Hands on CYK Solutions: CNF Conversion

Hands on CYK Solutions: CNF Conversion

by Yichen Carolyn Wang -
Number of replies: 1
In the CYK hands on, when converting to CNF I see that there are two possible solutions presented

Is it necessary to introduce the new rules X, Y, Z, U? Or could we also simplify the rules as such:
S -> S PNP
S -> S NP
VP -> VP PNP
NP -> NP Adj
since S -> NP VP, VP -> V NP, NP -> Det AN are already defined? Or is there another reason that we create the extra rules that I'm not understanding?
In reply to Yichen Carolyn Wang

Re: Hands on CYK Solutions: CNF Conversion

by Jean-Cédric Chappelier -
No you cannot do that: this is not an equivalent grammar because now, for instance, you can combine many times the first two rules, leading, for instance to NP VP PNP PNP NP VP NP PNP PNP etc... which is not valid in the original grammar.