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The initial and final states in the HMM required when implementing the Viterbi algorithm for marking POS?

I do not quite understand how to use the initial and final states in the hidden Markov model. Are they necessary for the development and implementation of transition and radiation matrices?

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A start / end state is needed to model whether a tag can appear at the beginning or end of a sentence.

For example, if you had a five-word sentence and you looked at two tags

  • Det Noun Verb Detoun Doun
  • Det Noun Verb Det Adj

, Det- > Noun Det- > Adj . , Adj, , , . ,

  • START Det Noun Verb Det Noun END
  • START Det Noun Verb Det Adj END

P (END | Noun) P (END | Adj).

, START/END , . , :

Det Noun Verb
Det Noun Verb Det Noun


START Det Noun Verb END
START Det Noun Verb Det Noun END

, :

  • P (Det | START) = 2/2
  • P (END | Verb) = 1/2
  • P (END | Noun) = 1/3

, : P (START | START) = 1 P (END | END) = 1

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, . , , , , (), . , , / . .

, , , , , . . , , / .

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