$($a$)$ Construct the truth table for the following Boolean function

$f(x,y,z)=(x^{{?}^{?}}y)vv(x^{\text{'}}{?}^{{?}^{?}}{y}^{{?}^{?}}z)vv(x^{\text{'}}{?}^{{?}^{?}}{y}^{{?}^{?}}{z}^{\text{'}}).$

$($b$)$ Use a Karnaugh map to simplify the Boolean expression above.