Discrete Structure - Old Questions

19. A phrase structure grammar g is defined to be a 4-tuple (V, S, v₀ |→ ), where V=(v_o, w, a, b, c}, S={a, b, c}, v_o |→ aw, w |→ bbw, w |→ c. Derive a sentence of L(G), the language of this grammar.

OR

Prove that an undirected graph is a tree if and only if there is a unique simple path between any two of its vertices.