In the inference rule in figure 1 there are 2(r + 1) variables that can be bound to positions in w 1 , and as many that can be bound to positions in w 2 .
the side conditions imply m ij = m ij + |u ij |, for i ∈ {1, 2} and 0 ≤ j ≤ r, and therefore the number of free variables is only r + 1 for each component.