Examples and non-examples of polyhedral Kähler surfaces

Examples of Hyper - Kähler Connections with Torsion

The internal space of a N=4 supersymmetric model with Wess-Zumino term has a connection with totally skew-symmetric torsion and holonomy in Sp(n), i.e. a HKTconnection. We study the mathematical background of this type of connections and provide several examples to illustrate the theory.

Examples of non-quasicommutative semigroups decomposed into unions of groups

Decomposability of an algebraic structure into the union of its sub-structures goes back to G. Scorza's Theorem of 1926 for groups. An analogue of this theorem for rings has been recently studied by A. Lucchini in 2012. On the study of this problem for non-group semigroups, the first attempt is due to Clifford's work of 1961 for the regular semigroups. Since then, N.P. Mukherjee in 1972 studied...

Limit Surfaces of Riemann Examples

The only connected minimal surfaces foliated by circles and lines are domains on one of the following surfaces: the helicoid, the catenoid, the plane, and the examples of Riemann ([Ri] p329-33, [En] p403-6, [Ni] p85-6). All these surfaces are complete and embedded. Topologically they are planar domains: the helicoid is simply-connected, the catenoid is an annulus (conformally a twice-punctured ...

Examples of Smooth Non General Type Surfaces in P

Smooth projective varieties with small invariants have got renewed interest in recent years, primarily due to the fine study of the adjunction mapping by Reider, Sommese, Van de Ven and others. For the special case of smooth surfaces in P the method goes back to the Italian geometers, who at the turn of the century used it for the study of the surfaces of degree less than 7, or sectional genus ...

Some Examples of Smooth Non General Type Surfaces in P4