A guarantee is only as good as its assumptions. Three group membership areas defy firm, practical guarantees: transient faults, reintegration, and large groups. We show why these areas are problematic, discuss current approaches, and illustrate alternative approaches that may lead to a more dependable system. Ultimately, designs should be tested against a comprehensive fault model, and a probab...

In this paper, we measure and model the distribution of multicast group members. Multicast research has traditionally been plagued by a lack of real data and an absence of a systematic simulation methodology. Although temporal group properties have received some attention, the location of group members has not been measured and modelled. However, the placement of members can have significant im...

Today’s large-scale services generally exploit looselycoupled architectures that restrict functionality requiring tight cooperation (e.g., leader election, synchronization, and reconfiguration) to a small subset of nodes. In contrast, this work presents a way to scalably deploy tightlycoupled distributed systems that require significant coordination among a large number of nodes in the wide are...

We present a specification for a new, localized group membership service that maintains the membership status of adjacent nodes – called neighbors – in a mobile distributed system. The service builds on top of a neighborhood service which employs a simple heartbeat mechanism to discover and track neighbors in the mobile network. Both services assume unreliable communication as found in the wire...

BACKGROUND In ecologic studies, group-level rather than individual-level exposure data are used. When using group-level exposure data, established by sufficiently large samples of individual exposure assessments, the bias of the effect estimate due to sampling errors or random assessment errors at the individual-level is generally negligible. In contrast, systematic assessment errors may produc...

Recent theoretical work has highlighted potential links between interpersonal collaboration and group membership in the evolution of human sociality. Here we compared the effects of collaboration and minimal-group membership on young children's prosocial behavior (i.e., helping and resource allocation), liking, affiliation, and trust. In a design that matched as closely as possible these two wa...

We show that the membership problem in a finitely generated submonoid of a graph group (also called a right-angled Artin group or a free partially commutative group) is decidable if and only if the independence graph (commutation graph) is a transitive forest. As a consequence we obtain the first example of a finitely presented group with a decidable generalized word problem that does not have ...

This study analyzes the effects of group membership change on group cognition and performance to determine how groups can simultaneously leverage oldtimers’ collective knowledge and a newcomer’s expertise. Our analysis focuses specifically on the interrelated effects of the two components of a transactive memory system (TMS)—TMS structure and TMS processes—to explain the cognitive mechanisms th...

According to the characteristics of waterway navigation safe routes selection, and considering individual feelings group benefits information, as well no-compensation information between indexes, this paper describes rating routes, then puts forward an evaluation model method for route selection based on variable weight VIKOR. First all, from concept connotation grade assessment, so avoid confu...