Our friends have more friends than we do. That is the basis of the friendship paradox. In mathematical terms, the mean number of friends of friends is higher than the mean number of friends. In the present study, we analyzed the relationship between the mean degree of vertices (individuals), 〈k〉, and the mean number of friends of friends, 〈kFF 〉, in scale-free networks with degrees ranging from...

Philanthropic decision-making is important both for its potential to provide insight into human behaviour and for its economic significance. In recent years, investigations of charitable-giving behaviour have expanded substantially, including explorations from a variety of disciplinary perspectives such as economics, marketing, sociology, public administration, anthropology, evolutionary biolog...

a r t i c l e i n f o To explain the high level of altruism among unrelated friends, some people propose that friends may apply the feeling and emotions that underlie kin-selected nepotism to each other. Alternatively, altruism among friends may be sustained by an evolved psychology that is sensitive to the dynamic of contingent reciprocity. A recent study (Stewart-Williams, S., 2007. Altruism ...

We conduct field experiments in a large real-world social network to examine why decision makers treat friends more generously than strangers. Subjects are asked to divide surplus between themselves and named partners at various social distances, where only one of the decisions is implemented. In order to separate altruistic and future interaction motives, we implement an anonymous treatment wh...

Friendship is a fundamental characteristic of human beings and usually assumed to be reciprocal in nature. Despite this common expectation, in reality, not all friendships by default are reciprocal nor created equal. Here, we show that reciprocated friendships are more intimate and they are substantially different from those that are not. We examine the role of reciprocal ties in inducing more ...

In this paper we provide a purely combinatorial proof of the Friendship Theorem, which has been first proven by P. Erdös et al. by using also algebraic methods. Moreover, we generalize this theorem in a natural way, assuming that every pair of nodes occupies ≥ 2 common neighbors. We prove that every graph, which satisfies this generalized -friendship condition, is a regular graph.

Abstract This article examines gift-giving within the Persian empire and its perception in Greek literary sources. Gift-giving world was often framed language of friendship, authors subsequently articulated traditions using cultural norms their intended audience. There were fundamental differences concepts gift-exchange reciprocity between Greeks Persians. will examine followed by gift-giving, ...

n 1991 sociologist Scott Feld wrote a scientific paper entitled “Why your friends have more friends than you do.”1 Strange title for a paper, particularly because most of us do not perceive ourselves as any less popular than our friends. But according to Feld, if we could count the number of friends our friends have, most of us would find we come up short. Indeed, in any social group it can be ...

Gangs and group-level processes were once central phenomena for criminological theory and research. By the mid-1970's, however, gang research was primarily displaced by studies of individual behavior using randomized self-report surveys, a shift that also removed groups from the theoretical foreground. In this project, we return to the group level to test competing theoretical claims about deli...

The capacity to collect fingerprints of individuals in online media has revolutionized the way researchers explore human society. Social systems can be seen as a nonlinear superposition of a multitude of complex social networks, where nodes represent individuals and links capture a variety of different social relations. Much emphasis has been put on the network topology of social interactions, ...