Hierarchical data structures in variationist linguistics are given when, for
example, each of a number of speakers makes several utterances of interest
and individual observations are therefore not independent. Structures of this
kind are often not fully reflected in the analytic tools used to model language
variation. Against this background, the paper investigates the presence or
absence of coda-/r/ in a hierarchically structured dataset produced by 27
middle-class speakers of Scottish Standard English (SSE). Two regressionbased
statistical techniques are compared: multiple logistic regression and a
hierarchical generalized linear model (HGLM). The latter emerges as a
model that is not only more correct in theoretical terms because it takes the
nested structure of the data into account, but also detects cross-level effects
that go unnoticed in multiple logistic regression. The most striking finding
is, for example, that in prepausal position coda-/r/ is less likely to be deleted,
an effect, however, that is not general but depends critically upon the age of
the speaker and the dialect contact to which he or she has been exposed. The
paper thus provides one example of the potential of HGLM to explain
complex patterns of variation in hierarchically structured data.
Interface theories are employed in the component-based design of concurrent systems. They often emerge as combinations of Interface Automata (IA) and Modal Transition Systems (MTS), e.g., Nyman et al.’s IOMTS, Bauer et al.’s MIO, Raclet et al.’s MI or our MIA. In this paper, we generalise MI to nondeterministic interfaces, for which we resolve the longstanding conflict between unspecified inputs being allowed in IA but forbidden in MTS. With this solution we achieve, in contrast to related work, an associative parallel composition, a compositional preorder, a conjunction on interfaces with dissimilar alphabets supporting perspective-based specifications, and a quotienting operator for decomposing nondeterministic specifications in a single theory.
Today, process-aware systems are ubiquitous. They are built by leveraging process languages for both business and implementation perspectives. In the typical context of a Web Services-based Service-oriented Architecture, the obvious choice to implement service orchestrations is still the Business Process Execution Language (BPEL). For BPEL, a variety of open source and commercial engines have emerged. Although the BPEL standard document defines a set of static analysis rules which should be checked by engines prior to deployment to be standard conformant, previous work revealed that most engines are not capable of revealing all violations of these constraints, resulting in costly runtime errors later on. In this paper, we aim to improve the static analysis conformance of BPEL engines. We implement the tool BPELlint that validates 71 static analysis rules of the BPEL specification, show that the tool can be easily integrated into the deployment process of existing engines, and evaluate its performance to measure the effect on the time to deploy. The results demonstrate that BPELlint can improve the static analysis conformance of BPEL engines with an acceptable performance overhead.
Service-oriented systems are increasingly implemented in a process-based fashion. Multiple languages for building process-based systems are available today, but the Business Process Model and Notation (BPMN) is becoming ubiquitous. With BPMN 2.0 released in 2011, execution semantics were introduced, supporting the definition of executable processes. Nowadays, more and more process engines directly support the execution of BPMN processes. However, the BPMN specification is lengthy and complex. As there are no official tests and no certification authority, it is very likely that engines a) implement only a subset of the language features and b) implement language features differently. In other words, we suspect that engines do not conform to the standard, despite the fact that they claim support for it. This prohibits the porting of processes between different BPMN vendors, which is an acclaimed goal of the language. In this paper, we investigate the standard conformance of open source BPMN engines to provide a clear picture of the current state of the implementation of BPMN. We develop a testing approach that allows us to build fully BPMN-compliant tests and automatically execute these tests on different engines. The results demonstrate that state of-the-art BPMN engines only support a subset of the language. Moreover, they indicate that porting BPMN processes is only feasible when using basic language constructs.
The crowdfunding phenomenon has garnered a considerable amount of attention in recent years. Several online crowdfunding platforms have risen to prominence; they can be characterized as two-sided marketplaces. Recent research reveals initial insights into the dynamics and characteristics of crowdfunding networks arising from such marketplaces. This research, though, is restricted primarily to analyses of static network snapshots and at the dyadic level. In this study, we use a large longitudinal dataset to analyze the behavior of actors on both sides of the market who promote their own and fund others’ projects. We investigate the influence of endogenous and exogenous effects on the dynamics of crowdfunding networks. Our results provide evidence for mechanisms promoting a hierarchical network organization and the absence of homophily-related mechanisms regarding gender or geographic distance. Moreover, we establish that experienced and popular project creators fund fewer projects.
Organizations increasingly rely on group-based organizational structures to manage uncertain environments. However, at the group level there is still a limited understanding of how boundary-spanning activities should be managed to increase group performance. In this paper, we propose "out-group-tie centralization" as a concept that refers to the variation in the group members' network ties to other social actors who are not members of the group itself. When the out-group-tie centralization is low, no group member enjoys substantially more ties to other social actors outside the group than does any other group member. A panel analysis with 120 work groups from a medium-size German bank over a 12-month period reveals a reversed u-shaped relationship between out-group-tie centralization and group performance. However, the results indicate no association between the density of a work group communication network and that group's performance.