Is this set semi-decidable? A set of all  that M is a TM halts on all input strings w such that w <= q(M) where q(M) is the number of states in M
To show that $\overline{A}\notin RE$ you want to show that another language $B\notin RE$ is reducible to it.

First, the complement of $A$ is the set of all $\left&lt; M \right&gt;$, where $M$ is a Turing machine, and $\exists w$, $|w|&lt;q(M)$ s.t. $M$ doesn't halt on $w$.

Remember that you can add unreachable states to a Turing machine, therefore increasing $q(M)$. The next step would be picking a language who is known to be not decidable (e.g. the complementary of the halting language $\overline{H}$), and think of a reduction to $\overline{A}$.