Coalition Resilient Outcomes in Max k-Cut Games

We investigate strong Nash equilibria in the \emph{max $k$-cut game}, where we are given an undirected edge-weighted graph together with a set $\{1,\ldots, k\}$ of $k$ colors. Nodes represent players and edges capture their mutual interests. The strategy set of each player $v$ consists of the $k$ colors. When players select a color they induce a $k$-coloring or simply a coloring. Given a coloring, the \emph{utility} (or \emph{payoff}) of a player $u$ is the sum of the weights of the edges $\{u,v\}$ incident to $u$, such that the color chosen by $u$ is different from the one chosen by $v$. Such games form some of the basic payoff structures in game theory, model lots of real-world scenarios with selfish agents and extend or are related to several fundamental classes of games. Very little is known about the existence of strong equilibria in max $k$-cut games. In this paper we make some steps forward in the comprehension of it. We first show that improving deviations performed by minimal coalitions can cycle, and thus answering negatively the open problem proposed in \cite{DBLP:conf/tamc/GourvesM10}. Next, we turn our attention to unweighted graphs. We first show that any optimal coloring is a 5-SE in this case. Then, we introduce $x$-local strong equilibria, namely colorings that are resilient to deviations by coalitions such that the maximum distance between every pair of nodes in the coalition is at most $x$. We prove that $1$-local strong equilibria always exist. Finally, we show the existence of strong Nash equilibria in several interesting specific scenarios.Comment: A preliminary version of this paper will appear in the proceedings of the 45th International Conference on Current Trends in Theory and Practice of Computer Science (SOFSEM'19

A survey of orphan enzyme activities

<p>Abstract</p> <p>Background</p> <p>Using computational database searches, we have demonstrated previously that no gene sequences could be found for at least 36% of enzyme activities that have been assigned an Enzyme Commission number. Here we present a follow-up literature-based survey involving a statistically significant sample of such "orphan" activities. The survey was intended to determine whether sequences for these enzyme activities are truly unknown, or whether these sequences are absent from the public sequence databases but can be found in the literature.</p> <p>Results</p> <p>We demonstrate that for ~80% of sampled orphans, the absence of sequence data is bona fide. Our analyses further substantiate the notion that many of these enzyme activities play biologically important roles.</p> <p>Conclusion</p> <p>This survey points toward significant scientific cost of having such a large fraction of characterized enzyme activities disconnected from sequence data. It also suggests that a larger effort, beginning with a comprehensive survey of all putative orphan activities, would resolve nearly 300 artifactual orphans and reconnect a wealth of enzyme research with modern genomics. For these reasons, we propose that a systematic effort to identify the cognate genes of orphan enzymes be undertaken.</p

Minimum-weight perfect matching for non-intrinsic distances on the line

Consider a real line equipped with a (not necessarily intrinsic) distance. We deal with the minimum-weight perfect matching problem for a complete graph whose points are located on the line and whose edges have weights equal to distances along the line. This problem is closely related to one-dimensional Monge-Kantorovich trasnport optimization. The main result of the present note is a "bottom-up" recursion relation for weights of partial minimum-weight matchings.Comment: 13 pages, figures in TiKZ, uses xcolor package; introduction and the concluding section have been expande

Satisfaction with democracy in Turkey: findings from a national survey

A variety of factors affect citizens' satisfaction with democracy. Based on Turkey's political and economic context, as well as the existing literature, this study investigates the effect of four factors on people's satisfaction with democracy in Turkey: citizens' conceptualizations of democracy, being a political winner, citizens' perceptions of electoral integrity, and ethnic identity. Regression analysis of a nationally representative survey reveals that political losers and those with negative perceptions of electoral integrity are less satisfied with democracy in Turkey, while people's conceptualizations of democracy and ethnic identity do not have an effect on satisfaction with democracy. We conclude that, in Turkey, political polarization and negative perceptions of electoral integrity trigger a decline in citizens' satisfaction with democracy, which requires the attention of policymakers

Hamiltonicity below Dirac's condition

Dirac's theorem (1952) is a classical result of graph theory, stating that an $n$-vertex graph ($n \geq 3$) is Hamiltonian if every vertex has degree at least $n/2$. Both the value $n/2$ and the requirement for every vertex to have high degree are necessary for the theorem to hold. In this work we give efficient algorithms for determining Hamiltonicity when either of the two conditions are relaxed. More precisely, we show that the Hamiltonian cycle problem can be solved in time $c^k \cdot n^{O(1)}$, for some fixed constant $c$, if at least $n-k$ vertices have degree at least $n/2$, or if all vertices have degree at least $n/2-k$. The running time is, in both cases, asymptotically optimal, under the exponential-time hypothesis (ETH). The results extend the range of tractability of the Hamiltonian cycle problem, showing that it is fixed-parameter tractable when parameterized below a natural bound. In addition, for the first parameterization we show that a kernel with $O(k)$ vertices can be found in polynomial time

