Life in the Net

Open World Artificial Life Research

Adapted from Ackley (1996)

ccr breaks with most artificial life systems in a major way by presuming an open world, both in that humans are expected to interact with the system while it is running, and in that the underlying physical implementation---the computers and communications links---is expected to change dynamically. Three consequences of this approach are: Research strategies change because global repeatability is sacrificed, humans must be enticed to use the system, and the tradeoffs between security, efficiency, and power must be addressed, not only early and fundamentally, but continually and at many levels.

Repeatability is unscalable

A great virtue of closed-world alife models is that (at least in principle) every detail is determined by the researcher, so every observation can be reproduced, and utterly controlled variations can be tested. The price is that comparatively small worlds must be studied. With ingenuity, much has been and remains to be learned from such worldlets, and the possible richness of high-isolation worlds grows with improvements in affordable individual computers, but of course single-owner systems cannot compete with large collaborative networks of systems. The irony is that as computer systems become more like living systems---more complex and articulated, more robust and interconnected---they become less suited to closed-world artificial life research. Ray's NetTierra proposal offers one compromise position, in which repeatability is explicitly sacrificed but isolation is mostly preserved.

Humans are evolutionary forces

ccr approaches the dilemma another way, trading the isolated clarity of lab work for the symbiotic relevance of field work. ccr proposes to be a strictly non-proprietary experimental platform, controlled by and for its research users, providing a venue within which software for computation and communication tasks---``agents,'' ``brokers,'' ``robots,'' etc.---can be created, copied, hybridized, allowed to cooperate and compete for ``market share'' and perhaps win through into the base ccr standards and protocols.

As in typical alife systems, the overall ``fitness functions'' are supplied by humans; on the other hand, in ccr humans are also a source of novelty and change, conflicting with the Darwinian principle of blind variation. Given the nature of complex adaptive systems (Holland, 1995), and the gap between the manifest intentionality of the individual human action and the unintentional effects that often ensue, it is an empirical question just how un-Darwinian the evolution of a substantial ccr universe would actually be.

Security is biology

Communication entails risk (Ackley & Littman, 1994): A message sender necessarily reveals information in the act, and a message receiver is necessarily impacted in some way by the act, or else no communication has occurred. The dual tasks---of revealing some information while hiding some, and of allowing selected influences while rejecting others---are fundamental to the structure and function of living systems, from cell walls to immune systems, crucial to the very notions of self and independent existence.

A price exacted by the oft-touted mobility of a ``software agent'' is that it doesn't control the physical hardware that embodies it, so to protect its integrity it must either hide from or ally with the machine owner. Computer viruses take the former route; ccr takes the latter, committing to reveal to the owner the tradeoffs between safety and power as obviously and intuitively as possible, and placing its source code on the table as bona fides. In turn, in a general release of ccr, the hardware owners would commit to playing within the system (which includes researching attacks to devise defenses; in that spirit ccr 0.1 provides an ``award'' system to honor and memorialize the publicizers and fixers of holes), and would place their digital signatures on the table co-signed by existing ccr users (the bottom-up ``web of trust'' approach) and/or an appropriate external certification authority. Various flavors of anonymity can be created within the system, but only built upon a base of identified owners, shifting risk from loss of integrity to loss of anonymity. It is an open question whether special-purpose protected hardware could in principle be ``owned'' by the system itself, which could allow the construction of robust ``public spaces'' with known and reliable rules of behavior, inside of independently-owned computers---and if so, under what circumstances would wise owners choose to incorporate it.

While technologies such as digital signatures are necessary, security is much more than a purely technical issue, and so the purely technical power of the system must have corresponding limitations. In ccr, as in most high-isolation alife systems (e.g., Ray, 1991; Dewdney, 1984) as well as emerging commercial systems such as Java, the basic approach to limiting communication risk via limiting power is to control the semantics of the language in which communications are expressed. Though Java significantly improves security from the ``language on down'', as a general purpose programming language, its approach to trust is at the level of the program and is largely boolean---you either grant a disturbing amount of power to an incoming Java `applet' or you don't run it at all. As a research system, ccr sacrifices some speed and generality to gain fine-grained access control at multiple points including each function invocation, directly supporting intuitive and ccr-specific degrees and modes of trust and risk.

References

Ackley, D.H., & Littman, M.L. (1994): Altruism in the evolution of communication. In Artificial Life IV: Proceedings of the Fourth International Workshop on the Synthesis and Simulation of Living Systems. Edited by R. A. Brooks & P. Maes. A Bradford Book, The MIT Press: Cambridge, MA.
Ackley, D. H. (1996, to appear).: ccr: A Network of Worlds for Research. In Artificial Life V, MIT Press.
Dewdney, A.K. (1984, May): In the game called Core War hostile programs engage in the battle of bits. Scientific American. See also online, e.g.
Gosling, J. and McGilton, H. (1995, May).: The Java Language Environment: A White Paper., Sun Microsystems Computer Company. At the Java site.
Holland, J. H. (1995): Hidden Order: How Adaptation Builds Complexity. Addison-Wesley: Reading, MA.
Ray, T. S. (1995): A proposal to create a network-wide biodiversity reserve for digital organisms. ATR Technical Report TR-H-133. Was available online at, but now (July 4, 1996) seems to have been withdrawn.
Ray, T. S. (1991): An approach to the synthesis of life. In Artificial Life II, SFI Studies in the Sciences of Complexity, vol. X, edited by C. G. Langton, C. Taylor, J. D. Farmer, & S. Rasmussen, Addison-Wesley, 371--408.