Because of their variability, ability to heal and self-reproduce, and so on, organisms are defined as 'meta-systems' of simpler systems in CSB.[1][14] A meta-system is a system of systems.[14] Autopoiesis also models such a biological system of systems,[15] however, Baianu et al. claim that in biology a meta-system is not equivalent to such a system of systems.[5] They also claim it differs from the meta-system defined in a blog by Kent D. Palmer[16][17] because organisms are different from machines or robots.[5] If, according to Hopcroft et al., robots or automata can be defined by five qualities: states, startup state, input and output sets/alphabet and transition function,[18] organisms are different.[5]