 2. Assuming that all conflicts cancel each other out. This amounts to extending the above definition of a combined preference relation so that \(X\sim Y\) will hold in all cases of conflict, i.e. whenever there are \(\succcurlyeq_k\) and \(\succcurlyeq_m\) such that \(X \succ_k Y\) and \(Y \succ_m X\). Although usually not expressed in this way, this is the effect of applying efficiency as the sole criterion (e.g. Pareto efficiency as the sole criterion in a multi-person case). This method has the obvious disadvantage that it sometimes lets a small disadvantage in one dimension outweigh a large advantage in another dimension. 