Linguistics and Language Technologies

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Linguistics and Language Technologies

• Lori Levin
• 11-721 Grammars and Lexicons
• Fall Term 2003

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Linguistics

• Linguistics is a
• Cognitive Science
• Social Science
• Area of the Humanities
• Also, neuro-science, area of mathematics,
  computer science, etc.
• Primarily about the human mind and human
  communication behavior.

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Linguistics as a Cognitive Science

• Knowledge of language is not conscious knowledge.
  
• Like knowing how to walk without knowing which
  neurons and muscles are involved.
• What does knowledge of a language consist of?
• Sub-areas of linguistic knowledge
• Grammar of sentences (syntax), grammar of words
  (morphology), sentence meaning (semantics), word
  meaning (lexical semantics), language use in
  context (pragmatics and discourse analysis).
• Do human languages differ from each other in
  random ways, or are there common, universal
  properties?
• How are human languages different from
  mathematical languages, logical languages,
  programming languages, and animal communication
  systems?

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Linguistics as a Cognitive Science

• First language acquisition How do human babies
  learn something so complex so quickly with such
  imperfect input?
• Second language acquisition How do adults learn
  a second language, and why are they so bad at
  something that babies are so good at?
• Do adults learn languages better with immediate
  or delayed feedback on errors?
• Does explanation of foreign language grammar help
  adults learn the foreign language?
• Psycholinguistics How is human language
  processed in the brain and how is human language
  produced?
• When you hear the sentence He put his money in
  the bank? does your brain activate only the
  sense of bank that is related to money, or all
  of the senses of bank because they sound the
  same (e.g., river bank).
• Why do you have to do a double take to understand
  this sentence
• The cotton shirts are made of is soft.
• Neuro-linguistics What areas of the brain are
  activated during language processing? How do
  brain injuries affect language production and
  comprehension?

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Linguistics as a Social Science

• Historical Linguistics How do human languages
  change over time?
• Drift
• Corn used to mean all small grains, e.g, pepper
  corn, barley corn.
• What happened to the word britches?
• English f is systematically related to French
  p. What was the common sound that they both
  derived from in some ancient language?
• Foot/pied
• Father/pere
• Contact
• Languages in proximity to each other will
  influence each others vocabulary and grammar,
  even if the languages were previously unrelated.

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Language as a Social Science

• Sociolinguistics
• How do human languages vary with social factors
  such as
• Geography
• Age
• Ethnic group
• Sex
• Race
• Economic class
• In situations of language contact, what are the
  factors that determine whether there will be
  bilingualism or language loss?

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Language Technologies

• Computer based tools for processing human
  languages
• Speech recognition
• Speech synthesis
• Machine translation
• Human-machine dialogue systems
• Information Retrieval, Extraction, and
  Summarization
• Computer-assisted language learning

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Why should language technologists learn
linguistics?

• Audience participation.

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What does knowledge of a language consist of?

• Can he and Sam be the same person?
• He thinks that Sam is wrong.
• Sam expected to see him.
• Sam thinks that he is wrong.
• Sam believed him to be wrong.
• Sam expected Bill to see him.
• The person that he saw likes Sam.

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What does knowledge of a language consist of?

• Recognition of ambiguity
• I saw a man with a telescope.
• We sold her dog biscuits.
• Milk drinkers turn to powder.
• I saw a friend of Johns brother.
• Grandmother of nine makes hole in one.

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What does knowledge of a language consist of?

• Recognition of grammaticality.
• Many linguists (probably a majority) assume that
  people can distinguish strings of words that are
  sentences of their language from strings of words
  that are not sentences of their language.
• So imagine that you are a machine or a classifier
  that takes a sentence as input, and returns
  accept or reject as output.

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Grammaticality

• I gave back the car to him.
• I gave the car back to him.
• I gave the car to him back.
• I gave back him the car.
• I gave him back the car.
• I gave him the car back.

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Grammaticality

• I gave back the car to him.
• I gave the car back to him.
• I gave the car to him back.
• I gave back him the car.
• I gave him back the car.
• I gave him the car back.

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Grammaticality

• A string of words that you recognize as a
  sentence in your native language is grammatical.
• A string of words that you do not recognize as a
  sentence in your native language is
  ungrammatical.
• When you decide whether a sentence is grammatical
  or ungrammatical, this is called giving a
  grammaticality judgement.
• Ungrammatical sentences are preceded by an
  asterisk or star (). Sometimes they are called
  starred sentences.
• If native speakers cant decide whether the
  sentence is grammatical or ungrammatical, it is
  preceded by a combination of stars and question
  marks.

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Grammaticality Descriptive and Prescriptive
Linguistics

• Linguists describe what people say.
• Me and him went to the movies.
• Sam wants to boldly go where no one has gone
  before.
• Linguists do not prescribe what people should
  say.
• Language technologists dont get a say in the
  matter.
• If its in the input, you have to deal with it.
• When you give a grammaticality judgement, you are
  not supposed to judge whether the sentence is the
  most elegant or appropriate --- just whether it
  is a sentence of your language or not.

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Grammaticality

• Grammaticality is not completely determined by
  meaning
• Sentences 1 and 2 have similar meaning
• Bill saw Sam and Sue.
• Bill saw Sam with Sue.
• Sentence 2 can be transformed into a question by
  (1) changing Sue to Who, (2) moving it to
  the beginning of the sentence, and (3) making
  some changes to the verb.
• Who did Bill see Sam with?
• The same process applied to Sentence 1 does not
  result in a grammatical sentence.
• Who did Bill see Sam and?

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Grammaticality

• Sentences that are only possible in poetry are
  probably not grammatical
• To her we laurels bring.
• indirect-object subject direct-object verb
• We bring laurels to her.
• subject verb direct-object indirect-object

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Grammaticality

• Sentences that are only possible in poetry are
  probably not grammatical
• Bring we to our alma mater trust and honor due.
• verb subject indirect-object direct-object
• We bring trust and honor (that are) due to our
  alma mater.
• subject verb direct-object indirect-object

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Grammaticality

• Sentences that are understandable, but sound like
  mistakes are probably not grammatical.
• These are things that I dont know anyone who
  says.

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Grammaticality

• However, many types of sentences that are found
  in writing, or are restricted to special contexts
  are considered to be grammatical and even have
  names
• Locative Inversion In this village live many
  people.
• Topicalization Sam, I like.
• Heavy NP Shift I presented to the students many
  examples of strange and unusual constructions.
  (indirect object comes before direct object
  because the direct object is too long)

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Problems with Grammaticality

• Dialect differences
• The car needs washed.
• (The car needs to be washed.)
• We go to the movies a lot anymore.
• (We go to the movies a lot these days.)
• I gave it her.
• (I gave it to her.)
• It were me what told her.
• (It was me that told her.)
• Mine is bigger than what yours is.
• (Mine is bigger than yours is.)

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Problems with grammaticality

• What is the source of the problem?
• Colorless green ideas sleep furiously.
• Sleep ideas green furiously.

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Grammaticality in language technologies

• Real input (especially spoken input) is not
  always well-formed, so you should not build a
  program that accepts only grammatical sentences.
• Can we do away with grammar in language
  technologies?

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Grammaticality in Language Technologies

• You cannot extract the meaning of a sentence
  without processing the grammar
• Sue interviewed Sam.
• Sam interviewed Sue.
• LT output has to be comprehensible, and
  therefore, mostly grammatical
• Synthesized speech
• An automatically produced translation
• An automatically produced summary
• Error detection programs for computer-assisted
  language instruction or for word processing must
  distinguish grammatical from ungrammatical
  sentences.