What's the regex corresponding to this DFA? Here is a DFA from a research project. We created the DFA manually.
We are interested in which regex is this DFA corresponding to.
Certainly, there could be multiple regex corresponding to it; we prefer a simpler one.



Inspired by the first answer from Karolis Juodelė, one correct Answer should be:

(00*10*1|1(0*|(10)*)*110*1)*1(0*|(10)*)*110*
$$(00^*10^*1 ~~~ | ~~~ 10^*(10)^*110^*1)^*~~~10^*(10)^*110^*$$
This should be one representation. Not sure if it could be made simpler. The part from $($ to $|$ represents one lap in the upper cycle. The part from $|$ to $)$ represents a lap in the lower cycle. The last part represents the path from $A$ to $D$.