Let $L_{i}$ be the set of strings accepted by the finite-state automaton $A_{i}=\left(\mathcal{I}, \mathcal{S}_{i}, f_{i}, \mathcal{A}_{i}, \sigma_{i}\right), i=1,2 .$ Let
$$A=\left(\mathcal{I}, \mathcal{S}_{1} \times \mathcal{S}_{2}, f, \mathcal{A}, \sigma\right)$$
where
$$\begin{aligned}f\left(\left(S_{1}, S_{2}\right), x\right) &=\left(f_{1}\left(S_{1}, x\right), f_{2}\left(S_{2}, x\right)\right) \\\mathcal{A} &=\left\{\left(A_{1}, A_{2}\right) \mid A_{1} \in \mathcal{A}_{1} \text { or } A_{2} \in \mathcal{A}_{2}\right\} \\\sigma &=\left(\sigma_{1}, \sigma_{2}\right)\end{aligned}$$
Show that $\operatorname{Ac}(A)=L_{1} \cup L_{2}$.