BarcelonaParaphrasing

Discussion: Paraphrasing

Moderator: Francis Bond; Scribe: Michael Goodman

Objective

• Share information on what is being done
  • parse and generate
    • problems with unknown words --- can't generate from MRS
    • can use Erik's generation model (in batch mode)
  • monolingual translation

    • EnEn

      • mainly underspecification of => poss_rel => compound_or_prep

        • minutes of meeting/meeting's minutes/meeting minutes/minutes of meeting's

      • need to build a scoring model for the underspecified MRS

      • need a full MT model for transfer rules

    • What about lexical? meeting/transactions --- massively larger TFS or external rules?

    • can everything be done by underspecification?

• Applications
  • SMT training data
  • query expansion
  • normalization
  • relaxed input for MT
  • debugging
  • anything else?
• How do we acquire paraphrase rules?
• Discuss ways to make paraphrasing more robust
  • generation often freezes (host lisp running out of memory?)
  • generation debugging tools

Notes

Some existing discussions:

• Early discussions

• Paraphrasing Top page

Overview

Objective: see what others are doing

Work has been done with parse + generate paraphrasing

• Works for syntactic, sometimes lexical, alternations

Also have done work with a monolingual MT system (by Darren Appling)

• Would like to do everything with underspecification
  • Perhaps Tim's approach could work

How to acquire paraphrase rules?

• Look for alternations in parallel corpora?

Making paraphrasing more robust.

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Discussion

Lexical substitution:

• Tim: Wordnet has not worked well in the past
  • syntactic constraints surrounding words are important
    • cannot just swap words

Tim: Are you doing paraphrasing for SMT on both sides?

• Francis: Not yet, but Jacy may be capable now.

Bill: What's difference between parse+generate and monolingual translation?

• Francis: Parse+generate only paraphrases where there are no semantic differences.
  • Certain orderings are prohibited because of topicalization stati
  • Lexical substitution is limited to semantic hierarchies

Richard: Is there closure in the process, or can it be re-run?

• Francis: Some recursive rules could do this, but not really beneficial.

Contractions are useful (eg. gonna -> going to)

Dan: Allow informal output?

• Francis: only formal output.
  • some corrections have been used (eg. "go to the the bar" -> "go to the bar")

Francis: The user/evaluator doesn't need to be bilingual, and you only need one grammar to produce paraphrases.

Francis: An issue: don't have the perfect unknown word handling mechanism.

• eg. "I went to Barcelona and ate bacalao" (eg. don't have "bacalao")
  • Cannot generate from this.

Francis: Round trip efforts give a new perspective on your grammar.

Stephan: Can now get what is wanted (eg unknown words, normalization of preds, etc)

• But have to add stuff to MRS construction code.
• Would rather do lemmatization on the input.