written 8/9/2012 on a different space....
Disclaimer: This is as expected, incomplete and loosely written – but written none-the-less. I struggle with the obvious plagiarism in certain snippets – but wonder, who is this for anyway? Consider it my personal collection of quotes and ideas that are meaningful to me, and thoughts of my own.
Overview
What is complexity? I have been saying to myself and anyone else who would listen that I am primarily interested in solving, or at least working on complex problems. (trivial, mundane, or repetitive tasks are not my bowl of soup). Things that stir my interest are global issues in environmental sustainability, political, economic, social, human behavior and interaction, aiming to achieving a peaceful, tolerant, and sustainable world order. Issues where there are many people or system actors involved, making decisions based on either incomplete or imperfect information, sometimes with opposing goals, or at best not fully understood relationships, outcomes, nor consequences. How do we move an amorphous blob of Jello from point A to point B as efficiently as possible without killing each other? This problem inspires an understanding and respect for a view that we have to expect a degree of disorder, and sometimes seeming chaos as long as, on average, we can measure progress in the direction toward the goal sought.
Needless to say, my personal view of complexity is pretty broad and imprecise, perhaps as it should be.
Neil Johnson’s book obviously should provide a considerably stronger definition and structure to our concept of complexity. And it does. Neil starts by suggesting a distinction between what is complex as opposed to simply complicated. To condense what takes several chapters in Simply Complexity to describe a formal definition of complexity, I offer the following snippets:
Complexity Science: The study of phenomena that emerge from a collection of interacting objects (a crowd) often competing for a limited resource. Such phenomena, often surprising, sometimes catastrophic, emerge in the absence of any central controller or coordinator. The goal of Complexity Science is to answer whether these systems and their behavior are predictable and controllable so as to manage to avoid the catastrophes and optimize the desired outcomes.
Key components of Complexity:
The system contains a collection of many interacting objects.
These objects’ behavior is affected by memory, or feedback
The objects can adapt their strategies according to their history
The system is typically open – to external inputs and influences by is environment
The system appears to be alive – evolving in non-trivial ways
The system exhibits emerging phenomena that are generally surprising and sometimes extreme
The emergent phenomena arise in the absence of any invisible hand or central controller
The system exhibits a complicated mix of ordered and disordered behavior.
One key attribute of complex systems: In opposition to the second law of thermodynamics, Entropy – the tendency for all matter to move toward dis-order, rather than order, is that in a complex system order may arise out of disorder without central control.
A system with a collection of interacting agents (people or objects) (a crowd) that make decisions based on feedback (memory and information), often competing for some limited resource, resulting in emergent behavior that may be observed within a range of disorder and order.
Snippets:
P28. Collections of objects in the absence of any feedback tend to become increasingly disordered.
P28. The amount of disorder in a closed system increases over time
P28. Fortunately truly closed systems are very rare. In fact the Universe is the only truly closed system we know of.
Chaos, Complexity and Fractals.
Probably the most interesting, novel, concept to me in this read is a closer understanding of Chaos and fractals that I haven’t previously digested. In my own summary, it seems Chaos may be observed in a complex system whose output time series merely appears random for the moment, yet is based on the structure and dynamics of the complex system. A complex system can exhibit both ordered and chaotic behavior and anything between and the transition between order and chaos is itself complex.
Fractal: Well, more interesting is that chaos is really a periodic pattern in the time series output of a complex system in which the period is so long it seems to never repeat. Between linear, ordered systems and chaos is a family of dynamics called fractals that again are simply periodic patterns with, well, less than infintite period… The book does a nice job showing the broken pattern of resultant output numbers that can occur, illustrating that in certain fractal outputs the available numbers in the output series are elements of broken line segments, with an infinite number of possible valid values, and an infinite number of gaps, not to be observed in the output time-series. A nice paragraph to steal: “scientists refer to a point as zero dimensional, a line as being one-dimensional, and a flat sheet, or plane as two-dimensional. The fine dust of points which looks like a solid line but isn’t, is effectively between a point and a line – hence it is between a zero and a one-dimensional object. As we know a number between zero and one is a fraction – hence the fine dust of points has a fractional dimension. For this reason, scientists call an object such as this fine dust of points a fractal.”
The emergence of fractals is a common occurrence in complex systems.
As I skim the book for quotable gems, I recognize, as usual, that a re-read wouldn’t hurt. There always seems to be more in it and to it than the first pass digests. But alas, I am always in a rush to get onto the next project… and can only afford some final impressions.
The book provides numerous interesting and varied examples of research that has modeled complex systems and can demonstrate similar dynamics in their outputs as found in real world systems. Observations range from the shapes of coast lines, mountain ranges, biological growth and decay, and financial market price performance. I do recognize that there is value in modeling such dynamics and the ability in using these models to predict potential future behavior, though I am skeptical in several cases that, without taking real world input into consideration in the model, such as real, time based externalities of a global market events, while the model can predict the near term possible outcomes, it seems impossible to predict the Actual outcomes with a high degree of confidence. Modeling dynamics is not the same as modeling true value and actual expected behavior.
On System modeling – as I read this, I am imagining how I would model certain of these systems. Thinking these would be modeled as large collections of individual objects with certain attributes, relationships and behaviors. I’d write a event-time driven simulation to generate the time series output of the collective behaviors of interest. In reading the book, however, I get a different sense that the current research is resorting to aggregate models of the collective behaviors rather than individual objects. Again, it is likely appropriate and valuable, but assumes, which I think they justify, that such complex systems can be modeled as normally distributed agents.
Conclusion / Final Verdict / Recommendation:
In his introduction, Neil outlines 6 plus goals he wishes to accomplish with the book.I think he accomplishes all of his wishes to a fair degree. I certainly have come away with a comfortable sense of complexity theory and my mind is sowed with new seeds to be nurtured and hopefully harvested in future thoughts.
While accessible to the general reader and enlightening in the varieties of problems Complexity theory can contribute to, I think the book has a couple minor setbacks: redundancy, or seeming repetitiveness, and a little too superficial in seeming to use this book to promote the works of the various researchers. Both of these criticisms are probably too harsh, or should I say, really need to be considered very minor. The redundancy between topics and research areas is probably both very natural, and intentional in the structure of the book to show the commonality and inter-relatedness between vastly different problems, similarly modeled as complex systems. My criticism toward the survey of research and researchers too is probably slightly unfair as I recognize the value in giving due credit and respect to the contributors in the field, as well as the need to use such an approach in an introductory survey. I’m just saying it seemed to me these two issues created some drag in the flow and progress of the read