  Gelfond and Zhang recently proposed a new stable model semantics based on
Vicious Circle Principle in order to improve the interpretation of logic
programs with aggregates. The paper focuses on this proposal, and analyzes the
complexity of both coherence testing and cautious reasoning under the new
semantics. Some surprising results highlight similarities and differences
versus mainstream stable model semantics for aggregates. Moreover, the paper
reports on the design of compilation techniques for implementing the new
semantics on top of existing ASP solvers, which eventually lead to realize a
prototype system that allows for experimenting with Gelfond-Zhang's aggregates.
  To appear in Theory and Practice of Logic Programming (TPLP), Proceedings of
ICLP 2015.
