Problem $4.(6pts=3+3)$ Use the logical equivalence laws and$/$or logical reasoning rules to prove that each

of the following arguments is valid.

notpvvq$r$

a$)$

svvnotq

notnott

$pt$

$not{p}^{{?}^{?}}r$notS

:$.$notq

$pvvq$

notpvvr

$\frac{\text{n}\text{o}\text{t}\text{q}}{\text{:}.r}$