Paraphrases“Different expressions that convey the same meaning”< INLG 2006, Jul. 15th, 2006 >…… The software is available on the Web.
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Adj-to-V Paraphrasing in JapaneseApplication

Based on Lexical Constraints of Verbs!

Generation"

Atsushi Fujita
Naruaki Masuno
Satoshi Sato
Takehito Utsuro@ Nagoya Univ.
@ IBM Eng. & Tech.
@ Nagoya Univ.
@ Univ. of Tsukuba"!

Text simplification !Carroll et al., 1999"!Inui et al., 2003"
Pre- and post-editing for MT !Shirai et al., 1995"

Recognition""

QA !Hermjakob et al., 2002"!Takahashi, 2005"
Multi-document summarization !Barzilay et al., 2003"
2Approaches to handle paraphrases

Phenomena we focus on

Collecting synonymous expressions

Adj-to-V paraphrasing in Japanesefrom thesauri, parallel/non-parallel corpus, Web, etc.
! Lexical paraphrases (‘‘burst into tears’’ #$‘‘cry’’)

be loose-Adj-Present screw-ACC to tighten-V-Past!

(I tightened a loose screw.)

to loosen-V-Attributive screw-ACC to tighten-V-Past

Describing transfer rules(I tightened a loosen(ed) screw.)transformational grammar, synchronous grammar, etc.
! Syntactic paraphrases (passivization, topicalization)!

A challenge to inter-categorial paraphrasing

Combining transfer rules and lexical resources!

Reasonable material for extending lexical semantics!

"

Lexical relation (LFs in MTT: e.g. v(attractive) = attract)! Lexical constrains (aspectual property, agentivity, etc.)! Compositional paraphrases (alternation, category-shifting)"!

Bridging gaps between different syntactic categories
Utilizing frameworks for verbs, at first3Issue

4

Distribution of verbal suffixesClosed example collection Cad-c

Add proper verbal suffixes to ensure equivalency
be loose-Adj-Present screw-ACC to tighten-V-Past!

(I tightened a loose screw.)!

to loosen-V-Attributive screw-ACC to tighten-V-Past(I tightened a loosen(ed) screw.)da (ta)!

be desirable-Adj-Present result-ACC to gain-V-Past

91 Adj tokens
148 candidate Vs
Choice points

to desire-V-Progressive-Past result-ACC to gain-V-Past(We obtained a desired result.)dei (tei)-ta

What sorts of suffixes are appended?
! What determines them?

!

!

ViVtru972tei-ru
re-ru

5

32

140

14

re-tei-ru

202ta

57

44

13tei-ta
re-ta

20

2

60

6

Majority

re-tei-ta

000ta" re- ruta and tei-ru

440ta and ru

1

1

0

non-paraphrasable

48

1335

"

5

# of Adj-V pairs
Total

Voice: re/!
" Aspect: tei/!
" Tense: ru/ta"(We obtained a desirable result.)

Verbal suffixes

6

Task

Method: verbal features

Determining verbal suffixes!

Verb generation %$Utilizing lexical constraints

Input!

!

Output"da (ta) (Attributive)

Verbal suffixes for the V!

7 linguistic tests derived from LCS (Table 2, p.43)!Kageyama, 1996"!Kato et al., 2005"!Takeuchi et al., 2006"" Transitive or intransitive (V )a
" Aspectual property (5 tests: V -V )b f
" Agentivity (1 test: V )gloose$#$loosen
Pair of Adj (source) and V (target)" Head of noun phrase modified by the Adj/V screw"

candidates are those in Table 1!

Examples of manual examination result
nozomu (to desire): Va: “yes (transitive)”, Vb: “yes”, Vc: “yes”,Vd: “no”, Ve: “progressive”, Vf: “no”, Vg: “yes”" wasureru (to forget): V : “yes (transitive)”, V : “no”, V : “yes”,abc
Vd: “no”, Ve: “perfective”, Vf: “yes”, Vg: “no”"

be loose-Adj-Present screw-ACC to tighten-V-Past(I tightened a loose screw.)

to loosen-V-Attributive screw-ACC to tighten-V-Past(I tightened a loosen(ed) screw.)da (ta)7

Method: handmade rule-set

8

Experimental results (Table 4)

The rule-set consists of 8 rules (Table 3, p.43)

Verbal suffixes

Each labels either of verbal suffixes (Table 1)! Conditioned with conjunction of feature-valueta!

re-ru

7 linguistic test results" Some clues are employed in addition"

N: Semantic class of the noun !NIJL, 2004"# e.g. neji (screw): material 1 (1.4151)! D: Affix pattern# e.g. yurui (be loose) # yurumu (to loosen): A_i-V_mu! C: Clause or not!

!

"

18/29
1/1

Vt

12/14

12/19

7/13

7/11

3/6

0/1

0/5

0/2

0/0

0/1

0/0

Vi

0/3

0/0

0/6

0/0

Vt

1/21/72/4

2/5

ta and tei-ru Vi

2/4

2/2

0/1

0/1

No rulefor 11 inputs

for 6 inputs

Total (RULE)

63/100 63/100 29/56
29/53&63%' &63%' &52%' &55%'

BL

57/100 57/148 24/56
24/83&57%' &39%' &43%' &29%'

10with a larger dataset
Explore lexical properties of adjectives and contextual clues! Re-design the task: features ($aspect ($suffixes!

To ensure equivalence in aspectual meaning
Aspectual and agentive properties are useful

Other types of inter-categorial paraphrasing
Predicative and adverbial usages of adjectives to verbs
V-to-Adj (reverse)! Adj-to-N, N-to-Adj, etc.
!

Majority of the test collection is explained (R, P=.52-.63)! (Beats ML and SLM (for our small data-set))
!

"

1/6!

As a case study of inter-categorial paraphrasing

Determining verbal suffixes in Adj-to-V paraphrasing
"

18/18

3/3

Further experiments on Adj-to-V paraphrasing

Adj-to-V paraphrasing
"

42/63

3/13

Observations
Necessary conditions
for Vi+“ta” and “re-ru”
are covered
But those rules do notgive sufficientconditions
Others are not wellanalyzed yetFuture work

What we do:!

42/44

3/7

9Conclusion

ViVtVitei-ru

Otherwise non-paraphrasable

Cad-oVtru!

Cad-c

Recall Precision Recall Precision!

(Over-generation & SLM-based filtering work well)Re-formalization as a problem of lexical choice!
11

In what condition, V is preferable to Adj, Vi is to Vt
12