How can I show that $\{a^ib^jc^k|i=0 \lor j=k\}$ is not regular?
I tried applying the pumping lemma but it does seem to have a pumping length of 1?
Alternatively there is the Myhill–Nerode theorem. Are $\{a^ib^j|i=0 \lor j\in\mathbb{N}\}$ infinite many equivalence classes?