Interpreting Dictionary Definitions

1
Interpreting Dictionary Definitions
Dan Tecuci May 2002
2
Problem Description

• Interpretation translating into one's own
  language
• Given
• Dictionary definitions of actions
• KB set of primives/components
• Argument structure
• Text generation
• Axioms
• Pre/post/during conditions
• User input
• Produce
• Representations of actions

3
Example

• Dictionary carry to move while supporting
• Challenges
• Identify what primitive components are referred
• Move, Support
• Deal with missing arguments
• An agent moves an object while supporting it
• Resolve references between them
• Agent1 moves object2 while Agent1 supports
  object2
• Identify deep semantic relations among them
• There are two subevents of Carry, one in which
  Agent1 moves object2 and one in which Agent1
  supports object2 so that object2 cannot fall, and
  they happen in parallel

4
What Is the Goal?

• Acquire different kinds of knowledge
• Taxonomic
• Semantics of actions
• Argument structure
• In order to
• Accelerate knowledge acquisition
• Execute actions
• Talk about them
• Understand when someone talks about them

5
Knowledge of Argument Structure

• What arguments does the verb have and where they
  surface (position)
• Multiple ways in which an argument can surface.
  
• E.G.
• Voa -gt carry something somewhere.
• The reverse of text-gen

6
Motivation

• Why this task
• Fast, automatic knowledge acquisition
• Language understanding and generation
• Available source of knowledge
• Why dictionaries
• Structured source of knowledge
• Taxonomic
• Argument structure
• Could be extended to full natural language
• Has been done before (manually)

7
Related Work - R. Amsler

• "The structure of MW dictionary" 80
• Analyses definitions based on kernels
  (superclasses)
• Main goal - build a taxonomy of motion verbs
• Other
• Procedure to analyse the argument structure of
  motion verbs (look at usage in other definitions
  and use componential analysis)
• Manual WSD, manual kernel identification,
  automatic taxonomy building

8
Related Work - C. Barrière

• From a children dictionary to a LKB
• Automatic translation of dictionary definitions
  into a knowledge representation formalism
• Specifics
• Uses an intermediary representation
• Only 1 sense of a word is analysed
• Children dictionary has usage examples

9
Related Work - C. Hastings

• Tries to acquire word (mainly verb) meaning from
  context (sentence)
• Uses LINK parser, semantic knowledge, terrorism
  domain
• KB has detailed info, fine-grained constraints
• Uses rules based on sentence structure to detect
  case-role assignment
• Syntactic/semantic knowledge is expressed in the
  same formalism (LINK)
• Algorithm
• Identify slot fillers
• Based on this, identify matching components

10
Related Work - FrameNet

• Mainly the same goal, but bottom-up
• Not based on composing a set of primitives
• Manually annotate sentences, automatically
  capture the organization of the annotation
  results
• Frame
• frame elements
• How FEs are realized in language
• Executable?

11
Dictionary Definitions

• Advantages
• Good source of taxonomic knowledge
• Follow a genus-differentia pattern
• Some dictionaries tend to define everything in
  terms of a basic vocabulary
• Disadvantages
• Definitions are elliptical
• Incomplete sentences (not easier to parse then
  NL)
• Leave blank argument positions that are nearly
  always filled in usage
• One definition does not provide enough info

12
What We Need

• What kind of knowledge do we need for such a
  task?
• Knowledge about primitive components
• Semantic - meaning
• Syntactic - argument structure
• How to determine when a concept is referenced?
• Knowledge about how to compose them and how this
  is reflected in language

13
Complex Actions

• What are complex actions?
• How to discover them?
• Dictionaries

14
Example - Steps

• Carry to move while supporting
• Steps
• Identify referenced concepts/components
• Identify their arguments
• How are the components assembled
• Resolve references
• Get knowledge about argument structure

15
Identifying components
Example move 1, support4 Move, Support
16
Identifying the arguments

• Arguments of Move, Support ?
• From
• definition
• Problem definitions omit args that are usu.
  present
• KB
• Minimal number of required args
• Arguments of Carry
• Suggested by
• syntax
• dictionary transitive/intransitive
• definitional patterns - Carry ISA Move
• How are they related ?

17
Assembling the components

• Meaning of the whole function of parts and the
  way they are composed
• Discover deep semantic relations among components
  referenced
• Prepositions clues
• Example
• while co-temporality or detraction
• by- by-means-of, agent, time, location
• Rules based on features of components
• How to test if a component is correct/coherent?
  (test-cases?)

18
Resolving co-references

• What object are co-referential?
• the agent of Move the agent of Support
• the object of Move the agent of Support
• How to do it?
• Heuristic assume everything maps unchanged
  unless there is reason to believe otherwise
• Matching
• Machine learning

19
KB

• Move
• 16 senses in WN 1.6
• 8 represented in CompLib tr. intr.
• What about argument structure?
• Multiple argument structure can correspond to a
  sense
• Argument structures
• Subj Move gt agent Subj
• Subj Move DObj gt agent Subj, object
  object

20
KB (cont.) Arg Struct for Move

• Full arg structure for Move
• agent moves object over distance using
  instrument along path from source to destination
• How to
• Acquire such knowledge?
• Express it?
• All possible trees
• Constraints (Subj always before Pred.)

21
Observations

• Verb definitions differ in level of generality
• More general - elliptical definitions
• Carry move while supporting
• Inherit more from primitive components
• More specific - more complete definitions
• Bioremediation treating waste or pollutants by
  the use of microorganisms (as bacteria) that can
  break down the undesirable substances
• Highly specialized versions of supers

22
What's next

• Focus on a subproblem (e.g. WSD)
• Get data (FrameNet?)
• Design an experiment
• Compare to existing methods

23
Research questions

• What dictionary to use? (WN?)
• How to represent arg struct knowledge?
• How would the special nature of the knowledge we
  have might help in this task?
• actions can be executed
• their results can be tested
• Does compositionality help?