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Joint Parsing and Alignment with Weakly Synchronized Grammars. David Burkett, John Blitzer, & Dan Klein. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A A A A A A. Statistical MT Training Pipeline. }. 1) Align sentence pairs (GIZA++) - PowerPoint PPT Presentation
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Joint Parsing and Alignment with Weakly Synchronized Grammars
David Burkett, John Blitzer, & Dan Klein
Statistical MT Training Pipeline
1) Align sentence pairs (GIZA++)2) Parse English sentences (Berkeley parser) Parse Foreign sentences
3) Extract rules (Galley et al. 2006)
4) Tune discriminative parameters
在at
办公室office
里in
读了read
书book
read
the
book
in
the
office
} Joint model for (1) & (2)
Data Setting for Joint Models
( 中文 ; )English WSJ
.
.
.
(EN; )(EN; )
(EN; )
( 中文 ; )...
( 中文 ; )
Chinese CTBParallel, Aligned CTB
.
.
.
(EN, 中文 ; )(EN, 中文 ; )
(EN, 中文 ; )
Unlabeled parallel text
.
.
.
(EN; 中文 )(EN; 中文 )
(EN; 中文 )
Word alignment grids
在at
办公室office
里in
读了read
书book
read
the
book
in
the
office
Syntactic Correspondences
EN中文Build a model
Correspondence via Synchronous Grammars
Synchronous derivation
Synchronous Derivation
Weakly Synchronized Example
Weakly Synchronized Example
Separate PCFGs
Weakly Synchronized Example
ITG alignment
Weakly Synchronized Example
Points for synchronization, but not required
Correspondence Model & Feature Types
办公室office
Feature type 1: Word Alignment
EN 中文
PPPP
Feature type 3: Correspondence
Feature type 2: Monolingual Parser
ENPP
in the office
EN 中文EN 中文 EN 中文EN 中文EN 中文
[HBDK09]
Estimating
EN 中文 EN 中文
• Set to maximize the log-likelihood of the correct parses & alignments
EN EN 中文中文 EN 中文
EN 中文• normalizes to sum to 1
Computing
PP PP Correspondence features tie pieces together
EN 中文
EN 中文
Computing exactly is intractable
EN 中文 EN 中文
Individual , , have polynomial-time dynamic programming algorithms
Approximating : Mean Field
• Exploit tractability in individual models:
• Factored approximation: EN 中文
PPPP
1) Initialize separately
2) Iterate:
• Set to minimize EN 中文
EN 中文
Algorithm
Large scale inference
We can approximate in polynomial time, but . . .EN 中文
Sum over possible alignments is an algorithm.
But computers are fast, right?
• Medium-length sentences are 50 words long• Small translation data sets are 250,000 sentences• ~4 quadrillion operations (See for speedup details)[BBK10, HBDK09]
Quantitative Results: Parsing
Series178
81
84
87
90 Monolingual Joint
Quantitative Results: Parsing
Chinese parser78
81
84
87
90 Monolingual Joint
85.7%
83.6%
Quantitative Results: Parsing
Chinese parser English parser78
81
84
87
90 Monolingual Joint
81.2%
84.5%
Incorrect English PP Attachment
Corrected English PP Attachment
Quantitative Results: Translation
Word alignment65
69
73
77
81
85
89 HMM Discriminative ITG Joint
69.5%
85.0%
BLEU improvement from 29.4 to 30.6
79.5%
Better Translations with Bilingual Adaptation
ReferenceAt this point the cause of the plane collision is still unclear. The local caa will launch an investigation into this .
Baseline (GIZA++)The cause of planes is still not clear yet, local civil aviation department will investigate this .
目前 导致 飞机 相撞 的 原因 尚 不 清楚 , 当地 民航 部门 将 对此 展开 调查Cur-
rently cause plane crash DE reason yet not clear, localcivilaero-
nauticsbureau will toward open investi-
gations
Bilingual Adaptation ModelThe cause of plane collision remained unclear, local civil aviation departments will launch an investigation .
Thanks