Signals and Boundaries Quotes

“Current studies of networks (Newman, Barabasi, and Watts 2006) using notions of community and synchrony within subgroups help to make the niche concept more precise. However, it is noteworthy that few network studies concentrate on the formation of boundaries within a network. And there is even less study of mechanisms for the formation of hierarchies—mechanisms that would explain the pervasiveness of hierarchies in natural systems.”
― John H. Holland, Signals and Boundaries: Building Blocks for Complex Adaptive Systems

“regardless of the details of the agent’s interior apparatus, a cas agent can always be defined in terms of a set of signal-processing rules called classifier rules. Each rule accepts certain signals as inputs (specified by the condition part of the rule) and then processes the signals to produce outgoing signals (the action part of the rule). Formally, both signals and boundaries can be defined using strings of “letters” drawn from one basic “alphabet.” This limited alphabet has a counterpart in cellular biology, where both the structure of protein signals and important parts of “gateways” in semi- permeable membranes are defined using an alphabet of twenty amino acids.”
― John H. Holland, Signals and Boundaries: Building Blocks for Complex Adaptive Systems