Re: need help developin better sense for context free languages

Chris F Clark wrote:
....
But ask yourself this one, how about a^jb^jb^j? Is that a CFL or not?
Explain why. How about a^jb^kc^j, a^jbc^jc^j, or a^jb^jcb^j? If you
can answer those questions, you are likely to understand the principle
distinction. Note, if you really know your stuff, you should be able
to turn any of the above solvable problems into a grammar that
actually expresses the language "precisely"--the unsolvable ones won't
have a grammar (why not?).

I'm a bit confused by this paragraph. What do you mean by "the
unsolvable ones"?

a^jb^jb^j does have a formal grammar.

Patricia
.

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