In 1988, Seiya Negami published a conjecture stating that a graph G has a finite planar cover (i.e. a homomorphism from some planar graph onto G which maps the vertex neighbourhoods bijectively) if and only if G embeds in the projective plane. Though the ”if” direction is easy, and over ten related research papers have been published during the past 20 years of investigation, this beautiful con...

For a Noetherian local domain (R, m, K), it is an open question whether strong F–regularity deforms. We provide an affirmative answer to this question when the canonical module satisfies certain additional assumptions. The techniques used here involve passing to a Gorenstein ring, using an anti– canonical cover.

Various observation- and reanalysis-based estimates of sea ice mass and ocean heat content trends imply that the energy imbalance of the Arctic climate system was similar [1.0 (0.9,1.2) Wm-2] to the global ocean average during the 2000-2015 period. Most of this extra heat warmed the ocean, and a comparatively small fraction went into sea ice melt. Poleward energy transports and radiation contri...

In a symmetric independent private values setting a sealed-bid double auction dissolves a partnership e¢ciently. This well known result remains valid in a model with interdependent valuations. However, if the interdependent components of valuations are large agents might prefer not to participate in a double auction. Therefore a simple extention of the rules of double-auctions is suggested that...

constraint bipartite vertex cover is a graph-theoretical formalization of the spare allocation problem for reconfigurable arrays. We report on an implementation of a parameterized algorithm for this problem. This has led to considerable simplifications of the published, quite sophisticated algorithm. Moreover, we can prove that the mentioned algorithm could be quite efficient in practial situat...

The number of studies seeking to empirically characterize the reduced-form relationship between a country economic growth and the quantity of various pollutants produced has recently increased significantly. In several cases researchers have found evidence in favor of an inverted-U “environmental Kuznets” curve. In the case of a major greenhouse gas, CO2, however, the evidence is at best mixed....

Understanding the cloud response to sea ice change is necessary for modeling Arctic climate. Previous work has primarily addressed this problem from the interannual variability perspective. This paper provides a refined perspective of sea ice-cloud relationship in the Arctic using a satellite footprint-level quantification of the covariance between sea ice and Arctic low cloud properties from N...

A Minimal Cover by Triples is an ordered pair (V, T ) where V is a finite set and T is a collection of three-element subsets of V with the properties that every pair of elements of V appear together in at least one element of T and if any element of T is removed, the first property no longer holds. In this paper we explore the possible values |T | can take on for a given |V |. In addition, cons...