CS626-460: Language Technology for the Web/Natural Language Processing

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CS626-460 Language Technology for the
Web/Natural Language Processing

• Pushpak Bhattacharyya
• CSE Dept., IIT Bombay
• Topic More on semantic relations

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Metonymy

• Associated with Metaphors which are epitomes of
  semantics
• Oxford Advanced Learners Dictionary definition
  The use of a word or phrase to mean something
  different from the literal meaning
• Does it mean Careless Usage?!

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Insight from Sanskritic Tradition

• Power of a word
• Abhidha, Lakshana, Vyanjana
• Meaning of Hall
• The hall is packed (avidha)
• The hall burst into laughing (lakshana)
• The Hall is full (unsaid and so we cannot enter)
  (vyanjana)

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Metaphors in Indian Tradition

• upamana and upameya
• Former object being compared
• Latter object being compared with
• Puru was like a lion in the battle with
  Alexander (Puru upameya Lion upamana)

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Upamana, rupak, atishayokti

• upamana Explicit comparison
• Puru was like a lion in the battle with Alexander
• rupak Implicit comparison
• Puru was a lion in the battle with Alexander
• Atishayokti (exaggeration) upamana and upameya
  dropped
• Purus army fled. But the lion fought on.

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Modern study (1956 onwards, Richards et. al.)

• Three constituents of metaphor
• Vehicle (items used metaphorically)
• Tenor (the metaphorical meaning of the former)
• Ground (the basis for metaphorical extension)
• The foot of the mountain
• Vehicle foot
• Tenor lower portion
• Ground spatial parallel between the
  relationship between the foot to the human body
  and the lower portion of the mountain with the
  rest of the mountain

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Interaction of semantic fields(Haas)

• Core vs. peripheral semantic fields
• Interaction of two words in metonymic relation
  brings in new semantic fields with selective
  inclusion of features
• Leg of a table
• Does not stretch or move
• Does stand and support

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Lakoffs (1987) contribution

• Source Domain
• Target Domain
• Mapping Relations

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Mapping Relations ontological correspondences

• Anger is heat of fluid in container

Heat (i) Container (ii) Agitation of fluid (iii) Limit of resistence (iv) Explosion Anger Body Agitation of mind Limit of ability to suppress Loss of control

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Image Schemas

• Categories Container Contained
• Quantity
• More is up, less is down Outputs rose
  dramatically accidents rates were lower
• Linear scales and paths Ram is by far the best
  performer
• Time
• Stationary event we are coming to exam time
• Stationary observer weeks rush by
• Causation desperation drove her to exterme steps

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Patterns of Metonymy

• Container for contained
• The kettle boiled (water)
• Possessor for possessed/attribute
• Where are you parked? (car)
• Represented entity for representative
• The government will announce new targets
• Whole for part
• I am going fill up the car with petrol

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Patterns of Metonymy (contd)

• Part for whole
• I noticed several new faces in the class
• Place for institution
• Lalbaug witnessed the largest Ganapati
• Question Can you have part-part metonymy

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Purpose of Metonymy

• More idiomatic/natural way of expression
• More natural to say the kettle is boiling as
  opposed to the water in the kettle is boiling
• Economy
• Room 23 is answering (but not is asleep)
• Ease of access to referent
• He is in the phone book (but not on the back of
  my hand)
• Highlighting of associated relation
• The car in the front decided to turn right (but
  not to smoke a cigarette)

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Feature sharing not necessary

• In a restaurant
• Jalebii ko abhi dudh chaiye (no feature sharing)
• The elephant now want some coffee (feature
  sharing)

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Proverbs

• Describes a specific event or state of affairs
  which is applicable metaphorically to a range of
  events or states of affairs provided they have
  the same of sufficiently similar image-schematic
  structure

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Formalization of WN
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Formalization of WordNet

• Mathematical Formal Theory
• Based on Formal Concept Analysis
• Defines Semantic Relationships
• Theoretical Analysis of Relationships and
  dependencies among them

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Formal Concept Analysis

• Formal Context K (G,M,I)
• G Set of Formal Objects
• M Set of Formal Attributes
• I G M
• A pair (A,B) is a Formal Concept if,
• A ßB and B aA

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Example of Formal Concept
Young Old Female Male
Person
Adult X
Female Person X
Male Person X
Child X
Woman X X
Man X X

• A Adult, Woman, Man B Old
• Here (A,B) is a Formal Concept.

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WordNet as a Formal Context

• Denotative Context
• here D is Denotata concepts are
• Disambiguated Words
• WordNet is a Lexical Context
• here W are Disambiguated Words
• An equivalence relation SYN is defined on set W
  as,
• where syn(w) is Synset of w

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Relational Concept Analysis

• Relations between concepts, i.e.
• Quantifiers are used to define such
  relationships
• as follows
• Notations

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Meronymy

• Two disambiguated words are in Meronymy Relation
  if their denotative word concepts are in relation
  where m is meronymy relation among
  denotata i.e.
• Various combinations of quantifiers lead to
  different types of Meronymy Relations

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Types of Meronymy

• A child can be a member of tennis
  club, but not all children are members of tennis
  club, nor do all tennis clubs have children as
  members.
• All door-handles are part of
  doors, but not all doors have to have handles.
• All sandwitches consist of
  breads, but not all breads are parts of
  sandwitches.
• Each bird feather is part of the
  bird and all birds have feathers.

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Hyponymy and Synonymy

• A disambiguated word is a Hyponym of other word
  if the concept it denotes is subconcept of
  concept denoted by the other word.
• Two disambiguated words are called Synonyms if
  they denote the same concept.

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Inheritence of Relations

• This is inherited by hypernyms of part
  and whole.
• This is inherited by hypernyms of
  whole and hyponyms of part.
• This is inherited by hyponyms of
  whole and hypernyms of part.
• This is inherited by a particular
  pair hyponyms of both.