自然语言的基本概念

• Human language is a system specifically constructed to convey meaning, and is not produced by a physical manifestation of any kind.
  • is a discrete / symbolic / categorical system.

• word ：is a signifer that maps to a signified (idea or thing).

  Tasks in NLP

  The goal of NLP: design algorithms to allow computers to “understand” natural language in order to perform some task.

• Example Tasks

  • Easy: Spell Checking, Keyword Search, Finding Synonyms
  • Medium: Parsing information from websites, documents, etc.
  • Hard: Machine Translation, Semantic Analysis (What is the meaning of query statement ?), Coreference, Question Answering.
• Represent Words
  • The first and arguably most important common denominator across all NLP tasks.
  • Earlier NLP: treats words as atomic symbols
  • Now: word vectors
    • need to have some notion of similarity and difference between words.
    • can encode this ability in the vector themselves. (distance measure such as Jaccard, Cosine, Euclidean, etc)