Merge single floret edges.

[kasia-kobalczyk]

Say there are two consecutive florets A and B with only one emanating edge from each (say yes from A, and recovery from B):

... -> [A] -- yes--> [B] -- recovery --> [C] ...

Then this might be simplified to:

.... -> [A] -- yes & recovery --> [C] -> ...

Which would possibly make the graph less cluttered.

As an illustrative example I coded up the kidney liver disorder example from section 5.1.3 in the CEG J.Q.Smith's book.

The idea is to skip position w_6 and create a direct edge from w2 to w_\infty labelled yes & R with a probability of 0.75.