Pluses and minuses must alternate, since the path will alternate between hemispheres.
To highlight the valence distribution, all components but the pluses and minuses have been removed from the diagram.
The -1 values encode the decision 'defect' and are referred to as minuses.
On the other hand, pairs give the opportunity for two minuses to be changed at one step.
When this edge is chosen, both minuses in the pair become pluses.
One minus indicates a residual of at least minus two, while two minuses indicate a residual less than minus four.
Whatever system is put in place will not be perfect and there will always be pluses and minuses.
It is intended that these minuses and pluses shall balance, and that we shall be able to anticipate the right amounts.
