Classification-and-Ranking Architecture Based on Intentions for Response Generation Systems
Existing response generation accounts only concern with generation of words into sentences, either by means of grammar or statistical distribution. While the resulting utterance may be inarguably sophisticated, the impact may be not as forceful. We believe that the design for response generation...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/5894/1/FSKTM_2008_1%20IR.pdf |
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| Summary: | Existing response generation accounts only concern with generation of words into
sentences, either by means of grammar or statistical distribution. While the resulting
utterance may be inarguably sophisticated, the impact may be not as forceful. We believe
that the design for response generation requires more than grammar rules or some
statistical distributions, but more intuitive in the sense that the response robustly satisfies
the intention of input utterance. At the same time the response must maintain coherence
and relevance, regardless of the surface presentation. This means that response generation
is constrained by the content of intentions, rather than the lexicons and grammar.
Statistical techniques, mainly the over generation-and-ranking architecture works well in
written language where sentence is the basic unit. However, in spoken language where
utterance is the basic unit, the disadvantage becomes critical as spoken language also
render intentions, hence short strings may be of equivalent impact. The bias towards shortstrings during ranking is the very limitation of this approach hence leading to our proposed
intention-based classification-and-ranking architecture.
In this architecture, response is deliberately chosen from dialogue corpus rather than
wholly generated, such that it allows short ungrammatical utterances as long as they satisfy
the intended meaning of input utterance. The architecture employs two basic components,
which is a Bayesian classifier to classify user utterances into response classes based on
their pragmatic interpretations, and an Entropic ranker that scores the candidate response
utterances according to the semantic content relevant to the user utterance. The high-level,
pragmatic knowledge in user utterances are used as features in Bayesian classification to
constrain response utterance according to their contextual contributions, therefore, guiding
our Maximum Entropy ranking process to find one single response utterance that is most
relevant to the input utterance.
The proposed architecture is tested on a mixed-initiative, transaction dialogue corpus of 64
conversations in theater information and reservation system. We measure the output of the
intention-based response generation based on coherence of the response against the input
utterance in the test set. We also tested the architecture on the second body of corpus in
emergency planning to warrant the portability of architecture to cross domains. In the
essence, intention-based response generation performs better as compared to surface
generation because features used in the architecture extend well into pragmatics, beyond
the linguistic forms and semantic interpretations. |
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