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 w

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