We can first list all possible activation levels for each neuron in each of the two activation states.
By comparing the possible levels, those that are not acceptable for both states can be eliminated. Two neuron activation levels can already be determined, since there is a single level for each neuron appropriate for both states.
Eliminating the used levels from those available narrows the possible activation levels that can be assigned to the remaining neurons. Notice also that the –3 activation level can only be assigned to one possible neuron.
Continuing this process, the +2 and –2 activation levels are the last to be assigned.