In the heroic epoch of Causality Theory, the problems concerning the smoothability of time functions and Cauchy hypersurfaces remained as unanswered folk questions. Just recently solved, our aim is to discuss the state of the art on this topic, including self-contained proofs for questions on causally continuous, stably causal and globally hyperbolic spacetimes.

Art is defined as expression or application of human creative skill and imagination producing works to be appreciated primarily for their aesthetic value or emotional power. This definition encompasses two very important elements-the creation and reception of art-and by doing so it establishes a link, a dialogue between the artist and spectator. From the evolutionary biological perspective, act...