Exercise 3. For a WFF

\\\\phi

, use induction to define

Count(\\\\phi ,pr)

, which returns the number of times proposition "pr" appears in

\\\\phi

, e.g.,

Count((pvvq),p)=Count((pvvq),q)=1

and

Count(((p->q)vvnotq),q)=2

. (5 marks)

Exercise 3. For a WFF , use induction to define Count (,pr), which returns the number of times proposition "pr" appears in , e.g., Count((pq),p)=Count((pq),q)=1 and Count(((pq)q),q)=2