nlpcontext-free-grammarchomsky-normal-form

Convert PCFG to CNF?

I have this rule in a grammar :

VP->Verb NP NP   [0.05]
VP->Verb NP PP   [0.1]

I want to convert this PCFG(Probabilistic Context Free grammar ) to CNF(Chomsky Normal Form)

To do that I know we can split the rule into two non-terminals 

VP->@V_N NP
VP->@V_N PP
@V_N->Verb NP

Which probability to set for each rule?

Thanks

Solution 
  • VP->@V_N NP     [0.05]
VP->@V_N PP     [0.1]
@V_N->Verb NP   [1.0]

    Because you need to get the same probability for the result by applying both the original and the converted set of rules.