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Tree Transducers in Machine Translation Andreas Maletti Universitt Stuttgart Institute for Natural Language Processing andreas.maletti@ims.uni-stuttgart.de Szeged November 29, 2011 Tree Transducers in MT A. Maletti 1 Machine


  1. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter was decided , and everything was put in place Output: f kAn Tree Transducers in MT A. Maletti 6 ·

  2. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter was decided , and everything was put in place Output: f kAn Tree Transducers in MT A. Maletti 6 ·

  3. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter was decided , and everything was put in place Output: f kAn Tree Transducers in MT A. Maletti 6 ·

  4. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter , and everything was put in place Output: f kAn An tm AlHsm Tree Transducers in MT A. Maletti 6 ·

  5. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter and everything was put in place Output: f kAn An tm AlHsm Tree Transducers in MT A. Maletti 6 ·

  6. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter everything was put in place Output: f kAn An tm AlHsm w Tree Transducers in MT A. Maletti 6 ·

  7. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter was put in place Output: f kAn An tm AlHsm w Tree Transducers in MT A. Maletti 6 ·

  8. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter was put in place Output: f kAn An tm AlHsm w Tree Transducers in MT A. Maletti 6 ·

  9. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: the matter in place Output: f kAn An tm AlHsm w wDEt Tree Transducers in MT A. Maletti 6 ·

  10. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: in place Output: f kAn An tm AlHsm w wDEt Al > mwr Tree Transducers in MT A. Maletti 6 ·

  11. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: place Output: f kAn An tm AlHsm w wDEt Al > mwr fy Tree Transducers in MT A. Maletti 6 ·

  12. Word-based system (FST) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: Output: f kAn An tm AlHsm w wDEt Al > mwr fy nSAb hA Tree Transducers in MT A. Maletti 6 ·

  13. Phrase-based machine translation Schema Machine Language model Input − → translation − → − → Output system Phrase-based systems Language Machine model Input − → Segmenter − → translation − → − → Output system Tree Transducers in MT A. Maletti 7 ·

  14. Phrase-based machine translation Schema Machine Language model Input − → translation − → − → Output system Phrase-based systems Language Machine model Input − → Segmenter − → translation − → − → Output system Tree Transducers in MT A. Maletti 7 ·

  15. Phrase-based system (FST+Perm) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: And then the matter was decided , and everything was put in place Output: Tree Transducers in MT A. Maletti 8 ·

  16. Phrase-based system (FST+Perm) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: And then 1 the matter 5 was decided 2 , and everything 3 was put 4 in place 6 Output: Tree Transducers in MT A. Maletti 8 ·

  17. Phrase-based system (FST+Perm) And then the matter was decided , and everything was put in place � ���� � � ���� � � �� � ��� � ������� � � � ��� �� �� � �� � � �� � w f tm wDEt fy kAn An AlHsm nSAb hA Al > mwr Derivation Input: And then 1 the matter 5 was decided 2 , and everything 3 was put 4 in place 6 Output: f kAn 1 An tm AlHsm 2 w 3 wDEt 4 Almwr 5 fy nSAb hA 6 Tree Transducers in MT A. Maletti 8 ·

  18. Machine translation (cont’d) Phrase-based systems Language Machine model Input − → Segmenter − → translation − → − → Output system Syntax-based systems Language Machine model Input − → Parser − → translation − → − → Output system Tree Transducers in MT A. Maletti 9 ·

  19. Machine translation (cont’d) Phrase-based systems Language Machine model Input − → Segmenter − → translation − → − → Output system Syntax-based systems Language Machine model Input − → Parser − → translation − → − → Output system Tree Transducers in MT A. Maletti 9 ·

  20. Parser S S CC S CC ADVP NP-SBJ-9 VP and NP-SBJ-1 VP And RB DT NN VBD VP NN VBD VP was everything was then the matter VBN NP-9 VBN NP-1 PP , put decided * IN NP in NN place And then the matter was decided , and everything was put in place (thanks to K EVIN K NIGHT for the data) Tree Transducers in MT A. Maletti 10 ·

