Einstein, Sasakian and Other Special Riemannian Manifolds

This issue is on the subject of Differential Geometry which has broad applications in areas of Physics, Chemistry and Engineering. The object of the volume are Riemannian manifolds endowed with additional geometric structure (eg: Einstein, Sasakian & Special Holonomy being typical examples). From a mathematical point of view, the additional structure implies conditions on the particular group of automorphisms leaving the Riemanniann manifold invariant, thus allowing a better understanding of the symmetries of the basic objects of study. This itself explains why the topic of the special issue is so relevant (particularly) in Physics, were theories are formulated from the imposed symmetries on fields and particles. Not all geometric structures are created equal in beauty and wealth. This issue is devoted to the ones which have shown a higher development in the last 50 years and which are more promising for future research.