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Atanassov's intuitionistic fuzzy sets (IFSs) are a very convenient tool for describing alternatives/options while making decisions because they make it possible to naturally represent the pros, cons, and hesitation. The IFSs have attracted a significant interest and have been applied in various fields. Of course, their use poses some challenges. One of the main challenges is the ranking of alternatives/options described by the intuitionistic fuzzy sets, to be called for brevity the intuitionistic fuzzy alternatives. This is a crucial issue, notably for the applications, for instance, in decision making. We first present in detail and analyze the benefits of a method we introduced previously (cf. Szmidt and Kacprzyk [1]). For this method, we augment the original assumptions with an additional assumption, which is justified and inherently reasonable. As a result, we obtain formulas which are better justified than those previously used as they explicitly consider the arguments in favor (pro), against (con), and hesitance. Since the intuitionistic fuzzy alternatives can not be linearly ranked, then the additional assumptions during the ranking process are necessary. We address these issues and analyze examples to clarify our new approach. We examine some other methods discussed in the literature and analyze their results, and show that the new assumptions reconcile some misconceptions raised by those other papers. [ABSTRACT FROM AUTHOR]

We discuss some aspects of similarity measures in the context of Atanassov's intuitionistic fuzzy sets (IFSs, for short). IFSs, proposed in 1983, are a relatively new tool for the modeling and simulation and, because of their construction, present us with new challenges as far the similarity measures are concerned. Specifically, we claim that the distances alone are not a proper measure of similarity for the IFSs. We stress the role of a lack of knowledge concerning elements (options, decisions, etc.) and point out the role of the opposing (complementing) elements. We also pay attention to the fact that it is not justified to talk about similarity when one has not enough knowledge about the compared objects/elements. Some novel measures of similarity are presented. [ABSTRACT FROM AUTHOR]

Introduction. Patients considered for radical surgery for lung cancer need a functional evaluation to identify those at increased risk of postoperative complications. Material and methods. We performed an analysis of clinical data of 1214 patients who underwent a single lobectomy for lung cancer. To assess the risk of complications, we used the chronic obstructive pulmonary disease assessment test (CAT). Results. 254 pulmonary and 51 cardiovascular complications occurred in 216 (17.8%) patients. In 204 patients with a CAT score ≥12 complications occurred more often than in patients with a lower score (26.5% vs. 16.0%; p < 0.001). Conclusions. In patients undergoing lobectomy for lung cancer, pulmonary complications occurred much more frequently than cardiovascular complications. Patients with a CAT score ≥12 had a higher rate of postoperative complications as compared to those with a lower score. [ABSTRACT FROM AUTHOR]

We propose a mathematical model of the N -person prisoner's dilemma game played by a continuous population of agents with a time-dependent aspiration level. The model-a system of differential equations-takes into account the evolution of the aspiration level and of the mean frequency of the cooperators in the population. The dependence of the asymptotic level of cooperation on the individual payoffs and on the transition rates determining the agent's reaction to the received payoffs is studied. In general the existence and the magnitude of the asymptotic level of cooperation depends on N , the payoffs and the transition rates, and decreases with increasing N .