Figure 2 The use of cases is a reuse of previous experiences in a new situation. If the new problem situation is exactly like the previous one (which is supposed to have beer successful) then the reuse is simple: Just copy the old solution. The general reuse principle for a selected case is shown in Fig. 2.3. It is rare be able to use a solution exactly as it is recorded. This happens if the new problem situation is not too different in essential aspects from the nearest neighbour selected from the case base. Then the recommendation is to adapt the recorded solution before reusing it to best suit the new problem. This can be done either manually or automatically. CBR presents formal adaptation methods, which we will introduce next.