For problems 1-4, if L is a CFL then give a context-free grammar or NDPA that recognizes the language; otherwise, use the pumping lemma or closure properties to prove L is not a CFL. Is the language L_1 = {a^n b^m: n = 2^m} context-free? Is the language L_2 = {a^n b^j a^j b^n: n greaterthanorequalto 0, j greaterthanorequalto 0} context-free? Is the language L_3 = {a^n b^n c^j: n lessthanorequalto j} context-free? Is the language L_4 = {w: w element {a, b, c}* and n_a(w)