shown in Fig. 1-5. Let A1, A2, and A3 denote the events that the switches 51, 52, and 53 are closed, respectively. Let Aab denote the event that there is a closed path between terminals a and b. Express Aab in terms of A1, A2, and A3 for each of the networks shown. 5 s1 2 5:1 S1 aD/.\"/Ib a o/ 53 30:!) {a}