Lindenmayer - system, or LSystem for short is a parallel rewriting system, namely a variant of a formal grammar, most famously used to model the growth processes of plant development, but also able to model the morphology of a variety of organisms. L-Systems can also be used to generate self-similar fractals such as iterated function systems. L-systems were introduced and developed in 1968 by the Hungarian theoretical biologist and botanist from the University of Utrecht, Aristid Lindenmayer(1925–1989).

In these systems formal grammars are mapped to model 2d or 3d models, and later use of these has seen design - use of these systems, as you effectively can simulate generation of extreme numbers of possible design solutions in very short time. This is of course dependent on the LSystem being probabilistic rather then deterministic, as the latter produces the same output for every generation, every time. The book Algorithmic beauty of plants deals with LSystems in great detail, and is an essential read for anybody interested in this topic.

L - systems as described by Lindenmayer tried to enable the generation of models that could describe the complex growth process of plants. The notion of L-systems is a part of formal language theory, rooted in the theory of algorithms. The application of L-systems to plant description has been studied by biologists, and involves various methods of general mathematics. Self-similarity relates plant structures to the geometry of fractals. Computer-aided visualization of these structures, and the processes that create them, joins science with art. Being aware of these relations is important to appreciate the value of an L - System.

I must make a digression here to be able to continue. Now although this is a pretty rational and straightforward approach for me personally, I have to be aware that it may not be for others. That is why I am telling you here that while I was trying to explain ideas to people earlier, I started noticing patterns in my reasoning and rhetoric. It may sound obvious to some, but anyway I found that when I ran into parts of my ideas I could not explain with specific terms, it was because I did not have the right amount of understanding of the problem/solution making up the idea. In my case it would seem that the more I could use very specific language, I was also able to solve the problem and indeed convince others. This made me more aware of the power of language, grammars and words, which led me to theories surrounding formal languages, programming and L - systems. The connection here being that L – systems ( Lindenmayer systems) describe simulation of plant growth by formal grammar( A set of rules and symbols) which can be seen as a parallel to a design situation.

I see no reason why the act of making "replacement rules" for a genetic system could or should not be theorized in architectural design - by weighting different solutions(From micro to macro) in a design system, hence assigning parameters. This is already being done in parametric design. I have yet to see an Architectural project that uses this creatively though, like a probabilistic model for generation of a structure.

What is of great interest here is how many designs you can achieve from a validated starting point, like where the rules for development are somewhat agreed upon. There lies the potential because there would then come a process of selection of one or more of these designs. A system that would not produce the same result if you ran it several times for the same axiom(seed) would be extremely exciting. One would also prefer one that was context sensitive, that is - dependent of things like gravity, wind forces etc... A final criteria could be to have one that was parametric, meaning that elements of the systems' strings would have their own parameters, relating to the technical specifications of the Architectural design industry.

There is a twist here, though. It makes things a little less straight forward but it also makes the creative aspect much more interesting... I am referring to the "inference problem". Simply put it is not possible to know exactly what a given, probabilistic L-system will produce. Modifications of L-system' rules have been found to not be effective in producing a desired structure. That means you can not simply design with the end - product in mind, but it also means it is truly creative - or does it ? The answer to that may depend on the profession you are in but certainly pushing the limits of ones technical abilities should be creative ?

To make use of the potential of L - systems in 3 dimensional models, you use something like Turtle Graphics, and in many cases first by mapping words, or sequences of words to shapes.

More to follow.....