Stopper vs. Singular Controller Games With Degenerate Diffusions.

We study zero-sum stochastic games between a singular controller and a stopper when the (state-dependent) diffusion matrix of the underlying controlled diffusion process is degenerate. In particular, we show the existence of a value for the game and determine an optimal strategy for the stopper. The degeneracy of the dynamics prevents the use of analytical methods based on solution in Sobolev spaces of suitable variational problems.

Experimental test of the no-signaling theorem.

In 1981 N. Herbert proposed a gedanken experiment in order to achieve by the "First Laser-Amplified Superluminal Hookup" (FLASH) a faster-than-light (FTL) communication by quantum nonlocality. The present work reports the first experimental realization of that proposal by the optical parametric amplification of a single photon belonging to an entangled EPR pair into an output field involving N=5 x 10{3} photons.