ØConsider the matrix Qv, whose entries are the measured QoS values r≥0 over links (i,j) whenever such a link exists, or otherwise have an initial value, e.g. +∞ for delay and variance or 0 for bandwidth. ØThe matrix Kv provides us with the ``best QoS value'' for every path between every pair of vertices (i,j). Ø The operator         between two QoS parameters depends on the QoS metric that is being considered and can be the addition (+) for delay and variance, the minimum (min) for bandwidth etc. The        is also an operator that depends on the specific QoS metric q, and selects the ``best value'' among the elements on which it operates, e.g. in case of the delay, loss or variance metric it will obtain the minimum value, while for bandwidth it will select the maximum value, for all paths going from i to j.