R(b)=0，T(b)=0

R(c)= 1，T(c)= 1

rule

When x=a or b, R(x)? T(x) = 0

At this time (R(x)? T(x))→？ Q(x) = 1

When x=c, R(x)? T(x) = 1

At this time (R(x)? T(x))→？ Q(x) = 1 if and only if? Q(x) = 1？ Q(x)=0

So what? x((R(x)？ T(x))→？ Q(x))？ Q(x)=0

According to the condition of 1, x(P(x)? Q(x))

Can you launch? x P(x)

So? x P(x) xP(x)