  21. S S CC S CC ADVP NP-SBJ-9 VP and NP-SBJ-1 VP And RB DT NN VBD VP NN VBD VP was everything was then the matter VBN NP-9 VBN NP-1 PP , decided put * IN NP in NN place hA nSAb POSS AlHsm Almwr fy NN NP tm DET-NN wDEt DET-NN * PREP NP PV NP-SBJ PV NP-SBJ1 NP-OBJ1 PP w VP VP An S CONJ S kAn * SUB S f PV NP-SBJ SBAR CONJ VP S Tree Transducers in MT A. Maletti 11 ·

  22. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 12 ·

  23. Contents Machine Translation 1 Extended Top-down Tree Transducers 2 Multi Bottom-up Tree Transducers 3 Synchronous Tree-Adjoining Grammars 4 Tree Transducers in MT A. Maletti 13 ·

  24. Weight structure Definition Commutative semiring ( C , + , · , 0 , 1 ) if ( C , + , 0 ) and ( C , · , 1 ) commutative monoids · distributes over finite (incl. empty) sums Example B OOLEAN semiring ( { 0 , 1 } , max , min , 0 , 1 ) Semiring ( R ≥ 0 , + , · , 0 , 1 ) of probabilities Tropical semiring ( N ∪ {∞} , min , + , ∞ , 0 ) Any field, ring, etc. Most of the talk: B OOLEAN semiring Tree Transducers in MT A. Maletti 14 ·

  25. Weight structure Definition Commutative semiring ( C , + , · , 0 , 1 ) if ( C , + , 0 ) and ( C , · , 1 ) commutative monoids · distributes over finite (incl. empty) sums Example B OOLEAN semiring ( { 0 , 1 } , max , min , 0 , 1 ) Semiring ( R ≥ 0 , + , · , 0 , 1 ) of probabilities Tropical semiring ( N ∪ {∞} , min , + , ∞ , 0 ) Any field, ring, etc. Most of the talk: B OOLEAN semiring Tree Transducers in MT A. Maletti 14 ·

  26. Weight structure Definition Commutative semiring ( C , + , · , 0 , 1 ) if ( C , + , 0 ) and ( C , · , 1 ) commutative monoids · distributes over finite (incl. empty) sums Example B OOLEAN semiring ( { 0 , 1 } , max , min , 0 , 1 ) Semiring ( R ≥ 0 , + , · , 0 , 1 ) of probabilities Tropical semiring ( N ∪ {∞} , min , + , ∞ , 0 ) Any field, ring, etc. Most of the talk: B OOLEAN semiring Tree Transducers in MT A. Maletti 14 ·

  27. Syntax Definition (A RNOLD , D AUCHET 1976, G RAEHL , K NIGHT 2004) Extended top-down tree transducer (XTOP) M = ( Q , Σ , ∆ , I , R ) with finitely many rules q ∆ → Σ q ′ ( x i ) . . . p ( x j ) . . . x 1 x k q , q ′ , p ∈ Q are states i , j ∈ { 1 , . . . , k } Tree Transducers in MT A. Maletti 15 ·

  28. Syntax (cont’d) Definition (R OUNDS 1970, T HATCHER 1970) Top-down tree transducer (TOP) if all rules q ∆ → σ . . . x 1 x k q ′ ( x i ) . . . p ( x j ) linear if no variable occurs twice in r for all rules l → r nondeleting if var ( l ) = var ( r ) for all rules l → r Tree Transducers in MT A. Maletti 16 ·

  29. Syntax (cont’d) Definition (R OUNDS 1970, T HATCHER 1970) Top-down tree transducer (TOP) if all rules q ∆ → σ . . . x 1 x k q ′ ( x i ) . . . p ( x j ) linear if no variable occurs twice in r for all rules l → r nondeleting if var ( l ) = var ( r ) for all rules l → r Tree Transducers in MT A. Maletti 16 ·

  30. Syntax (cont’d) Definition (R OUNDS 1970, T HATCHER 1970) Top-down tree transducer (TOP) if all rules q ∆ → σ . . . x 1 x k q ′ ( x i ) . . . p ( x j ) linear if no variable occurs twice in r for all rules l → r nondeleting if var ( l ) = var ( r ) for all rules l → r Tree Transducers in MT A. Maletti 16 ·

  31. Semantics Example States { q S , q V , q NP } of which only q S is initial q S S ′ q V q NP q V q NP → → → q V q NP q NP S VP VP x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 2 x 1 x 2 Derivation q S S ′ S ′ S ′ q V q NP q NP q V q NP q NP S ⇒ ⇒ ⇒ q V q NP q NP t 1 VP t 1 t 2 t 1 VP VP VP t 2 t 1 t 3 t 2 t 3 t 3 t 3 t 3 t 2 t 2 t 2 Tree Transducers in MT A. Maletti 17 ·

