Enter derivation rules
A derivation rule maps single characters to output strings
The starting string is called
w. You must have exactly one derivation rule for
This is very similar to yesterday's post. See that page for an explanation
The big difference between yesterday and today is that probabilistic rules are now allowed. Write a number between 0 and 1 before the colon to specify that rule's probability.
Further reading: Chapter 1.7 of The Algorithmic Beauty of Plants