Selected and commented by Gérard Weisbuch under his own reponsability.

Complexity and complex systems have different meanings according to authors. I will stress in the comments the interpretation specific to the corresponding site.

NEWS

• The comdig site (Complexity Digest) publishes every week a large set of news from the scientific literature (e.g. Nature, Science etc...). The accent is on real complex systems in Biology, Physics etc. rather than models.
• The Econophysics site publishes every day a set of preprints posted on the Los Alamos web site. Most of these preprints concern models of economic systems and other phenomena; numerical simulations and formal solutions are presented.

European Collaborations sites

• EXYSTENCE was the first collaboration on Complex systems from 2001 to 2006. The site is still maintained by Nigel Gilbert and offers a number of resources on events, people and a Road Map (assesment of the advances in complex systems written by important scientists in the field).
• ONCE-CS is more recent (from 2005) and offers features comparable to EXYSTENCE and to the present site.
• Agent Link is the European collaboration on Agent Based Computing.

The agent perspective

To many people, especially in computer science, the preferred way to model complex systems is through agent based simulation, often implemented in object languages.

• ACE (Agent-Based Computational Economics) maintained by Leigh Tesfastion is representative of the agent based perspective among economists.
• Denis Phan, a french connection.

Simulation platforms

Agent simulators are often fond of simulation platforms with the idea that an available platform is more useful to biologists or social scientists than direct programming. Among the many options, let me cite a few; anyway several sites give pointers to many more platforms.

• SWARM, built by Chris Langton and his colleagues in the Santa Fe Institute, was among the first platforms. It is still widely used. The site offer links to more platforms.
• ASCAPE was developped from the sugarscape collaboration
• CORMAS was built by a french collaboration.

Re-usable software

Being able to re-use sofware written by fellow scientists looks kind of a dream, although this is exactly what we are doing when using software libraries. In fact an excellent resource was proposed by Gary Flake who put on his web site the set of programs in C that he used for his book the Computational Beauty of Nature. The programs are well written and documented (+ the book).

Book reports

Cosma Shalizi reported on a large number of books, including some about complex systyems.

Institutions

• The site of the Brookings Institution contains interesting material (preprints and computer programs), e.g. written by Josh Epstein and Rob Axtell.
• The Santa Fe Institute is by far the most important institution on complex systems. Its web site contains a lot of info on people, events, a large preprint repository, and some news relative to the institute through its bulletin.

On line Journals

JASSS, the Journal of Artificial Societies and Social Simulation edited by Nigel Gilbert contains a lot of material on Simulating Societies.