Extracting relationships

There are a number of techniques available to extract relationships. These can be grouped as follows:

  • Hand-built patterns
  • Supervised methods
  • Semi-supervised or unsupervised methods
    • Bootstrapping methods
    • Distant supervision methods
    • Unsupervised methods

Hand-built models are used when we have no training data. This can occur with new business domains or entirely new types of projects. These often require the use of rules. A rule might be:

"If the word "actor" or "actress" is used and not the word "movie" or "commercial", then the text should be classified as a play."

However, this approach takes a lot of effort and needs to be adjusted for the actual text in-hand.

If only a little training data is amiable, then the Naive Bayes classifier ...

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