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Aucun%20titre%20de%20diapositive

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Title: Aucun%20titre%20de%20diapositive


1
Guessing Hierarchies and Symbols for Word
Meanings through Hyperonyms and Conceptual Vectors
Mathieu Lafourcade LIRMM - France http//www.lir
mm.fr/lafourcade
2
Overwiew Objectives
  • lexical semantic representations
  • conceptual vector model (cvm)
  • autonomous learning by the system
  • from a given  semantic space  (ontology)
  • Constructing texonomies
  • Hierarchical - findind hyperonyms
  • Multiple inheritance - views
  • ambiguity as noise
  • towards self contained WSD annotations
  •  I made a deposit at the bank 
  • ?  I made a deposit at the bankltgmoneygt

3
Conceptual vectors vector space
  • An idea
  • Concept combination a vector
  • Idea space
  • vector space
  • A concept
  • an idea a vector V
  • with augmentation V neighboorhood
  • Meaning space
  • vector space v

?
4
2D view of  meaning space 
product
cat
5
Conceptual vectors Thesaurus
  • H thesaurus hierarchy K concepts
  • Thesaurus Larousse 873 concepts
  • V(Ci) lta1, , ai, , a873gt
  • aj 1/ (2 Dum(H, i, j))

1/4
1
1/4
1/4
1/16
1/16
1/64
1/64
2
6
4
6
Conceptual vectors Concept c4peace
peace
conflict relations
hierarchical relations
society
The world, manhood
7
Conceptual vectors Term peace
c4peace
8

exchange
profit
finance
9
Angular distance
  • DA(x, y) angle (x, y)
  • 0 ? DA(x, y) ? ?
  • if 0 then x y colinear same idea
  • if ?/2 then nothing in common
  • if ? then DA(x, -x) with -x anti-idea of x

x
x
?
y
10
Angular distance
  • DA(x, y) acos(sim(x,y))
  • DA(x, y) acos(x.y/xy))
  • DA(x, x) 0
  • DA(x, y) DA(y, x)
  • DA(x, y) DA(y, z) ? DA(x, z)
  • DA(0, 0) 0 and DA(x, 0) ?/2 by definition
  • DA(?x, ?y) DA(x, y) with ?? ? 0
  • DA(?x, ?y) ? - DA(x, y) with ?? lt 0
  • DA(xx, xy) DA(x, xy) ? DA(x, y)

11
Thematic distance
  • Examples
  • DA(tit, tit) 0
  • DA(tit, passerine) 0.4
  • DA(tit, bird) 0.7
  • DA(tit, train) 1.14
  • DA(tit, insect) 0.62

tit insectivorous passerine bird
12
Some vector operations
  • Addition ? Z X ? Y
  • zi xi yi vector Z is normalized
  • Term to term mult ? Z X ? Y
  • zi (xi yi)1/2
  • vector Z is not normalized
  • Weak contextualization ? Z X ? (X ? Y)
    ?(X,Y)
  • Z is X augmented by its mutual information with
    Y

13
2D view of weak contextualization
X
Y
14
Autonomous learning 1/2
  • set of known words K, set of unknow words U
  • revise a word w of K OR (try to) learn a word w
    of U
  • From the web for w ask for a def D
  • specific sites dicts, synonyms list, etc. ? def
    analysis
  • general sites google, etc. ? corpus analysis
  • for each word wd of D
  • if not in K then add wd to U AND add VO to V
  • otherwise get the vector of wd AND add V(wd) to
    V
  • compute the new vector of w from def(D) and V

98870 words for 400000 senses (vectors) learned
in 3 years
French
 ever  looping process
15
Autonomous learning 2/2
V
TXT
V
PH
V
N, GOV
V

ADJ,
V
insectivorous passerine bird
16
(No Transcript)
17
Hyperonyms identifications
  • Extraction
  • Try all terms
  • too costly and unproductive
  • Extract potential candidates
  • From definitions, cooccurence lists etc.
  • Ex Cand(emerald) precious stone, stone, beryl,
    gem,
  • Evaluation of cand (m) to meaning (m)
  • Contextualize ?(c,m) c ? (c ? m)
  • Retain c such as ?(c,m) is the closest to m
  • Loop extracting hyper helps identifying meanings

18
Pierre précieuse
Gemme/pierre précieuse
Gemme/bourgeon
Gemme/résine
v
v
v

béryl
closest vector
Émeraude/pierre précieuse
Émeraude/béryl
Émeraude/gemme
v
v
v
Pierre précieuse
Gemme/pierre précieuse
Gemme/bourgeon
Gemme/résine
v
v
v

béryl
Émeraude/pierre précieuse
Émeraude/béryl
Émeraude/gemme
v
v
v
19
Pierre précieuse
0.9
Gemme/pierre précieuse
Gemme/bourgeon
Gemme/résine
0.81

béryl
0.7
0.85
Émeraude/pierre précieuse
Émeraude/béryl
Émeraude/vert
Émeraude/couleur
Pierre précieuse

Couleur/matière
Couleur/sensation
0.9
Gemme/pierre précieuse

Vert/couleur des signaux
Vert/couleur
0.81
béryl
0.85
Émeraude/vert
Émeraude/béryl
20
Moyen de transport
artefact
hypo
aliment
animal
véhicule/Moyen de transport
véhicule/vecteur
nourriture
wagon
automobile
Cheval/moyen de transport
Viande/nourriture
Voiture/wagon
mammifère
hypo
Voiture/automobile
Cheval/viande
Cheval/mammifère
Cheval/unité de puissance
21
Last words
  • Switching of representation
  • From subsymbolic to symbolic
  • and vice-versa ? readabily of symbols of
    words
  • global and local test functions
  • for vector quality assessment
  • decision taking about number of meanings or
    views
  • detectors when combined to lexical functions
    (antonymy, etc.)
  • the basis for
  • self adjustement toward a vector space of
    constant density
  • wsd as a reduction of noise (in context or out of
    context)
  • unification of ontologies
  • self emergent structuration of terminology
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