The minimum-entropy set cover problem

AbstractWe consider the minimum entropy principle for learning data generated by a random source and observed with random noise.In our setting we have a sequence of observations of objects drawn uniformly at random from a population. Each object in the population belongs to one class. We perform an observation for each object which determines that it belongs to one of a given set of classes. Given these observations, we are interested in assigning the most likely class to each of the objects.This scenario is a very natural one that appears in many real life situations. We show that under reasonable assumptions finding the most likely assignment is equivalent to the following variant of the set cover problem. Given a universe U and a collection S=(S1,…,St) of subsets of U, we wish to find an assignment f:U→S such that u∈f(u) and the entropy of the distribution defined by the values |f-1(Si)| is minimized.We show that this problem is NP-hard and that the greedy algorithm for set cover s with an additive constant error with respect to the optimal cover. This sheds a new light on the behavior of the greedy set cover algorithm. We further enhance the greedy algorithm and show that the problem admits a polynomial time approximation scheme (PTAS).Finally, we demonstrate how this model and the greedy algorithm can be useful in real life scenarios, and in particular, in problems arising naturally in computational biology

The effect of moral loss and gain mindset on confronting racism

In the present research, we tested whether the prospect of moral failure or moral gain can motivate (some) people to confront racism. We investigated the influence of moral loss and moral gain mindset on people's tendency to contest racism as a function of their moral commitment to non-prejudice.Drawing on research on regulatory focus, we predicted that a moral loss mindset (vs. control) would increase confronting tendencies among those who are morally committed to non-prejudice (to safeguard their moral self-concept). A moral gain mindset (vs. control) was expected to increase confronting among those who are less committed to non-prejudice (to enhance their moral self-concept). In Experiment 1, participants were presented with racist scenarios. We varied the framing of moral considerations involved (loss vs. gain vs. control) and assessed confronting intentions. In Experiment 2, participants went through a moral mindset intervention. After a few days, using a behavioral paradigm, we tested their actual confronting during a racist situation. We found partial evidence to our predictions. Those highly committed to non-prejudice (as indicated by a measure of moral conviction in Experiment 1, but by a measure of moral identity in Experiment 2) were significantly more prone to confront in the loss mindset condition than in the control. Confronting in the gain condition was not significantly different than in the control condition at any level of moral commitment to non-prejudice. These findings suggest that a moral loss mindset intervention may be effectively used in promoting (some) people's tendency to speak up against racism

Hope Comes in Many Forms: Out-Group Expressions of Hope Override Low Support and Promote Reconciliation in Conflicts

In conflicts, political attitudes are based to some extent on the perception of the out-group as sharing the goal of peace and supporting steps to achieve it. However, intractable conflicts are characterized by inconsistent and negative interactions, which prevent clear messages of out-group support. This problem calls for alternative ways to convey support between groups in conflict. One such method is emotional expressions. The current research tested whether, in the absence of out-group support for peace, observing expressions of out-group hope induces conciliatory attitudes. Results from two experimental studies, conducted within the Israeli–Palestinian conflict, revealed support for this hypothesis. Expressions of Palestinian hope induced acceptance of a peace agreement through Israeli hope and positive perceptions of the proposal when out-group support expressions were low. Findings demonstrate the importance of hope as a means of conveying information within processes of conflict resolution, overriding messages of low out-group support for peace

BayesCCE: a Bayesian framework for estimating cell-type composition from DNA methylation without the need for methylation reference.

We introduce a Bayesian semi-supervised method for estimating cell counts from DNA methylation by leveraging an easily obtainable prior knowledge on the cell-type composition distribution of the studied tissue. We show mathematically and empirically that alternative methods which attempt to infer cell counts without methylation reference only capture linear combinations of cell counts rather than provide one component per cell type. Our approach allows the construction of components such that each component corresponds to a single cell type, and provides a new opportunity to investigate cell compositions in genomic studies of tissues for which it was not possible before

Protected by the Emotions of the Group:Perceived Emotional Fit and Disadvantaged Group Members’ Activist Burnout

Psychological processes that hamper activism, such as activist burnout, threaten social change. We suggest that perceived emotional fit (i.e., perceiving to experience similar emotions as other disadvantaged group members) may buffer activist burnout by mitigating the deleterious effects of stressors that are associated with partaking in collective action. We investigated the relation between perceived emotional fit and activist burnout using three-wave longitudinal survey data of Palestinians in the context of the Palestinian–Israeli conflict. We hypothesized that both higher general tendencies to fit emotionally with the ingroup (general perceived emotional fit) and increases over time in perceived emotional fit (change perceived emotional fit) would relate negatively to activist burnout. Supporting our hypotheses, both aspects of emotional fit were associated with lower activist burnout, even when controlling for classical predictors of collective action. This research highlights perceived emotional fit as an additional dimension to the role of emotions for sustainable collective action.</p