  32. Semantics (cont’d) Definition Computed transformation: τ M = { ( t , u ) ∈ T Σ × T ∆ | ∃ q ∈ I : q ( t ) ⇒ ∗ u } Tree Transducers in MT A. Maletti 18 ·

  33. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 19 ·

  34. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 19 ·

  35. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 19 ·

  36. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 19 ·

  37. Rule extraction S q CONJ VP S q S w PV NP-OBJ x 1 VP → NP-SBJ VP q x 1 twlY NP NML NNP VBD PP x 2 VBD x 2 DET-NN signed JJ NNP Voislav IN NP signed Yugoslav President for NNP AltwqyE Serbia SrbyA AltwqyE Alr } ys AlywgwslAfy fwyslAf En NN-PROP DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 20 ·

  38. Rule extraction S q CONJ VP S q S w PV NP-OBJ x 1 VP → NP-SBJ VP q x 1 twlY NP NML NNP VBD PP x 2 VBD x 2 DET-NN signed JJ NNP Voislav IN NP signed Yugoslav President for NNP AltwqyE Serbia q NP-SBJ SrbyA q NP NP-SBJ AltwqyE Alr } ys AlywgwslAfy fwyslAf → En NN-PROP x 1 x 1 NN-PROP NNP DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP fwyslAf Voislav w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 20 ·

  39. Rule extraction S q CONJ VP S q S w PV NP-OBJ x 1 VP → NP-SBJ VP q x 1 twlY NP NML NNP VBD PP x 2 VBD x 2 DET-NN signed JJ NNP Voislav IN NP signed Yugoslav President for NNP AltwqyE Serbia q NP-SBJ SrbyA q NP NP-SBJ AltwqyE Alr } ys AlywgwslAfy fwyslAf → En NN-PROP x 1 x 1 NN-PROP NNP DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP fwyslAf Voislav w PV NP-OBJ NP-SBJ CONJ VP q S NP NML → DET-NN DET-ADJ JJ NNP Alr } ys AlywgwslAfy Yugoslav President Tree Transducers in MT A. Maletti 20 ·

  40. Symmetry Original rule S q CONJ VP S w q PV NP-OBJ x 1 → VP q x 1 twlY NP x 2 VBD x 2 DET-NN signed AltwqyE Tree Transducers in MT A. Maletti 21 ·

  41. Symmetry Original rule Inverted rule q S q S CONJ VP S S w q CONJ VP PV NP-OBJ q VP x 1 → VP w q → q x 1 PV NP-OBJ twlY NP x 1 q x 2 VBD VBD q x 1 x 2 twlY NP DET-NN signed x 2 signed x 2 DET-NN AltwqyE AltwqyE Tree Transducers in MT A. Maletti 21 ·

  42. Symmetry Original rule Inverted rule q S q S CONJ VP S S w q CONJ VP PV NP-OBJ q VP x 1 → VP w q → q x 1 PV NP-OBJ twlY NP x 1 q x 2 VBD VBD q x 1 x 2 twlY NP DET-NN signed x 2 signed x 2 DET-NN AltwqyE AltwqyE Linear nondeleting XTT can be inverted Tree Transducers in MT A. Maletti 21 ·

  43. Preservation of regularity Schematics Language model Input − → Parser − → XTT − → − → Output Parse trees best parse tree n -best parses all parses Can all be represented by regular tree language Tree Transducers in MT A. Maletti 22 ·

  44. Preservation of regularity Schematics Input − → Parser − → Parse trees − → XTT − → . . . Parse trees best parse tree n -best parses all parses Can all be represented by regular tree language Tree Transducers in MT A. Maletti 22 ·

  45. Preservation of regularity Schematics Input − → Parser − → Parse trees − → XTT − → . . . Parse trees best parse tree n -best parses all parses Can all be represented by regular tree language Tree Transducers in MT A. Maletti 22 ·

  46. Preservation of regularity Schematics Input − → Parser − → Parse trees − → XTT − → . . . Parse trees best parse tree n -best parses all parses Can all be represented by regular tree language Tree Transducers in MT A. Maletti 22 ·

