Asynchronous sequential circuits
1) First assume the yellow signal is 0
2) Evaluate the rest of the signals based on (1)
3) From 2 you can get two outcomes: Either it is consistent - then it is a stable state. Or you get a contradiction and have a logically impossible combination (I.e. end up with yellow signal has to be 1). In this case it is a stable state.
4) Repeat 2-3 with the yellow assumed 1.  

Done.