(a) For each of the following formulas in FOL, give a suitable structure, a= (Uz, L), such that under this structure, (a.1) is False, and (a.2) and (a.3) are True: (a.1) vxvyvz((P(x,y) ^ P(y,z)) P(x,z)) (a.2) vxvy((P(x,y) ^ P(y,x))-x = y) (a.3) vxvy(P(a,y)- P(x,b))