 Turning to the short circuit, notice that we can use A*, B*, and E* as binary variables for whether the neurons a, b, and e do not fire. These variables take on the values 1 if their paired neuron doesn’t fire, and they take on the value 0 if it does. And, again, we can use C and D as variables for whether the neurons c and d fire; these non-asterisked variables take on the value 1 if their paired neuron does fire, and 0 if it doesn’t. With these conventions in place, we can then write down the following isomorphic system of equations for the neuron system of short circuit: