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Synonymies and conceptual vectors

Synonymies and conceptual vectors. NLPRS 2001 Mathieu Lafourcade, Violaine Prince LIRMM - France. Overwiew & Objectives. why synonymy? what : Conceptual vectors which synonymies ? for what : Use with lexical functions. Objectives. Evaluation

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Synonymies and conceptual vectors

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  1. Synonymies and conceptual vectors NLPRS 2001 Mathieu Lafourcade, Violaine Prince LIRMM - France

  2. Overwiew & Objectives why synonymy? what : Conceptual vectors which synonymies ? for what : Use with lexical functions

  3. Objectives • Evaluation • Semantic proxymity to possible contexts for lexical interchangeability • Relative synonymy • Elimination of transitivity punctum proximum • Subjective synonymy punctum remotum

  4. Conceptual vectorsvector 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}* 

  5. Conceptual vectors Thesaurus • H : thesaurus hierarchy — K concepts Thesaurus Larousse = 873 concepts • V(Ci) : <a1, …, ai, … , a873> aj = 1/ (2 ** Dum(H, i, j)) 1/16 1/16 1/4 1 1/4 1/4 1/64 1/64 4 2 6

  6. Conceptual vectors Conceptc4:peace peace conflict relations hiérarchical relations society The world, manhood

  7. Conceptual vectors Term “peace” c4:peace

  8. 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

  9. Angular distance DA(x, y) = acos(sim(x,y)) DA(x, y) = acos(x.y/|x||y|)) 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  < 0 DA(x+x, x+y) = DA(x, x+y)  DA(x, y)

  10. 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 …

  11. Relative synonymyAspectual or referential • Term polysemy • un personnel trié sur le volet (CHOISIR) • une liste triée par ordre alphabétique (ORDONNER) • le courrier est trié (REPARTIR) • A vector plays as an aspect (aka reference) • How can we exchange A & B in the context of C ?

  12. Relative synonymy • SynR(A, B, C) with C as a reference (ref) SynR(A, B, C) = DA(A+AC, B+BC) A+AC SynR(A, B, C) A B+BC C B

  13. Relative synonymyProperties • SynR(A, B, C) = SynR(B, A, C) • SynR(A, A, C) = DA(A  C, A  C) = 0 • SynR(A, B, 0) = DA(A, B • SynR(A, 0, C) = /2 • DA(charbon,nuit) = 0.9 • SynR(charbon, nuit, couleur) = 0.4 • SynR(charbon, nuit, noir) = 0.35

  14. Relative synonymyProperties • The relative synonymy is a measure which favors the closing in of 2 vectors: “black” a good punctum proximum for “coal” and “night” • Transitivity of the synonymy • SynR(coal, crow, black) = 0.18 • SynR(crow, night, black) = 0.5 • SynR(coal, night, black) = 0.35

  15. Absolute synonymy • SynA(A, B) a particular case with AB as ref SynA(A, B) = SynR (A, B, AB) A+A(AB) SynA(A, B) A AB B+B(AB) B

  16. Subjective synonymyPoint of view • Semantic discrimination scope • DA(tit, bird) = 0.7 • DA(sparrow, bird) = 0.48 • DA(tit, sparrow) = 0.23 • With which pow can we discriminate two given vectors? Closest “punctum remotum”

  17. Subjective synonymy • SynS(A, B, C) — C = point of view (pow) SynS(A, B, C) = D(A-AC, B-BC) A A-AC C B SynS(A, B, C) B-BC

  18. Subjective synonymy When DA(A, C)  /2 & DA(B, C)  /2 then SynS(A, B, C)  DA(A,B) SynS(A, B, 0) = DA(A, B) SynS(A, A, C) = 0 SynS(A, B, B) = DA(A-AB, 0) = /2 • DA(tit, crow) = 0.32 • SynS(tit, crow, zoology) = 0.54 • SynS(tit, crow, bird) = 1.07 • SynS(tit, crow, passerine) = 1.37

  19. Subjective synonymyProperties • non conservation of the concept hierarchy chain Concept chain • @the_world > @the_life > @animals > @birds • DA(tit, sparrow) = 0.23 • SynS(tit, sparrow, @the_life) = 0.75 • SynS(tit, sparrow, @the_world) = 0.5 • SynS(tit, sparrow, @animals) = 0.4 • SynS(tit, sparrow, @birds) = 0.9 Concepts horizon (at the lowest concept level)

  20. Subjective synonymyProperties • Polysemy: term vs concept • SynS(tit, sparrow, @birds) = 0.9 • SynS(tit, sparrow, bird) = 0.78 • Loosly correlated vectors as pow • SynS(tit, sparrow, @gold) = 0.7 • DA(tit, @gold) = 1.19 • DA(sparrow, @gold) = 1.15

  21. Objective synonymy A-A(AB) SynA(A, B) a particular case with AB as pow SynA(A, B) = SynA(A, B, AB) A AB B B-B(AB) SynA(A, B)

  22. Conclusion • Synonymy as enhancement of thethematic analysis • The conceptual vector models showsinterferencies • from polysemy : relative synonymy • from the complex relation btw concept and terms (bird vs @birds) • System in continuous learning • Evolving results • Hopefully converging

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