sentences:  In his unfinished work, Von Neumann also briefly considers conflict and interactions between his self-reproducing machines, towards understanding the evolution of ecological and social interactions from his theory of self-reproducing machines.In automata theory, the concept of a "universal constructor" is non-trivial because of the existence of Garden of Eden patterns.But a simple definition is that a universal constructor is able to construct any finite pattern of non-excited (quiescent) cells.