On the kidney exchange problem: cardinality constrained cycle and chain problems on directed graphs: a survey of integer programming approaches

The Kidney Exchange Problem (KEP) is a combinatorial optimization problem and has attracted the attention from the community of integer programming/combinatorial optimisation in the past few years. Defined on a directed graph, the KEP has two variations: one concerns cycles only, and the other, cycles as well as chains on the same graph. We call the former a Cardinality Constrained Multi-cycle Problem (CCMcP) and the latter a Cardinality Constrained Cycles and Chains Problem (CCCCP). The cardinality for cycles is restricted in both CCMcP and CCCCP. As for chains, some studies in the literature considered cardinality restrictions, whereas others did not. The CCMcP can be viewed as an Asymmetric Travelling Salesman Problem that does allow subtours, however these subtours are constrained by cardinality, and that it is not necessary to visit all vertices. In existing literature of the KEP, the cardinality constraint for cycles is usually considered to be small (to the best of our knowledge, no more than six). In a CCCCP, each vertex on the directed graph can be included in at most one cycle or chain, but not both. The CCMcP and the CCCCP are interesting and challenging combinatorial optimization problems in their own rights, particularly due to their similarities to some travelling salesman- and vehicle routing-family of problems. In this paper, our main focus is to review the existing mathematical programming models and solution methods in the literature, analyse the performance of these models, and identify future research directions. Further, we propose a polynomial-sized and an exponential-sized mixed-integer linear programming model, discuss a number of stronger constraints for cardinality-infeasible-cycle elimination for the latter, and present some preliminary numerical results.     

The thickness of the complete multipartite graphs and the join of graphs

The thickness of a graph is the minimum number of planar spanning subgraphs into which the graph can be decomposed. It is known for relatively few classes of graphs, compared to other topological invariants, e.g., genus and crossing number. For the complete bipartite graphs, Beineke et al. (Proc Camb Philos Soc 60:1–5, 1964) gave the answer for most graphs in this family in 1964. In this paper, we derive formulas and bounds for the thickness of some complete k-partite graphs. And some properties for the thickness for the join of two graphs are also obtained.     

Betting Decision Under Break-Streak Pattern: Evidence from Casino Gaming

Cognitive bias is prevalent among gamblers, especially those with gambling problems. Grounded in the heuristics theories, this study contributes to the literature by examining a cognitive bias triggered by the break streak pattern in the casino setting. We postulate that gamblers tend to bet on the latest outcome when there is a break-streak pattern. Moreover, three determinants of the betting decision under break-streak pattern, including the streak length of the alternative outcome, the frequency of the latest outcome, and gender, were identified and examined in this study. A non-participatory observational study was conducted among the Cussec gamblers in a casino in Macao. An analysis of 1229 bets confirms our postulation, particularly when the streak of the alternative outcome is long, the latest outcome is frequent, and the gamblers are females. The findings provide meaningful implications for casino management and public policymakers regarding the minimization of gambling harm.     

Gambling Patterns and Problems of Gamblers on Licensed and Unlicensed Sites in France

In 2010 France enacted a law to regulate supply and consumption of online gambling. Its primary aim was to protect citizens from gambling-related harm. This study aims to assess differences in gambling patterns and related harm between online gamblers who use licensed versus unlicensed sites. Participants (N = 3860) completed a self-administered online survey on gambling practices. Pairwise logistic regressions examined the association between the legal statuses of gambling sites people patronized and demographic variables and gambling types. Multivariate logistic regression models explored associations between gambling patterns and related problems according to the legal status of sites people have gambled on. Overall, 53.7 % of online gamblers report gambling exclusively on licensed sites. Those who bet on regulated activities on unlicensed sites, versus licensed sites, are more likely to be female, younger, less educated, inactive in the labor market and are more likely to perceive their financial situation to be difficult. Gambling on unlicensed sites is associated with more intense gambling patterns and more gambling-related problems compared to licensed sites. Findings demonstrate that gambling activities carried out on state licensed sites are associated with less overall harm to gamblers. Implications of these findings on future policy are discussed and prospective research directions are outlined.     

