Mao, Xue Feng, Ghost length, cone length and complete level of DG modules, Acta mathematica Sinica. English series (Print) , 29(7), 2013, pp. 1279-1310
In this paper, we introduce a new numerical invariant complete level for a DG module over a local chain DG algebra and give a characterization of it in terms of ghost length. We also study some of its upper bounds. The cone length of a DG module is an invariant closely related with the invariant level. We discover some important results on it.