  47. Preservation of regularity (cont’d) Schematics Regular language − → XTT − → Regular language? Approach Input restriction Project to output Result Linear XTT preserve regularity Tree Transducers in MT A. Maletti 23 ·

  48. Preservation of regularity (cont’d) Schematics Regular language − → XTT − → Regular language? Approach Input restriction Project to output Result Linear XTT preserve regularity Tree Transducers in MT A. Maletti 23 ·

  49. Preservation of regularity (cont’d) Schematics Regular language − → XTT − → Regular language? Approach Input restriction Project to output Result Linear XTT preserve regularity Tree Transducers in MT A. Maletti 23 ·

  50. Composition Schematics Parse trees − → XTT − → . . . Example (Y AMADA , K NIGHT 2002) Reorder Insert words Translate words Tree Transducers in MT A. Maletti 24 ·

  51. Composition Schematics Stage 1 Stage 2 Stage 3 Parse trees − → XTT − → XTT − → XTT − → . . . Example (Y AMADA , K NIGHT 2002) Reorder Insert words Translate words Tree Transducers in MT A. Maletti 24 ·

  52. Composition Schematics Composed Parse trees − → XTT − → . . . Example (Y AMADA , K NIGHT 2002) Reorder Insert words Translate words Tree Transducers in MT A. Maletti 24 ·

  53. Composition (cont’d) Example (A RNOLD , D AUCHET 1982) σ t 1 σ σ δ t 2 σ t 1 δ t 2 t 1 δ t 3 σ t 2 t 3 δ t 4 t 3 ⇒ ∗ ⇒ ∗ δ t 4 σ t n − 4 t n − 3 δ t n − 2 t n − 3 σ t n − 3 σ t n − 2 t n − 1 t n t n − 1 t n t n − 2 σ t n − 1 t n Tree Transducers in MT A. Maletti 25 ·

  54. Summary E XPR S YM P RES P RES − 1 C OMP Model \ Criterion Linear nondeleting TOP ✗ ✗ ✓ ✓ ✓ Linear TOP ✗ ✗ ✓ ✓ ✗ Linear TOP R ✗ ✗ ✓ ✓ ✓ General TOP ✗ ✗ ✗ ✓ ✗ General TOP R ✓ ✗ ✗ ✓ ✗ Linear nondeleting XTOP ✓ ✓ ✓ ✓ ✗ Linear XTOP ✓ ✗ ✓ ✓ ✗ Linear XTOP R ✓ ✗ ✓ ✓ ✗ General XTOP ✓ ✗ ✗ ✓ ✗ General XTOP R ✓ ✗ ✗ ✓ ✗ Tree Transducers in MT A. Maletti 26 ·

  55. Summary E XPR S YM P RES P RES − 1 C OMP Model \ Criterion Linear nondeleting TOP ✗ ✗ ✓ ✓ ✓ Linear TOP ✗ ✗ ✓ ✓ ✗ Linear TOP R ✗ ✗ ✓ ✓ ✓ General TOP ✗ ✗ ✗ ✓ ✗ General TOP R ✓ ✗ ✗ ✓ ✗ Linear nondeleting XTOP ✓ ✓ ✓ ✓ ✗ Linear XTOP ✓ ✗ ✓ ✓ ✗ Linear XTOP R ✓ ✗ ✓ ✓ ✗ General XTOP ✓ ✗ ✗ ✓ ✗ General XTOP R ✓ ✗ ✗ ✓ ✗ Comp. closure ln-XTOP ✓ ✓ ✓ ✓ ✓ “composable” ln-XTOP ? ? ✓ ✓ ✓ Tree Transducers in MT A. Maletti 26 ·

  56. Implementation T IBURON [M AY , K NIGHT 2006] Implements XTOP (and tree automata; everything also weighted) Framework with command-line interface Optimized for machine translation Algorithms Application of XTOP to input tree/language Backward application of XTOP to output language Composition (for some XTOP) Example qNP.NP(DT(the) N(boy)) -> NP(N(atefl)) Tree Transducers in MT A. Maletti 27 ·

  57. Implementation T IBURON [M AY , K NIGHT 2006] Implements XTOP (and tree automata; everything also weighted) Framework with command-line interface Optimized for machine translation Algorithms Application of XTOP to input tree/language Backward application of XTOP to output language Composition (for some XTOP) Example qNP.NP(DT(the) N(boy)) -> NP(N(atefl)) Tree Transducers in MT A. Maletti 27 ·

