Using Wikipedia as a reference
for extracting semantic
information from a text
Andrea Prato
&
Marco Ronchetti
Università di Trento, Italy

Explicit Semantic Analysis
Gabrilovich
Markovich
2007

Throw away:
Stopwords
Fragment pages (<100 words)
Suffixes (stemming)

- Leukemia
- Severe combined
immunodeficiency
A sample (ESA) - Cancer
-Non-Hodgkin lymphoma
The development of T-cell leukaemia - AIDS
following the otherwise successful -ICD-10 Chapter II:
treatment of three patients with X-linked
severe combined immune deficiency (X-
Neoplasms;
SCID) in gene-therapy trials using -Chapter III: Diseases of the
haematopoietic stem cells has led to a re- blood and blood-forming
evaluation of this approach. Using a
mouse model for gene therapy of X-
organs, and certain
SCID, we find that the corrective disorders involving the
therapeutic gene IL2RG itself can act as immune mechanism
a contributor to the genesis of T-cell
lymphomas, with one-third of animals
- Bone marrow transplant
being affected. Gene-therapy trials for X- - Immunosuppressive drug
SCID, which have been based on the - Acute lymphoblastic
assumption that IL2RG is minimally
oncogenic, may therefore pose some risk
leukemia
to patients. - Multiple sclerosis.

1-Glossary_of_cue_sports_terms
A sample (ESA) 2-Swimming,
3-Ian_Thorpe.
4-NCAA_football_bowl_games,
Being so tightly packed, Venice doesn't 2005-06,
make an ideal place to come to practise
5-Swimming_machine,
your favourite sport, although you'll get a
6-American_football_strategy,
decent workout just walking around and
up and down bridges! If you've got any 7-Contract_bridge_glossary,
energy left for some extra exercise, try a 8-Olympic_Games,
spot of swimming (although pools are 9-Pingu_episodes_series_6,
rare) or even a jog. Venice is a bit of a 10-Venice.
desert for swimmers. You can go in off …
the Lido (if you're game) or at one of 15 - Corruption_in_Ghana
Venice's two public swimming pools …
(handily, they close in summer). 27 - Legislative_system_of_the
Lonely Planet Tourist Guide Peopleʼs_Republic_of_China.

Clustering

Wikipedia is hyperlinked

Swimming is clustered with Olympic Games

1-Glossary_of_cue_sports_terms
A sample (ESA) 2-Swimming,
3-Ian_Thorpe.
4-NCAA_football_bowl_games,
Being so tightly packed, Venice doesn't 2005-06,
make an ideal place to come to practise
5-Swimming_machine,
your favourite sport, although you'll get a
6-American_football_strategy,
decent workout just walking around and
up and down bridges! If you've got any 7-Contract_bridge_glossary,
energy left for some extra exercise, try a 8-Olympic_Games,
spot of swimming (although pools are 9-Pingu_episodes_series_6,
rare) or even a jog. Venice is a bit of a 10-Venice.
desert for swimmers. You can go in off …
the Lido (if you're game) or at one of 15 - Corruption_in_Ghana
Venice's two public swimming pools …
(handily, they close in summer). 27 - Legislative_system_of_the
Lonely Planet Tourist Guide Peopleʼs_Republic_of_China.

Throw away:
Large aggregators
 Category links
 Numbers
 Pages with more than (N=100) links

After clustering:
 only 3 clusters with cardinality larger than 1.
 The first cluster, with cardinality 21, was
automatically named Swimming.
 The second and the third both have cardinality
equal to 2, and they are named Training and
Venice-bucentaur.

Which one is
machine -generated?
Validation: Turing test
Classification
Text Classification
Classification

20 texts of length
Outcome ranging between 60
and 200 words. Texts
were collected from
various sources like
newspaper articles,
text books, random
web pages, MSN
Encarta.

Further improvements

Using only nouns
Using a POS Tagger to identify syntactic
roles in document to be classified
Keep only names (throw away the rest)
No degradation in the results!

Define Multiwords
 Lexical multiword identification approach:
 The following generative pattern is considered
((Adj∣Noun) + ∣((Adj∣Noun) ∗ (Noun Prep)?)
(Adj∣Noun)∗)Noun
+: One or more *: Zero or more ?: Zero or one ∣: Or
Validation: A candidate multiword is valid if there
is a Wikipedia entry related to it.

Text with multiwords:
Keep all nouns
Keep all adjectives that are part of a
multiword

Evaluation (human inspection of
results)
100 samples (50 technical, 50 generic)
Multiword improved significanty 7 (5 technical)
It improved marginally 13
It worsened marginally 6
Overall improvement: 10/% on technical text

Work in progress

Concept-mediated mapping
among documents
How similar are two docs?
Jaccard Index
Concept 1
Concept 2 Concept 2
Doc 1 Doc 3
Concept 3 Concept 3
Concept 4

Syllabi comparison

Inter
links

Mapping documents in different
languages
Deploying Wikipedia Interlinks
Jaccard Index
Concept 1
Concept 2 Concept 2
Doc 1 Doc 3
Concept 3 Concept 3
INTERLINKS Concept 4