My teacher has given me two bnf grammars:
A ::= 'd' | A 'e' A | A 'f' A
B ::= 'd' | B B 'e' | B B 'f'
and four strings to match with them:
I've figured out two of them, but the other two have me stumped. I don't want anyone to tell me the answers, but if someone could give me some hints as to where I'm going wrong it would be much appreciated.
Hmmm...
By induction, all matches must have an odd number of characters. So neither of the 4 character strings can be a hit...
Oh wait. I just noticed the 'Y' in the first rule. Do we know what that is? It could break my argument right open...