$($a$)$ Given $\backslash$Sigma $=\{$x$7->$ R$,$y$7->$ R$,$z$7->$ R$\},$ implement $($using

forward substitution$)$ the following specification using a sequence

of $($nonparallel$)$ assignments.

$($x$,$ y$)=($xm$2+$ x $+$ my$,$ y $+$ mx$)$

$($b$)$ Use the alternation law to implement the following.

$\{$x$,$ y$,$ z$\}=\{$x$,$ y$,$ z$\}$ x$<=$ y$<=$ z$$