On the Jordan-H\"older property for geometric derived categories
  We prove that the semiorthogonal decompositions of the derived category of the classical Godeaux surface X do not satisfy the Jordan-H\"older property. More precisely, there are two maximal exceptional sequences in this category, one of length 11, the other of length 9. Assuming the Noetherian property for semiorthogonal decompositions, one can define, following Kuznetsov, the Clemens-Griffiths component for each fixed maximal decomposition. We then show that D^b (X) has two different maximal decompositions for which the Clemens-Griffiths components differ. Moreover, we produce examples of rational fourfolds whose derived categories also violate the Jordan-H\"older property. 
Christian B\"ohning, Hans-Christian Graf von Bothmer, Pawel Sosna
math.AG math.CT