$5\mathrm{.}6$ A sequential circuit with two $D$ flip$-$flops A and $B,$ two inputs, $x$ and $y$; and one output $z$ is specified by the following next$-$state and output equations $($HDL$-$see Problem $5\mathrm{.}35)$:

$A(t+1)=x{y}^{\text{'}}+xB$

$B(t+1)=xA+x{B}^{\text{'}}$

$z=A$