Parts of Speech

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Parts of Speech

• Grammars and Lexicons
• 11-721
• Fall Term, 2003

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Categories of WordsParts of Speech

• Noun
• Verb
• Adjective
• Adverb
• Preposition
• Determiner (Article)
• Modal ?

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Parts of Speech
Det Noun Modal Verb Adverb Adjective
Prep. Det Noun
This boy must seem incredibly stupid to
that girl.
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A note on scientific method

• Theories must be falsifiable.
• Results must be reproducible.

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Reproducible Results Chomsky, 1957

• The search for rigorous formulation in
  linguistics has a much more serious motivation
  than mere concern for logical niceties or the
  desire to purify well-established methods of
  linguistic analysis. Precisely constructed
  models for linguistic structure can play an
  important role, both negative and positive, in
  the process of discovery itself. By pushing a
  precise but inadequate formulation to an
  unacceptable conclusion, we can often expose the
  exact source of the inadequacy and, consequently,
  gain a deeper understanding of the linguistic
  data. More positively a formalized theory may
  automatically provide solutions for many problems
  other than those for which it was explicitly
  designed. Obscure and intuition-bound notions
  can neither lead to absurd conclusions nor
  provide new and correct ones, and hence they fail
  to be useful in two important respects.

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Notional Definitions of Parts of Speech(an
example of obscure and intuition-bound notions)

• Verbs denote actions
• Nouns denote entities
• Adjectives denote states
• Adverbs denote manner
• Prepositions denote location
• Determiners specify

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A Non-falsifiable Theory

• Theory noun denote entities
• Counter-example assassination is a noun that
  denotes an event
• Reply no, it denotes the idea of the event,
  which is an entity
• How do you tell the difference between an event
  and the idea of an event?
• Without precise definitions, this theory cannot
  be disproved.
• (In language technologies, imprecise definitions
  lead to poor intercoder reliability, which leads
  to poor training, etc.)

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A Falsifiable Theory

• Only prepositions can be modified by right
  meaning completely or directly.
• Supporting Examples
• Right up/down/in/on/across the street
• Right in the drawer
• Right down the stairs
• Right from school
• Right across the street
• He right despaired.
• She chose right this one.
• Counter-examples
• She looked at him right strangely.
• (Right modifies an adverb.)
• You look a right clown. (Oxford English
  Dictionary)
• (Right modifies a noun.)
• The government made a right mess of it. (Oxford
  English Dictionary)
• (Right modifies another noun.)
• The theory is falsified (if you like the
  counter-examples). It needs to be refined (maybe
  by specifying which dialects it is valid for).

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How do you decide the part of speech of a word?

• Distribution
• Morphology Prefixes, suffixes, and other changes
  to the structure of the word.

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Distribution of Parts of Speech

• Great ideas spread quickly.
• Interesting ideas spread quickly.
• Stupid ideas spread quickly.
• Colorless ideas spread quickly.
• Words of the same category have the same
  distribution. For example, adjectives can come
  before nouns.

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DiscussionDistribution of parts of speech

• Great ideas spread quickly.
• The ideas spread quickly.
• Great idea spread quickly.
• Do great and the have the same part of speech?
• Do idea and ideas have the same part of speech?

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Templates for testing parts of speech that work
most of the time

• noun can be a pain in the neck.
• Television can be a pain in the neck.
• Linguistics can be a pain in the neck.
• This can be a pain in the neck.
• Happy can be a pain in the neck.
• From can be a pain in the neck.
• The can be a pain in the neck.
• Breathe can be a pain in the neck.

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What is wrong with this sentence?

• Cat can be a pain in the neck.

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Templates for testing parts of speech that work
most of the time

• They/it can verb.
• They/it can stay/leave/die/cry.
• They/it can gorgeous/cute/trendy.
• They/it can from/to/in/off/on.
• They/it can door/bible/gold/camera.

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What is wrong here?

• They can handle.
• They can accommodate.
• They can harbor.

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Templates for testing parts of speech that work
most of the time

• Modal I be frank?
• Can I be frank?
• Must I be frank?
• Should I be frank?
• Need I be frank?

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Templates for testing parts of speech that work
most of the time

• Very adverb or adjective
• Very slow
• Very slowly
• Very badly
• Very happy

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Templates for testing parts of speech that work
most of the time

• He treats her adverb.
• He treats her well.
• He treats her arrogantly.
• He treats her nicely.
• He treats her nice.
• He treats her good.

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Templates for testing parts of speech that work
most of the time

• They are very adjective.
• They are very nice/gentlemanly/ladylike.
• They are very gentlemen/ladies/faxes.
• They are very starve/die.
• They are very to/at/on.
• They are very in.
• They are very off.

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Templates for testing parts of speech that work
most of the time

• Right preposition.
• Right is an intensifier.
• Right up/down/in/on/across the street
• Right down the stairs
• Right in the drawer
• Right from school
• Right across the street
• He right despaired.
• She chose right this one.

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What about these sentences?

• She looked at him right strangely. (dialect)
• She is right pretty. (dialect)
• You look a right clown. (Oxford English
  Dictionary)
• The government made a right mess of it. (Oxford
  English Dictionary)

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Templates for testing parts of speech that work
most of the time

• He wrote determiner other works.
• He wrote the/all/these/no/few/many other works.
• He wrote despair/be/have other works.
• He wrote student other works.
• ?He wrote successful other works.

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Words can have more than one part of speech

• He needs to see a doctor. (verb)
• Need there be a problem. (modal)
• I feel a need to explore my roots. (noun)

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Morphology

• The form of words
• Affixes Prefixes, suffixes, infixes
• Stem changes swim/swam
• More about morphology in a couple of weeks.

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Morphological properties of English nouns

• Count nouns
• Cup/cups
• Book/books
• Mass nouns
• Attention/?attentions
• Sand/?sands
• Water/?waters
• Coffee/?coffees

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Morphological Properties of English adjectives

• Monosyllabic (one syllable) adjectives
• Tall/taller/tallest
• Fast/faster/fastest
• Multi-syllabic adjectives
• Intelligent/more intelligent/most intelligent

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Morphological Properties of English Verbs
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Invariant words no prefixes or suffixes in
English

• Prepositions (in, on, at, about, across, beyond,
  etc.)
• Modals (may, might, can, could, must, shall,
  should, etc.)

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The Computational View

• Who cares if it is falsifiable? It just needs to
  be implementable.
• Non-falsifiable theories tend to be
  non-implementable.

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Importance to you

• When you are building a lexicon, you will decide
  on parts of speech for words by using template
  tests and morphological tests.

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Discussion

• Toy house
• Big house
• Hypothesis 1 Toy is an adjective in toy house.
  Toy house is just like big house.
• Hypothesis 2 Toy is a noun in toy house. Toy
  house is a compound noun.
• Relevant diagnostic tests
• Adjectives can be made comparative.
• Adjectives can be modified by very.
• Nouns can be made plural.

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Discussion

• He is like his brother.
• Hypothesis 1 Like is an adjective.
• Hypothesis 2 Like is a preposition.
• Relevant diagnostic tests
• Comparatives
• Very
• Right

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Part of Speech Tagging

• Input string of words
• Output string of words with a part of speech
  associated with each word.
• Example
• Thisdet boyN likesV thatdet girlN
• Use statistical or rule-based knowledge about
  distribution.
• Usually use a long list of parts of speech, e.g.,
  around 40.