A two-phase algorithm for bin stretching with stretching factor 1.5

Online Bin Stretching is a semi-online variant of bin packing in which the algorithm has to use the same number of bins as an optimal packing, but is allowed to slightly overpack the bins. The goal is to minimize the amount of overpacking, i.e., the maximum size packed into any bin.We give an algorithm for Online Bin Stretching with a stretching factor of 1.5 for any number of bins. We build on previous algorithms and use a two-phase approach. However, our analysis is technically more complicated and uses amortization over the bins with the help of two weight functions.     

Flora of the tram tracks of Bratislava

Urban Ecosystems - Tram and railway tracks represent specific urban habitats, which host a specific type of flora. This study aims to compile the information about species composition of flora of...     

Delegation and motivation

We investigate the determinants of decision rights transfer and its effects on the motivation of an agent. The study is based on a laboratory experiment conducted on 130 subjects playing an innovative principal–agent game. Interestingly, the results show that agents do not favour a delegation and a decision is considered rather burdensome. Although the experiment could not give support for the behavioural hypothesis of higher effort provided by participants who receive choice subsequently, the survey illuminates the interaction between delegation motives, effort motivators, goals and other perceptions of the agents.     

City parks vs. natural areas - is it possible to preserve a natural level of bee richness and abundance in a city park?

Urbanisation is an expansive process and a majority of insects live in human-modified areas. At the same time, a decrease in pollinator species richness and abundance has recently been observed in Europe, which in turn may have serious ecological and economic consequences. This study investigates the abundance, species richness and functional traits of wild bees in urban city parks in comparison to natural areas. The aim of this research was to assess the potential conservation values of urban green areas for bees. The present study demonstrates that a large and diversified city park may be a favourable habitat for bees, comparable to the natural fauna both in terms of the number and abundance of bee species. However, the study also showed that there were differences in the occurrence of species with different functional traits in the city parks investigated and in the natural landscape.     

A tighter insertion-based approximation of the crossing number

Let G be a planar graph and F a set of additional edges not yet in G. The multiple edge insertion problem (MEI) asks for a drawing of \(G+F\) with the minimum number of pairwise edge crossings, such that the subdrawing of G is plane. Finding an exact solution to MEI is NP-hard for general F. We present the first polynomial time algorithm for MEI that achieves an additive approximation guarantee—depending only on the size of F and the maximum degree of G, in the case of connected G. Our algorithm seems to be the first directly implementable one in that realm, too, next to the single edge insertion. It is also known that an (even approximate) solution to the MEI problem would approximate the crossing number of the F-almost-planar graph \(G+F\), while computing the crossing number of \(G+F\) exactly is NP-hard already when \(|F|=1\). Hence our algorithm induces new, improved approximation bounds for the crossing number problem of F-almost-planar graphs, achieving constant-factor approximation for the large class of such graphs of bounded degrees and bounded size of F.     

Economic Growth,Inequality and Poverty in the EU

Social Indicators Research - A country’s poverty rate is influenced by numerous factors, including economic growth and the distribution of its effects. This article aims to classify European...