Re: Any non-biological complex systems?

Posted by Stephen Guerin-5 on May 28, 2017; 5:00pm
URL: http://friam.383.s1.nabble.com/Any-non-biological-complex-systems-tp7589731p7589796.html

Though there are times, like in the context of machine learning, when we program algorithms to define ensembles of random systems along with ensembles of random models and select amongst them based on how well they fit observed data to find novel explanations for data for uses in prediction or classification. This might be related to past discussions on abductiion at FRIAM. Genetic Programming would be a related example.

Even though the systems in this case are defined randomly, given that they are selected for against some fitness function, the final systems used would probably still not constitute "arbitrary".

On Sun, May 28, 2017 at 10:39 AM, Stephen Guerin <[hidden email]> wrote:

So, what constitutes a system is arbitrary?  In the mind of the beholder?

 

I remember when we used to argue about this at The Complex.

 

I always wanted to argue that a system is in some sense “self-bounding”.  It consists of a group of entities that are interacting more intimately with one another than they are with entities outside the system. 

In the context of complex systems research, a system is an abstraction of a set of connected components and its boundary. The system's boundary can be defined as open, closed or isolated to flows of quantities of energy, mass, information, symbols etc. Defining information is a different thread ;-)

A model is the mathematical/computational formalization of the system.

Is what constitutes a system arbitrary?

George Box famously said "all models are wrong, but some are useful". Given that models are formalizations of systems and if arbitrary means: "based on random choice or personal whim, rather than any reason or system.", I would say researchers use reason and systemic thought to develop "useful" system descriptions. So, system descriptions are not arbitrary. They are designed to be useful for the question being asked. No system description nor model can answer all questions - they are specifically designed for a problem at hand.

Relatedly, a simulation, in the way we use it, is a single instance of a model run based on initializing  a model's parameters computing next states to observe its behavior/dynamics.

The phase space is the behavior of the model over all possible input states.

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