Informational Cascades: A Mirage?

Experimental research found contradictory results regarding the occurrence of informational cascades. Whereas Anderson and Holt (1997) confirmed the model of Banerjee (1992), and Bikhchandani et al. (1992) through lab tests, Huck and Oechssler (2000) came to contradictory results on crucial issues. This article presents experimental evidence supporting further doubts concerning "Bayesian" informational cascades: Just under two thirds of all decisions are characterized by an excessive orientation towards the private signal, and only a small number of the subjects (<6%) make rational decisions systematically and consistently

Graph Concatenation for Quantum Codes

Graphs are closely related to quantum error-correcting codes: every stabilizer code is locally equivalent to a graph code, and every codeword stabilized code can be described by a graph and a classical code. For the construction of good quantum codes of relatively large block length, concatenated quantum codes and their generalizations play an important role. We develop a systematic method for constructing concatenated quantum codes based on "graph concatenation", where graphs representing the inner and outer codes are concatenated via a simple graph operation called "generalized local complementation." Our method applies to both binary and non-binary concatenated quantum codes as well as their generalizations.Comment: 26 pages, 12 figures. Figures of concatenated [[5,1,3]] and [[7,1,3]] are added. Submitted to JM

Leveraging Big Data for M&A: Towards Designing Process Mining Analyses for Process Assessment in IT Due Diligence

The success of mergers & acquisitions (M&A) depends on the buyer\u27s adequate due diligence (DD) assessment of the target firm. Assessing the target\u27s IT-enabled processes recently emerged as a novel information technology DD (IT DD) responsibility. However, it remains unclear how to operationalize and conduct the process assessment in IT DD. To address this challenge, we propose the big data analytics technology process mining (PM) and follow a design science research approach, based on literature and 12 interviews, to reveal and operationalize requirements for process assessment in IT DD, demonstrate PM to measure the operationalized requirements, and derive design principles and enabling factors to guide the design, implementation, and use of PM for process assessment in IT DD. Consequently, our study contributes to research on IT DD, M&A, and PM and provides practitioners with design knowledge and a prototypical PM artifact to leverage PM for process assessment in IT DD

Optimal construction of k-nearest neighbor graphs for identifying noisy clusters

We study clustering algorithms based on neighborhood graphs on a random sample of data points. The question we ask is how such a graph should be constructed in order to obtain optimal clustering results. Which type of neighborhood graph should one choose, mutual k-nearest neighbor or symmetric k-nearest neighbor? What is the optimal parameter k? In our setting, clusters are defined as connected components of the t-level set of the underlying probability distribution. Clusters are said to be identified in the neighborhood graph if connected components in the graph correspond to the true underlying clusters. Using techniques from random geometric graph theory, we prove bounds on the probability that clusters are identified successfully, both in a noise-free and in a noisy setting. Those bounds lead to several conclusions. First, k has to be chosen surprisingly high (rather of the order n than of the order log n) to maximize the probability of cluster identification. Secondly, the major difference between the mutual and the symmetric k-nearest neighbor graph occurs when one attempts to detect the most significant cluster only.Comment: 31 pages, 2 figure

Innovative method for cutting edge preparation with flexible diamond tools

The micro geometry of the cutting edge is of central importance for the performance of cutting tools. It influences all essential parameters in the machining process: chip formation, thermal and mechanical load on the tool and the workpiece, tool wear and the resulting workpiece quality. The effect depends on the size and shape of the cutting edge rounding. Depending on the machining process, asymmetrical roundings often show the greatest potential. In addition to increasing tool life, the quality of the surfaces produced can be improved by a specifically designed asymmetrical rounding. For edge preparation, blasting, brushing and drag finishing are used in industrial applications. However, an economic production of asymmetrical cutting edge geometries on cutting tools with complicated cutting edge geometry, such as solid carbide tools with helical cutting edge, cannot be achieved with these methods. Therefore, a novel method for preparation of the cutting edge rounding using flexible bond diamond polishing tools is introduced. Hence, the conducted research in this study analyzes the basic mechanisms and influencing factors using the new preparation method. For this purpose, polishing tests are carried out on carbide indexable inserts. The results show that the polishing tools can be used to create both asymmetrical and symmetrical roundings in an industrially relevant dimension. © 2019 The Authors. Published by Elsevier B.V

User Roles on Peer-to-Peer Sharing Platforms: A Critical Review of the Literature and Recommended Remedies

The success of sharing platforms such as Airbnb and Uber sparked interests in research, practice, and legislation in equal measures. However, studies about user roles on sharing platforms are very heterogeneous and have yet not dived into the theoretical complexity of these roles. In order to prevent incomparability of results and scattered theory building, this study reviews existing literature and identifies flaws in terminology and conceptualization of user roles and in applied measurement approaches. We discuss why these flaws matter and how they can be resolved. Finally, we propose a research agenda and emphasize to study the role of the prosumer, why different user roles lead to differences in constructs, and how the transition of user roles takes place

Analysis of profile and flatness in flat hot rolling based on non linearly coupled models for elastic roll stack deflection and pseudo-steady-state elasto-viscoplastic strip

An enhanced iterative concept for the effective numerical simulation of flat hot rolling processes is presented. The underlying physical process is the forming of metal within a flat rolling stand, i.e. between a lower and an upper roll set, each of them consisting of one or more rolls. The strip material is described elasto-viscoplastically, whereas the roll stack is deformed elastically. The accurate coupling of the strip model with the routines for the elastic roll stack deflection is a precondition to get reliable results concerning profile transfer and incompatible residual strains inside the strip, which allows the prediction of flatness defects, such as buckling. Especially for thin, wide strips and heavy plates, where the aspect ratio width over thickness is extremely unfavourable, the determination of profile transfer and flatness bviously leads to extremely high calculation times with commercial FEM-programs. Therefore, a tailor-made FEM-code for the efficient simulation of the elasto-viscoplastic material flow inside the roll gap was developed and programmed in C++. It is based on pseudo-steady-state, fully implicit stress-update approaches, where the incremental material objectivity is satisfied exactly. The developed model is well suited for systematic parameter studies to investigate flatness defects in more detail and to develop enhanced flatness criteria for thin hot and cold strips and plates

Rationales Herdenverhalten bei US-amerikanischen Rentenmarkt-Analysten: Verhaltensabstimmung durch ein externes Signal

"Experimental research found contradictory results regarding the occurrence of informational cascades. Whereas Anderson and Holt (1997) confirmed the model of Banerjee (1992), and Bikhchandani, Hirshleifer, and Welch (1992) through lab tests, Huck and Oechssler 2000) came to controversial results for crucial issues. This study is an extensive (227 test persons) - and as regards contents - expanded repetition. In conclusion, less than 10% of subjects are able to make deductions about predecessors’ private signals from their actions, to consider the reliability of the signals and the a priori probability, to accurately use Bayes’ Rule, and to thus reach rational decisions." (author's abstract