Write a context free grammar for structure of a english sentence, where a pronoun is followed by a verb and verb is followed by determiner. Determiner is followed by noun and noun can be followed by noun. Statement can begin with noun or a proper noun. **following program is written for example sentence"I prefer a morning flight from New Delhi".

LEX FILE:

%{
#include "y.tab.h"
%}
%%
I {return pronoun};
prefer {return verb;}
a{return determiner;}
morning|flight {return noun;}
from {return preposition;}
NewDelhi {return propernoun;}
%%

YACC FILE:

%{
#include<stdio.h>
%}
%token noun pronoun propernoun determiner verb preposition
%%
S : NP VP {printf ("Sentence accepted");}
   ;
NP : pronoun
      | propernoun
      | determiner nominal
      ;
nominal : noun nominal
               | noun
               ;
VP : verb
      | verb NP
      | verb NP PP
      | verb PP
      ;
PP : preposition NP
      ;
%%

main()
{
yyparse();
}
yyerror(char * arg)
{
printf("invalid sentence");
}

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