Complexity Theory: Key Concepts

This live streaming event will explore the core concepts in the theory of complex systems. During this 30-40 min presentation, Joss Colchester will introduce you to the framework used at Systems Innovation to structure and make sense of this powerful and exciting new set of ideas. The emphasis will be on understanding how these ideas integrate and fit together so that you get some view of the forest and not just the trees.
Topics will include:
Complex systems, what are they?
Self-organization, how does it work?
Nonlinearity and chaos explained.
Networks the architecture of complex systems.
Adaptation, evolution, Cybernetics and more.

[justLeito]

Thank you for great introduction. In my early twenties I was fascinated by work of Ilya Prigigine and read his all books. They highly influenced my way of thinking and aligned it to be more aligned with the reality, which is my life long goal - develop a framework of thinking that is as close as possible to reality. It was great to hear the name Ilya Prigogine again after so many years.

Could you recommend a simply written book(s) about complex systems with applications to social sciences/economics?
Thank you again!

[geordie]

Having thought about it overnight, here is a review with questions. In short, jolly interesting, but where is complexity defined? Complexity means different things to different people. And SIMPLE systems can have the properties attributed to complex ones.

COMPLEXITY THEORY?

Complexity science may be defined as:

-1- a set of mathematical models for complex systems: many parts, many connections or dependencies.

-2- a study of activity systems in which parts are actors with degree of autonomy.

-3- a study of structural patterns, observed or envisaged. Especially any structural pattern that appears in the state of an activity system. E.g. The pattern in leaf, or a flock of geese.

BUT NOTE: a structural pattern isn’t itself an activity system. E.g. A road network is not the rules used by traffic on it.

And the application of mathematical models to social entities can be problematic.

NETWORK STRUCTURES (network types, structures, graph theory)

About the connectivity in a topology (road, rail, canal, communication, social network); measures include: average path lengths, centrality.

Some say the topology is the “architecture” of a complex system; system rules and dynamics change as the connectivity increases.

BUT there are SIMPLE networks; a network differs from systems it enables, and a SIMPLE system can run over a complex network.

ADAPTATION (cybernetics, game theory, evolution)

Dynamic systems change over time, typically in response to changes in their environment.

BUT SURELY one must distinguish homeostatic self-regulation (as in cybernetic control systems) from progressive self-regulation (as the development of leaf pattern), and system mutation (as in biological evolution)?

You can have SIMPLE self-regulating systems (e.g. predator-prey). You can have SIMPLE games.

NON-LINEAR SYSTEMS (feedback, chaos, instability)

Non-linearity arises from inter-dependencies or synergies between parts.

Negative feedback (is in homeostasis) is said to be linear (though it may oscillate around a norm)

Positive feedback (as in progressive state change) is said to be non-linear.

Non-linear exponential growth is unsustainable, must crash, or flip to a new regime or configuration. E.g. heated water flips from liquid to gas.

Chaos: meaning a system’s state trajectory is very sensitive to initial conditions. E.g. Butterfly flaps wings > positive feedback > Tornado.

BUT why say one state change trajectory is more complex than another?

SIMPLE systems can have positive feedback and chaotic state change.

SELF-ORGANISING (emergence, synchronization, pattern formation)

Emergence requires relationships between parts that are not simply additive; the whole being organized greater or less than the sum of its parts

Coherent patterns can emerge from local interactions between autonomous actors. E.g. In a flock of geese, each bird operates under a few simple rules.

BUT emergence is found in SIMPLE systems. It isn’t specific to complex or self-organizing systems.

And why say organization by autonomous actors is more "complex" than organization imposed on those agents?

Order from disorder

Some characterize complex systems by the emergence of order (unorganized to organized, disorder to order, high entropy to low entropy.)

Energy is turned into organization; order grows in proportion to the amount of chaos dissipated.

BUT SURELY order emerges in SIMPLE systems (e.g. a flock of geese)?

And what about maintaining order in an already-orderly system? Is that not also self-organizing?

[neomotsoai]

This is quite informative, thank you.

[kylehiggins]

This was a great lecture, subscribed! Do you have a recommendation for a good introductory book that's mathematically rigorous? Kind of the opposite of the non quantitative skills question.

[dalehjify]

Thank you for the video. the link for the guides is no longer working. Would it be possible to get an updated link :)?

[noGPSdata]

I'd like to see the guide/ppt you've made

[Nick_Lyall]

The link to the accompanying PDF in the video description doesn't work anymore. Could you please provide a new link?

[samuelcorp]

What do you mean by a phase transition being discontinuous?

[nafisahbilao]

What is the central idea of Complexity Theory of Larsen-freeman?

[mlinganimatiwane]

hey guys thanks for the talk but the links don't work

[rupeshtashildar]

Complexity of a system is relative to the amount of information the observer has about the system; If we have all the information of how the parts behave in a complex system then that system can be treated as a simple system, similarly if we have very little information about the interaction of the parts in a simple system then that system is a complex system; Complexity is nothing but our inability to reduce a system to its parts.

[devendramishra]

Is human evolution a basis for complexity theory?

[yitphady]

It nothing wrong with iam not stupid I f iam stupbin you think I save money almost 20000.00 work two year and had car . Too . But this people try try to fuck my head talking very loud about me. I dont like people talk about what are you guy looking why you just come asking me my Canadian ziyticent . Dont mean not nothing .

[yitphady]

I spoke nice already talk nice to them already . Did I tell you iam not kids I have gread kids . .