Search code examples
context-free-grammarregular-languageautomata

Is this a free context gramar language?


Is this a context free language?

{a^(2k) b^n c^n : k >= 0 ∧ 0 <= n <= m}
{a^(2k+1) b^n c^m :k >= 0 ∧ n >= m >= 0}


Solution

  • One way to prove a Language a Context-Free-Language is to write Context-Free-Grammar for the given language:(or either draw PDA)

    The language below:

    {a(2k) bn cm : k >= 0 and 0 <= n <= m} U {a(2k+1) bn cm : k >= 0 and n >= m >= 0}

    is Context Free Language

    I think you have made mistake in writing question as I commented to you question, I am doing for above grammar

    We can write Context-Free-Grammar for this Language:

    in Context-Free-Grammar productions of kind α --> β where α is a single variable.

    S --> S1 | S2

    S1 generates this part {a(2k) bn cm : k >= 0 and 0 <= n <= m} and S2 generates {a(2k+1) bn cm : k >= 0 and n >= m >= 0}

    S1 --> AB

    A --> Aaa | ^

    B --> bBc | ^

    B --> Bc

    And

    S2 --> AaC

    C --> bCc | ^

    C --> bC

    In grammar S is start Variable and {S, S1, S2, A, B, C} all are variable.
    So in above grammar every productions are in the form α --> β where α is a single variable hence given language is Context-Free-Language.

    Let me know if you have other doubt or if your language I misunderstood