Information effect on voter turnout: How campaign spending mobilises voters

We explore the impact of campaign effort on constituency-level turnout variation in Britain, under the premise that higher levels of campaign visibility stimulate electoral participation. We focus on the relationship between the competitiveness of the race and campaign effort as a provider of electoral information on the one hand, and voter turnout on the other hand. In doing so, we address the role of campaign effort and competitiveness in shaping turnout both independently as well as jointly. Further to this, we seek to add nuance to our understanding of how electoral campaigns mobilise voters by evaluating the comparative ability of different parties – based on whether or not they are ‘viable’ contenders in a particular constituency – to stimulate turnout. We find evidence that campaign effort mobilises voters and has a significant positive effect on voter turnout; this effect is independent from, and unconditioned by, the competitiveness of the race. However, we do find that this effect is mostly driven by the campaign effort of the ‘viable’ contenders in the constituency

Information effect on voter turnout: How campaign spending mobilises voters

We explore the impact of campaign effort on constituency-level turnout variation in Britain, under the premise that higher levels of campaign visibility stimulate electoral participation. We focus on the relationship between the competitiveness of the race and campaign effort as a provider of electoral information on the one hand, and voter turnout on the other hand. In doing so, we address the role of campaign effort and competitiveness in shaping turnout both independently as well as jointly. Further to this, we seek to add nuance to our understanding of how electoral campaigns mobilise voters by evaluating the comparative ability of different parties – based on whether or not they are ‘viable’ contenders in a particular constituency – to stimulate turnout. We find evidence that campaign effort mobilises voters and has a significant positive effect on voter turnout; this effect is independent from, and unconditioned by, the competitiveness of the race. However, we do find that this effect is mostly driven by the campaign effort of the ‘viable’ contenders in the constituency

Milk: the new sports drink? A Review

There has been growing interest in the potential use of bovine milk as an exercise beverage, especially during recovery from resistance training and endurance sports. Based on the limited research, milk appears to be an effective post-resistance exercise beverage that results in favourable acute alterations in protein metabolism. Milk consumption acutely increases muscle protein synthesis, leading to an improved net muscle protein balance. Furthermore, when post-exercise milk consumption is combined with resistance training (12 weeks minimum), greater increases in muscle hypertrophy and lean mass have been observed. Although research with milk is limited, there is some evidence to suggest that milk may be an effective post-exercise beverage for endurance activities. Low-fat milk has been shown to be as effective, if not more effective, than commercially available sports drinks as a rehydration beverage. Milk represents a more nutrient dense beverage choice for individuals who partake in strength and endurance activities, compared to traditional sports drinks. Bovine low-fat fluid milk is a safe and effective post exercise beverage for most individuals, except for those who are lactose intolerant. Further research is warranted to better delineate the possible applications and efficacy of bovine milk in the field of sports nutrition

Lack of HLA predominance and HLA shared epitopes in biliary Atresia

Biliary atresia (BA) is characterized by progressive inflammation and fibrosis of bile ducts. A theory of pathogenesis entails autoimmune-mediated injury targeting bile duct epithelia. One of the strongest genetic associations with autoimmunity is with HLA genes. In addition, apparently dissimilar HLA alleles may have similar antigen-binding sites, called shared epitopes, that overlap in their capacity to present antigens. In autoimmune disease, the incidence of the disease may be related to the presence of shared epitopes, not simply the HLA allelic association. Aim: To determine HLA allele frequency (high-resolution genotyping) and shared epitope associations in BA. Results: Analysis of every allele for HLA-A, -B, -C, -DRB1, -DPB1 and -DQB1 in 180 BA and 360 racially-matched controls did not identify any significant HLA association with BA. Furthermore, shared epitope analysis of greater than 10 million possible combinations of peptide sequences was not different between BA and controls. Conclusions: This study encompasses the largest HLA allele frequency analysis for BA in the United States and is the first study to perform shared epitope analysis. When controlling for multiple comparisons, no HLA allele or shared epitope association was identified in BA. Future studies of genetic links to BA that involve alterations of the immune response should include investigations into defects in regulatory T cells and non-HLA linked autoinflammatory diseases. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2193-1801-2-42) contains supplementary material, which is available to authorized users