Discourse Representation Theory (DRT) is a formalism proposed in the 1980s to address challenges in interpreting discourse, such as resolving anaphoric pronouns. DRT uses Discourse Representation Structures (DRS) which describe objects and properties in a discourse. A DRS contains discourse referents in its top part and conditions relating them in the bottom part. DRSs can be combined through subordination and accessibility criteria determine which referents can serve as antecedents for pronouns. DRT provides a way to represent donkey sentences by establishing links between referents introduced in relative clauses and pronouns.

1. Discourse Representation Theory
Presented by Mark Chang

2. Discourse Phenomena
● Discourse is a sequences of sentences.
● When we look at discourse, interesting
challenges arise.
● One of these challenges is interpreting
pronouns, such as he, she and it.

3. Anaphoric Pronouns
● A woman walks. She smokes.
Need to Expand the scope of the existential quantifier.

4. Donkey Sentences
● Every farmer that owns a donkey beats it.
Expand the quantifier scope
It seems that the sentence is correct,
However...

5. Donkey Sentences
● Every farmer that owns a donkey beats it.
farmer
donkey
pigown
own
pigfarmer
farmer
beat

6. Donkey Sentences
● Every farmer that owns a donkey beats it.
farmer
pigown Pigfarmer
beat
donkey
own
donkeyfarmer
beat
False
False
True
True
TrueFalse

7. Discourse Representation Theory
(DRT)
● A formalism proposed in the early 1980s by Hans Kamp
● The invention of DRT led to a shift from a static to a
dynamic view on natural language semantics.
● Instead of working with first-order formula syntax, works with
explicit semantic representations.
● Discourse Representation Structure (DRS) describes the
objects mentioned in a discourse and their properties.

8. A First Example of DRS
● A woman walks. She smokes.
discourse referent x, y, in
the top part of the box.
conditions upon these
discourse referents in the
lower part of the box.

9. Syntax of DRSs and
DRS-Conditions
● Structure of DRS
● DRS-conditions
DRS-conditions
discourse referents

10. Syntax of DRSs and
DRS-Conditions
● DRS-conditions

11. Subordination
● B subordinates B' if and only if

12. Accessibility
● B is accessible from B' if and only if
– B subordinates from B'
– B and B' denote the same DRS
● Accessibility is the criterion for the antecedent
of anaphoric pronoun.
● Actually, Many factors play a role in pronoun
resolution, such as prosodic and syntactic
information and common-sense knowledge

13. Discourse Structure and
Accessibility
● Mary ordered a milk shake,
John tasted it.
The discourse referent y is accessible for discourse referent v.
An anaphoric link between it and milk shake is allowed.

14. Discourse Structure and
Accessibility
● Mary did not ordered a milk shake.
John tasted it.
When we introduced negation, an anaphoric link is blocked.
Hence, y is not accessible for v

15. Donkey Sentences
● Every farmer that owns a donkey beats it.
Following the definition of accessibility, the discourse referent y
introduced by a donkey is available as antecedent.
A link is established by the DRS-condition z = y.

16. Reference
● Computational Semantics
– http://www.coli.uni-saarland.de/projects/milca/courses/c