Understanding the semantic relationships between terms is a fundamental task in natural language processing applications. While structured resources that can express those relationships in a formal way, such as ontologies, are still scarce, a large number of linguistic resources gathering dictionary definitions is becoming available, but understanding the semantic structure of natural language definitions is fundamental to make them useful in semantic interpretation tasks. Based on an analysis of a subset of WordNet’s glosses, we propose a set of semantic roles that compose the semantic structure of a dictionary definition, and show how they are related to the definition’s syntactic configuration, identifying patterns that can be used in the development of information extraction frameworks and semantic models.

1. NLP & Semantic Computing Group
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Categorization of Semantic Roles for
Dictionary Definitions
Vivian S. Silva
Siegfried Handschuh
André Freitas

2. NLP & Semantic Computing Group
Introduction
Understanding the semantic relationships between
terms is a fundamental task in NLP applications
Structured resources that can express
those relationships in a formal way,
such as ontologies, are scarce
A large number of linguistic resources
gathering dictionary definitions is
becoming available
Understanding the semantic structure of natural
language definitions is fundamental to make
them useful in semantic interpretation tasks
Our Proposal:
A set of semantic roles that compose the semantic structure of a
dictionary definition, and an analysis on how they are related to
the definition’s syntactic configuration.
but…

3. NLP & Semantic Computing Group
Semantic Roles for Lexical Definitions
Aristotle’s classic theory of definition introduced important
aspects such as the genus-differentia definition pattern and
the essential/non-essential property differentiation. Taking
those principles as starting point and analyzing a sample of 100 randomly chosen
WordNet’s definitions, we derived the following semantic roles for definitions:
origin
location
[role]
particle
accessory
determiner
accessory
quality
associated
fact
purpose
quality
modifier
event
location
event time
differentia
event
differentia
quality
supertype
definiendum
has particle
modified by
has component
characterizedby
has type
addsnon-essentialinfoto

4. NLP & Semantic Computing Group
Definition’s Semantic Roles in Action
• Some examples:
• lake_poets:
• refinement:
• redundancy:
• slender_salamander:
• genus_Salix:
• unstaple:

5. NLP & Semantic Computing Group
Identifying Semantic Roles in Definitions
• The definition’s syntactic structure can provide valuable
information for automatic SRL. A few examples:
ROOT
English poets at the beginning of the 19th century who lived were inspired by itandin the Lake District
NP
NP
NNJJ
PP SBAR
PP CC VP… …
… …
differentia
quality:
JJ to the
left of the
supertype
supertype:
rightmost
NN in the
leftmost
NP
event time:
PP containing
a DATE
named entity
event location:
PP containing a
LOCATION
named entity
differentia
event:
SBAR
associated
fact: VP
inside a
SBAR and
after a CC

6. NLP & Semantic Computing Group
Conclusions
• In this work we…
 Proposed a set of semantic roles that reflect
the most common structures of dictionary
definitions
 Compared the identified semantic patterns
with the definitions’ syntactic structure
• Pointing out the features that can serve as
input for automatic role labeling

7. NLP & Semantic Computing Group
N L P
Categorization of Semantic Roles for
Dictionary Definitions
Thanks!