We consider space-times which in addition to admitting an isolated horizon also admit Killing horizons with or without an event horizon. We show that an isolated horizon is a Killing horizon provided either (1) it admits a stationary neighbourhood or (2) it admits a neighbourhood with two independent, commuting Killing vectors. A Killing horizon is always an isolated horizon. For the case when ...

tūbā et le sens de la nuit  publié en 1987 est un roman de šahrnūs pārsipūr, la romancière contemporaine. ce roman se classe d’emblé, non seulement, parmi les romans d’apprentissage mais aussi, dans la lignée des romans-fleuves. nous ignorons si l’écrivaine a créé cette forme romanesque malgré elle ou si elle en était consciente. dans notre étude, nous essayerons, à l’aide d’une nouvelle lectur...

This paper analyzes a connection between risk-sensitive and minimax criteria for discrete-time, nite-states Markov Decision Processes (MDPs). We synthesize optimal policies with respect to both criteria, both for nite horizon and discounted in nite horizon problem. A generalized decision-making framework is introduced, which includes as special cases a number of approaches that have been consid...

During any marine oil spill, floating oil slicks that reach shorelines threaten a wide array of coastal habitats. To assess the presence of oil near shorelines during the Deepwater Horizon (DWH) oil spill, we scanned the library of Synthetic Aperture Radar (SAR) imagery collected during the event to determine which images intersected shorelines and appeared to contain oil. In total, 715 SAR ima...

Issues of feasibility and stability are considered for a nite horizon formulation of receding horizon control for linear systems under mixed linear state and control constraints. We prove that given any compact set of initial conditions that is feasible for the innnite horizon problem, there exists a nite horizon length above which a receding horizon policy will provide both feasibility and sta...

Tacit knowledge, intuition, intuitive heritage are very broad concepts and sometimes too vague to provide for any practical applications (as a bird in the hand is worth two in the bush). Only some of the many possible intuitive factors in science are chosen. Indo-European mythology belongs to the heritage of humanity, but has nothing to do with the mathematical creation of set theory. It is pos...

We develop a unifying approach for approximating a \limit" zero-sum game by a sequence of approximating games. We discuss both the convergence of the values and the convergence of optimal (or \almost" optimal) strategies. Moreover, based on optimal policies for the limit game, we construct policies which are almost optimal for the approximating games. We then apply the general framework to stat...

The success of the big bang predictions for the abundances of the light elements suggests that the universe was already in thermal equilibrium at one second after the big bang. At this time, the region that later evolves to become the observed universe was, in the context of the conventional (non-inflationary) cosmological model, many horizon distances across. Try to estimate how many. You may ...

A widespread myth asserts that all small universe models suppress the CMB quadrupole. In actual fact, some models suppress the quadrupole while others elevate it, according to whether their low-order modes are weak or strong relative to their high-order modes. Elementary geometrical reasoning shows that a model’s largest dimension determines the rough value lmin at which the CMB power spectrum ...

We present in this paper several asymptotic properties of constrained Markov Decision Processes (MDPs) with a countable state space. We treat both the discounted and the expected average cost, with unbounded cost. We are interested in (1) the convergence of nite horizon MDPs to the innnite horizon MDP, (2) convergence of MDPs with a truncated state space to the problem with innnite state space,...