  58. Implementation T IBURON [M AY , K NIGHT 2006] Implements XTOP (and tree automata; everything also weighted) Framework with command-line interface Optimized for machine translation Algorithms Application of XTOP to input tree/language Backward application of XTOP to output language Composition (for some XTOP) Example qNP.NP(DT(the) N(boy)) -> NP(N(atefl)) Tree Transducers in MT A. Maletti 27 ·

  59. Multi Bottom-up Tree Transducers S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA AltwqyE Alr } ys AlywgwslAfy fwyslAf En NN-PROP DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 28 ·

  60. Syntax Definition Extended multi bottom-up tree transducer (XMBOT) is M = ( Q , Σ , ∆ , F , R ) with finitely many rules q Σ → ∆ ∆ . . . q ′ p . . . . . . . . . x i x j x i ′ x j ′ . . . . . . x m x n x 1 x ℓ q ′ , p , q ∈ Q are now ranked states F ⊆ Q 1 final states Tree Transducers in MT A. Maletti 29 ·

  61. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) a b b e Tree Transducers in MT A. Maletti 30 ·

  62. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) a a b ⇒ b b q b e e e Tree Transducers in MT A. Maletti 30 ·

  63. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) a a a b b ⇒ ⇒ q b b q b b b e e e e e Tree Transducers in MT A. Maletti 30 ·

  64. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) a a a q a b b ⇒ ⇒ q ⇒ b b b b q b b b b b e e e e e e e Tree Transducers in MT A. Maletti 30 ·

  65. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) a a a q q a b b a a ⇒ ⇒ q ⇒ ⇒ b b b b b b q b b b b b b b e e e e e e e e e Tree Transducers in MT A. Maletti 30 ·

  66. Example States { f ( 1 ) , q ( 2 ) } with final state f and rules q a q b f q q q → → → e → q a a σ b b e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Example (Derivation) f a a a q σ q a b b a a a a ⇒ ⇒ ⇒ q ⇒ ⇒ b b b b b b b b q b b b b b b b b b e e e e e e e e e e e Tree Transducers in MT A. Maletti 30 ·

  67. Semantics Definition Computed transformation: τ M = { ( t , u ) ∈ T Σ × T ∆ | ∃ q ∈ F : t ⇒ ∗ q ( u ) } Tree Transducers in MT A. Maletti 31 ·

  68. Semantics Definition Computed transformation: τ M = { ( t , u ) ∈ T Σ × T ∆ | ∃ q ∈ F : t ⇒ ∗ q ( u ) } Example τ M = {� t , σ ( t , t ) � | t ∈ T Σ } a q q b f q q q → q → → e → a a σ b b x 1 x 2 e e x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 x 1 x 2 Tree Transducers in MT A. Maletti 31 ·

  69. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 32 ·

  70. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 32 ·

  71. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 32 ·

  72. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 32 ·

  73. S NP-SBJ VP NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 32 ·

  74. Rule extraction q S S → q p S CONJ VP x 1 x 2 x 3 NP-SBJ VP w x 2 x 3 x 1 NML NNP VBD PP signed JJ NNP Voislav IN NP Yugoslav President for NNP Serbia SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 33 ·

  75. Rule extraction q S S → q p S CONJ VP x 1 x 2 x 3 NP-SBJ VP w x 2 x 3 x 1 NML NNP VBD PP p signed JJ NNP Voislav IN NP VP PV NP-OBJ Yugoslav President for NNP q x 1 VBD → twlY NP Serbia x 1 signed DET-NN AltwqyE SrbyA Alr } ys AltwqyE En NN-PROP AlywgwslAfy fwyslAf DET-NN PREP NP DET-NN DET-ADJ NN-PROP twlY NP PP NP NP w PV NP-OBJ NP-SBJ CONJ VP S Tree Transducers in MT A. Maletti 33 ·

  76. One-symbol normal form Definition Rule in one-symbol normal form if it contains at most one symbol Tree Transducers in MT A. Maletti 34 ·

  77. One-symbol normal form Definition Rule in one-symbol normal form if it contains at most one symbol Example (E NGELFRIET , L ILIN , ∼ 2009) q b → q b b x 1 x 2 x 1 x 2 Tree Transducers in MT A. Maletti 34 ·

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