Temporal representation of a qualitative trajectory. Qualitative temporal representation of the behavior labeled QB4 in Fig. 4, namely of the variables x1 (a) and x2 (b). On the horizontal axis, the discrete sequence of symbolic instants at which the domains are sequentially traversed. On the vertical axis, the qualitative value space of each variable is reported. The qualitative values (∘) abstract all real values in the related open and closed intervals, whose width is highlighed by a dashed line. The stable states are denoted by ·. The continuous line connecting the qualitative values has been introduced to give a hint of the qualitative profile.