On complex algebras of subalgebras
  We establish a condition (so called generalized entropic property), equivalent to the fact that for every algebra A from a given variety V, the set of all subalgebras of A is a subuniverse of the complex algebra of A. We investigate the relationship between the generalized entropic property and the entropic law. Further, we study the identities satisfied by the complex algebras of subalgebras of algebras from a variety V. 
Kira Adaricheva, Agata Pilitowska and David Stanovsky