Fig. 2From: A mixed-integer linear programming approach to the reduction of genome-scale metabolic networksIf in the first step of the pruning procedure the flux through reaction 1 is set to zero, reaction 1 is removable and reactions 2 and 3 are non-removable. If in the first step reaction 2 or 3 is set to zero, both of them would be removable and reaction 1 would be non-removable. The resulting subnetwork is then smaller than the first oneBack to article page