A system for generating teaching initiatives in a computeraided language learning dialogue

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A system for generating teaching initiatives in a
computer-aided language learning dialogue

• Nanda Slabbers
• University of Twente
• Netherlands

Alistair Knott University of Otago New Zealand
June 9, 2005 Nancy
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Overview

• Introduction
• Existing work
• Goals
• Formal goals
• Substantive goal
• Te Kaitito
• Authoring mode
• Student mode
• Conclusion
• Questions

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Introduction

• A dialogue system has to create two different
  kinds of utterances
• Responses not much content selection
• Initiatives content selection is very important
• It is common to analysethe task of
  naturallanguage generationas a pipeline

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Existing Work

• Existing systems which focus on generating
  initiatives
• Used to accomplish a certain task.
• The difference is that a language learning
  dialogue doesnt have to look like a tutorial
  dialogue.
• Existing systems which focus on language
  learning
• Most initiatives come from the student.
• In such systems it is hard to learn by adapting
  utterances made by the teacher.

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Goals of the Generated Initiatives

• Content selection is the key process in
  generating initiatives.
• The process of content selection is typically
  defined in relation to two goals
• Formal goal creating a coherent text.
• Substantive goal achieving a certain effect on
  the hearer (in our case teaching the student a
  number of syntactic rules).

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Formal Goal - Possible Dialogue Acts

• Dialogue coherence cannot be defined at the level
  of dialogue acts.
• Therefore the system will only generate
  initiatives of the following dialogue acts
• Assertions
• Questions
• Genuine questions
• Teaching questions

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Formal Goal Topic Continuity

• We prefer initiatives which maintain the current
  topic of the dialogue
• Topic of utterance set of individuals and
  predicates it introduces
• Topic of dialogue combination of topics of last
  utterances
• Topic continuity overlap between topic of
  dialogue and topic of possible initiative

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Formal Goal Mix of Dialogue Acts

• First we want to decide which dialogue act will
  be taken
• Normally we decide this based on the topic
  continuity criterion.
• If there are initiatives which score equally in
  the topic continuity criterion, we prefer those
  which belong to a dialogue act which has not been
  recently used.

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Formal Goal Other Criteria

• After we have decided which dialogue act will be
  taken, we have to compare the possible
  initiatives belonging to that dialogue act.
• To achieve this we introduce three dialogue act
  specific criteria
• Assertions strategy
• Genuine questions order of creation
• Teaching questions complexity

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Substantive Goal Syntax Criterion

• Every utterance is parsed and syntactic
  representations are created.
• Using these representations a set of target
  syntactic rules can be created for each lesson.
• Each lesson teaches a different set of rules,
  beginning with simple rules and progressing to
  more complex rules.
• Using these rules initiatives which involve
  target rules can be preferred to other
  initiatives.

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Formal and Substantive Goals - Initiative
Generation Algorithm

• Our algorithm for generating initiatives has four
  steps
• Identify a set of possible topics.
• Generate a set of candidate initiatives.
• Create a shortlist of initiatives by scoring and
  ranking them based on the criteria.
• Assign a syntactic score and choose the
  initiative with the highest total score.

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Te Kaitito

• Te Kaitito is a bilingual dialogue system meant
  to teach the Maori language, but we will
  demonstrate the English version.
• The system supports two modes
• authoring mode to author new lessons.
• student mode to practice the lesson and learn
  the target rules.

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Authoring Mode

• In authoring mode the user is assumed to be a
  teacher.
• The teacher can author a character by
• Telling facts about itself You are John
• Entering question generation rules How is a
  person?
• At the end the facts and questions are stored in
  two separate knowledge bases.
• The set of target syntactic rules is created
  automatically.

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Authoring Mode Example Dialogue

• A Your name is John
• TK Okay
• A You are from Dunedin
• TK Okay
• A You are fine
• TK Okay

A How is a person? TK Okay A What is a persons
name? TK Okay A Where is a person from? TK Okay
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Student Mode Start of the Lesson

• Start of the dialogue
• Empty common ground
• Load knowledge bases and set of rules
• During the dialogue
• Dialogue consists of pairs of forward-looking and
  backward-looking dialogue acts.
• At transition relevant points the initiative is
  passed to the student, but he or she can concede
  the initiative to the system.

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Student Mode Example Dialogue

• S ltentergt
• TK How are you?
• S I am fine
• TK Okay
• S How are you?
• TK I am fine
• S ltentergt
• TK What is your name?
• S My name is Ann
• TK Okay
• S Who are you
• TK I am John

S ltentergt TK Where are you from? S I am from
Dunedin TK Okay S ltentergt TK I am also from
Dunedin S ltentergt TK Lets see if you
remember Who am I? S You are John TK Correct,
well done!
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Student mode End of the Lesson

• The previous dialogue continues until the system
  has evidence that all target rules have been
  assimilated by the student
• Each target syntactic rule has an assimilation
  score that is updated after an utterance.
• When the score reaches a certain boundary value
  the associated rule has been assimilated.
• When all rules reach the boundary value, the
  lesson ends successfully.
• When the student does not learn the rule, even
  when a correct application of the rule is shown,
  the lesson may end unsuccessfully.

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Conclusion

• Te Kaititos teaching dialogues are useful to
  practice conversational skills.
• The system only has a simple grammar, but since
  novice students also have a limited grammar, this
  is satisfactory.
• Adding initiatives is also beneficial
• When the student is lost, the dialogue can be
  continued by simply pressing the Enter key.
• The initiatives provide models of well-formed
  sentences, so the student can modify these and
  try them out.

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Questions

• Are there any questions?