23 Consider the switching networks shown in Figure 1. Let Ex denote the event that switch Sk is closed, k = 1, 2, 3, 4. Let EAR denote the event that...

Please answer the following question. The figure above is needed. Thank you.

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1.23 Consider the switching networks shown in Figure 1.17. Let Ex denote theevent that switch Sk is closed, k = 1, 2, 3, 4. Let EAR denote the event thatthere is a closed path between nodes A and B. Express EAR in terms of theEx for cach network.