Effects of Parental Divorce on Teenage Children’s Risk Behaviors: Incidence and Persistence

It is generally difficult to separate the effects of divorce from selection when analyzing the effects of parental divorce on children’s risk behaviors. We used propensity score matching and longitudinal data methods to estimate the effects of parents’ divorce on their children’s binge drinking, alcohol consumption, tobacco use, marijuana use, and hard drug use. The children were between 12 and 18 years old in the first survey and between 18 and 24 years old in the second survey. Our results suggest that parental divorce significantly increased the probability of risk behaviors in their children. Moreover, many of these adverse impacts persisted over time, especially among teenage girls.     

The Association of Alternative Financial Services Usage and Financial Access: Evidence from the National Financial Capability Study

This study examined the association of financial access and alternative financial services (AFS) using a nationally representative sample from the 2012 National Financial Capability Study (N = 25,509). Structural equation modeling was used to examine the relationship between financial access and AFS usage. Ordinary least squares regression was used to estimate the relationship between banked status and the overall AFS usage as a latent variable while controlling for sociodemographic variables, financial education, financial knowledge, and home ownership. Results suggested that being unbanked was positively associated with AFS usage after controlling for other covariates. Financial education and knowledge, age, gender, marital status, education, household income, and homeownership were significantly associated with AFS usage. These findings have implications for public policy and programs that work with the unbanked.     

Financial Education is not Enough: Millennials May Need Financial Capability to Demonstrate Healthier Financial Behaviors

Financial education sans opportunities for hands-on experience and knowledge operationalization may be insufficient for promoting healthy financial behaviors. Financial capability combines financial education with financial inclusion via a savings account, thereby giving an opportunity translate knowledge into practice. This study used data from the 2012 National Financial Capability Study to examine relationships between the financial capability and financial behaviors of United States Millennials (N = 6865). Compared to their financially excluded peers, Millennials who were financially capable were 176 % more likely to afford unexpected expenses, 224 % more likely to save for emergencies, 21 % less likely to use alternative financial services, and 30 % less likely to carry burdensome debt. Interventions that focus solely on financial education or inclusion may be insufficient for facilitating Millennials’ healthy financial behaviors; interventions should instead develop financial capability.     

A Decade of Change: Measuring the Extent,Depth and Severity of Food Insecurity

Rates of food insecurity in the US have been rising since 2000 spiking with the onset of the Great Recession in 2008, and have remained essentially unchanged since then despite improvements in the economy. The present study employed a series of indices adapted from the poverty literature to examine the depth and severity of food insecurity across the decade by race and ethnicity among low-income households with and without children. The most rapid increases in the depth and severity of food insecurity were found among low-income households without children. Non-Hispanic White households with and without children had lower prevalence rates but steeper increases in the depth and severity of food insecurity throughout the decade. Non-Hispanic Black households with and without children were at the most disadvantaged among low-income populations.     

Co-morbidity Between Gambling Problems and Depressive Symptoms: A Longitudinal Perspective of Risk and Protective Factors

In both adolescents and adults, gambling problems and depressive symptoms co-occur and share some common risk factors (e.g., impulsivity and socio-family risk). However, little is known about (1) the developmental course of the co-morbidity of these problems; (2) variables that may moderate the effect of these common risk factors on gambling problems and depressive symptoms. Of specific interest could be individuals’ social relationships with significant others such as parents and friends, because research shows that they moderate the effect of other risk factors on gambling problems and depressive symptoms. The goals of this study were to: (a) identify developmental pathways for gambling problems and depressive symptoms, with a focus on co-morbidity; (b) assess the moderating effect of relationship quality with parents and friends on the link between common risk factors and the trajectories of gambling problems and depressive symptoms. Study participants were 878 males. Predictors were assessed during childhood and adolescence and gambling problems and depressive symptoms were assessed in late adolescence and young adulthood. Latent class analysis revealed four distinct joint trajectories of gambling problems and depressive symptoms. Subsequent logistic regression revealed that impulsivity predicted membership in all pathogenic trajectories, and quality of the relationship with parents predicted membership in depressogenic trajectories. In addition, we found that the membership in the comorbid trajectory can be predicted by an interaction between friendship quality and socio-family risk.