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Lindenmayer systems

Lindenmayer systems (L-systems, turtle graphics) are used to generate
Fractal curves (Koch, Sierpinski, Levy, Dragon),
Space filling curves (Hilbert, Peano-Gosper),
Growth patterns in plants,
etc. It is an iterative string rewriting method. Starting from the Axioma a new string is formed
by replacing the string symbols according to a few given Rules.The final string contains
instructions
telling the turtle where to go, or how to draw the path.
The list contains a number of well known examples. Choose one of them and push
the Draw button to draw
it in the graphical window. You may construct your own examples and
add them to the list.
More information on Lindenmayer systems:

A Lindenmayer system is defined by an Axioma, one or more Rules and a list of Instructions
which tell the turtle what to do. The Axioma is a string (for example: F X + F - F) which may conatain Rules (X) and Instructions (F, +, -).
Rules may only contain Instructions. Starting from the Axioma a new string is formed by
replacing the string symbols according to the Rules and Instructions. This is repeated n times, where n is
called the Order of the system.
The final string contains ínstructions
telling the turtle where to go, or how to draw the path. The Axioma and the Rules may contain
the following instructions