the original discourse. Sub-DRS can be used for different types of sentences.
One of the major advantages of DRT is its ability to account for donkey sentence
s (Geach 1962) in a principled fashion:
Every farmer who owns a donkey beats it.
Sentence (5) can be paraphrased as follows: Every farmer who owns a donkey beats the donkey that he/she owns. Under a Montagovian approach, the indefinite a donkey, which is assumed to be inherently an existential quantifier, ends up becoming a universal quantifier, an unwelcome result because the change in quantificational force cannot be accounted for in any principled way.
DRT avoids this problem by assuming that indefinites introduce discourse referents which are stored in the mental representation and are accessible (or not, depending on the conditions) to expressions like pronouns and other anaphoric
elements. Furthermore, they are inherently non-quantificational, and pick up quantificational force depending upon the context.
On the other hand, genuine quantifiers (e.g., 'every professor') bear scope. An 'every-NP' triggers the introduction of a complex condition of the form K1 → K2, where K 1 and K 2 are sub-DRSs representing the restriction and the scope of the quantification respectively.
Unlike true quantifiers, indefinite NPs just contribute a new DR (together with some descriptive material in terms of conditions on the DR), which is placed in a larger structure. This larger structure can be the top-level DRS or some sub-DRS according to the sentence-internal environment of the analyzed NP -- in other words, a level which is accessible to an anaphor that comes later.
Formal semantics (linguistics)
In linguistics, formal semantics seeks to understand linguistic meaning by constructing precise mathematical models of the principles that speakers use to define relations between expressions in a natural language and the world which supports meaningful discourse.The mathematical tools used are the...
approach. One of the main differences between DRT-style approaches and traditional Montagovian approaches is that DRT-style approaches include a level of abstract mental representations (discourse representation structures, DRS) within its formalism
Formalism
The term formalism describes an emphasis on form over content or meaning in the arts, literature, or philosophy. A practitioner of formalism is called a formalist. A formalist, with respect to some discipline, holds that there is no transcendent meaning to that discipline other than the literal...
, which gives it an intrinsic ability to handle meaning across sentence boundaries. DRT was created by Hans Kamp
Hans Kamp
Johan Anthony Willem Kamp is a Dutch philosopher and linguist, responsible for introducing Discourse Representation Theory in 1981. Kamp received a Ph.D. in Philosophy from UCLA in 1968...
in 1981. A very similar theory was developed independently by Irene Heim
Irene Heim
Irene Roswitha Heim is a linguist and noted specialist in semantics. She was a professor at the University of Texas at Austin and UCLA before finally moving to the Massachusetts Institute of Technology in 1989, where she is Professor of Linguistics and Head of the Linguistics Section of the...
in 1982, under the name of File Change Semantics (FCS).
Discourse Representation Structures
In DRT are discourse representation structures (DRS) which represent a hearer's mental representation of a discourse as it unfolds over time. There are two critical components to a DRS:- A set of discourse referents representing entities which are under discussion.
- A set of DRS conditions representing information that has been given about discourse referents
Consider the sentence (1) below:
A farmer owns a donkey.
The DRS of (1) can be notated as (2) below:
[x,y: farmer(x), donkey(y), owns(x,y)]
What (2) says is that there are two discourse referents, x and y, and three discourse conditions farmer, donkey, and owns, such that the condition farmer holds of x, donkey holds of y, and owns holds of the pair x and y.
Informally, the DRS in (2) is true in a given model of evaluation if and only if there are entities in that model which satisfy the conditions. So, if a model contains two individuals, and one is a farmer, the other is a donkey, and the first owns the second, the DRS in (2) is true in that model.
Uttering subsequent sentences result in the existing DRS being updated.
He beats it.
Uttering (3) after (1) results in the DRS in (2) being updated as follows, in (4) (assuming a way to disambiguate which pronoun refers to which individual).
[x, y: farmer(x), donkey(y), own(x,y), beat(x,y)]
Successive utterances of sentences work in a similar way, although the process is somewhat more complicated for more complex sentences such as sentences containing negation
Negation
In logic and mathematics, negation, also called logical complement, is an operation on propositions, truth values, or semantic values more generally. Intuitively, the negation of a proposition is true when that proposition is false, and vice versa. In classical logic negation is normally identified...
, and conditionals.
Donkey anaphora
In one sense, DRT offers a variation of first-order predicate calculus -- its forms are pairs of first-order formulae and the free variables that occur in them. In traditional natural language semanticsSemantics
Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
, only individual sentences are examined, but the context of a dialogue plays a role in meaning as well. For example, anaphoric
Anaphora (linguistics)
In linguistics, anaphora is an instance of an expression referring to another. Usually, an anaphoric expression is represented by a pro-form or some other kind of deictic--for instance, a pronoun referring to its antecedent...
pronouns such as he and she rely upon previously introduced individual constants in order to have meaning. DRT uses variables for every individual constant in order to account for this problem. A discourse is represented in a discourse representation structure (DRS), a box with variables at the top and the sentences in the formal language
Formal language
A formal language is a set of words—that is, finite strings of letters, symbols, or tokens that are defined in the language. The set from which these letters are taken is the alphabet over which the language is defined. A formal language is often defined by means of a formal grammar...
below in the order of the original discourse. Sub-DRS can be used for different types of sentences.
One of the major advantages of DRT is its ability to account for donkey sentence
Donkey sentence
Donkey sentences are sentences that contain a certain type of anaphora, such as:* Every farmer who owns a donkey beats it.* Every police officer who arrested a murderer insulted him....
s (Geach 1962) in a principled fashion:
Every farmer who owns a donkey beats it.
Sentence (5) can be paraphrased as follows: Every farmer who owns a donkey beats the donkey that he/she owns. Under a Montagovian approach, the indefinite a donkey, which is assumed to be inherently an existential quantifier, ends up becoming a universal quantifier, an unwelcome result because the change in quantificational force cannot be accounted for in any principled way.
DRT avoids this problem by assuming that indefinites introduce discourse referents which are stored in the mental representation and are accessible (or not, depending on the conditions) to expressions like pronouns and other anaphoric
Anaphora (linguistics)
In linguistics, anaphora is an instance of an expression referring to another. Usually, an anaphoric expression is represented by a pro-form or some other kind of deictic--for instance, a pronoun referring to its antecedent...
elements. Furthermore, they are inherently non-quantificational, and pick up quantificational force depending upon the context.
On the other hand, genuine quantifiers (e.g., 'every professor') bear scope. An 'every-NP' triggers the introduction of a complex condition of the form K1 → K2, where K 1 and K 2 are sub-DRSs representing the restriction and the scope of the quantification respectively.
Unlike true quantifiers, indefinite NPs just contribute a new DR (together with some descriptive material in terms of conditions on the DR), which is placed in a larger structure. This larger structure can be the top-level DRS or some sub-DRS according to the sentence-internal environment of the analyzed NP -- in other words, a level which is accessible to an anaphor that comes later.