 The second common motivation for the view that being a K-system is the mark of chaos is the idea that the shift from zero to positive KS-entropy marks the transition from a ‘regular’ to ‘chaotic’ behaviour. This may suggest that having positive KS-entropy is both necessary and sufficient condition for chaotic behaviour. Thus, since K-systems have positive KS-entropy while SM systems don’t, it is concluded that K-systems are chaotic whereas SM-systems are not. Why is KS-entropy a mark of chaos? There are three motivations, corresponding to three different interpretations of KS-entropy. First, KS-entropy could be interpreted as entailing dynamical instability in the sense of having nearby divergence of nearby trajectories (see Lichtenberg &amp; Liebermann, 1992, p. 304). Second, KS-entropy could be connected to algorithmic complexity (Brudno 1978). Yet, while such a complexity is sometimes mentioned as an indication of chaos, it is more difficult to connect it to physical intuitions about chaos. Third, KS-entropy could be interpreted as a generalized version of Shannon’s information theoretic entropy (see Frigg 2004). According to this approach, positive KS-entropy entails a certain degree of unpredictability, which is sufficiently high to deserve the title  chaotic.[24]