New strongly regular graphs from finite geometries via switching

We show that the strongly regular graph on non-isotropic points of one type of the polar spaces of type U(n, 2), O(n, 3), O(n, 5), O+ (n, 3), and O- (n, 3) are not determined by its parameters for n >= 6. We prove this by using a variation of Godsil-McKay switching recently described by Wang, Qiu, and Hu. This also results in a new, shorter proof of a previous result of the first author which showed that the collinearity graph of a polar space is not determined by its spectrum. The same switching gives a linear algebra explanation for the construction of a large number of non-isomorphic designs. (C) 2019 Elsevier Inc. All rights reserved

New Strongly Regular Graphs from Finite Geometries via Switching

We show that the strongly regular graph on non-isotropic points of one type of the polar spaces of type $U(n, 2)$, $O(n, 3)$, $O(n, 5)$, $O^+(n, 3)$, and $O^-(n, 3)$ are not determined by its parameters for $n \geq 6$. We prove this by using a variation of Godsil-McKay switching recently described by Wang, Qiu, and Hu. This also results in a new, shorter proof of a previous result of the first author which showed that the collinearity graph of a polar space is not determined by its spectrum. The same switching gives a linear algebra explanation for the construction of a large number of non-isomorphic designs.Comment: 13 pages, accepted in Linear Algebra and Its Application

Why Blu-ray vs. HD-DVD is not VHS vs. Betamax: The co-evolution of standard-setting consortia

Extensive research has been conducted on the economics of standards in the last three decades. To date, standard-setting studies emphasize a superior role of demand-side-driven technology diffusion; these contributions assume the evolution of a user-driven momentum and network externalities. We find that consumers wait for a dominant standard if they are unable to evaluate technological supremacy. Thus, supply-side driven activities necessarily need to address a lacking demand-side technology adoption. Our paper focuses on Blu-ray vs. HD-DVD as an illustrative case of consortia standard wars. One central role of consortia is to coordinate strategic behavior between heterogeneous agents, e.g. incumbents, complementors (content providers) and others, but also to form a coalition against other standard candidates. More precisely, we argue for signalizing activities through consortia events. We depict the essential role of consortia structures for the recently determined standard war between the High-Definition disc specifications Blu-ray and HD-DVD. Therefore, the paper suggests that unique supply-side dynamics from consortia structures, consortia announcements and exclusive backing decisions of firms determined the standard-setting process in the Blu-ray vs. HD-DVD standard war. This study is based on the following data: movie releases and sales numbers, membership affiliation for structural consortia analysis, and an in-depth event study. A detailed comparison of the technological specifications of both standard specifications supports our argument that there was no technological supremacy of one standard candidate from a consumer-oriented usecase perspective. We furthermore clarify that content providers (complementors) such as movie studios and movie rental services feature a gate-keeping position in the Blu-ray vs. HD-DVD standard war. In the case of Blu-ray, film studios decided the standard war because the availability of movie releases, but not technological supremacy, made the standard attractive to consumers. Finally, we find that there is a co-evolution of the consortia in terms of membership dynamics. Particularly, firm allegiance of heterogeneous agents plays a crucial role. --Blu-ray,HD-DVD,standard wars,co-evolution,consortia,event study

Why blu-ray vs. HD-DVD ist not VHS vs. Betamax: the co-evolution of standard-setting consortia

Extensive research has been conducted on the economics of standards in the last three decades. To date, standard-setting studies emphasize a superior role of demand-side-driven technology diffusion; these contributions assume the evolution of a user-driven momentum and network externalities. We find that consumers wait for a dominant standard if they are unable to evaluate technological supremacy. Thus, supply-side-driven activities necessarily need to address an absence of demand-side technology adoption. Our paper focuses on Blu-ray vs. HD-DVD as an illustrative case of consortia standard wars. One central role of consortia is to coordinate strategic behavior between heterogeneous agents, e.g. incumbents, complementors (content providers) and others, but also to form a coalition against other standard candidates. More precisely, we argue that agents signal standard-setting war outcomes through consortia events. We depict the essential role of consortia structures for the recently determined standard war between the High-Definition disc specifications Blu-ray and HD-DVD. Therefore, the paper suggests that unique supply-side dynamics from consortia structures, consortia announcements and exclusive backing decisions of firms determined the standard-setting process in the Blu-ray vs. HD-DVD standard war. This study is based on the following data: movie releases and sales numbers, membership affiliation for structural consortia analysis, and an in-depth event study. A detailed comparison of the technological specifications of both standard specifications supports our argument that there was no technological supremacy of one standard candidate from a consumer-oriented usecase perspective. We furthermore clarify that content providers (complementors) such as movie studios and movie rental services feature a gate-keeping position in the Blu-ray vs. HD-DVD standard war. In the case of Blu-ray, film studios decided the standard war because the availability of movie releases, but not technological supremacy, made the standard attractive to consumers. Finally, we find that there is a co-evolution of the consortia in terms of membership dynamics. Particularly, firm allegiance of heterogeneous agents plays a crucial role. --Blu-ray,HD-DVD,standard wars,co-evolution,consortia,event study

Diagnose network failures via data-plane analysis

Diagnosing problems in networks is a time-consuming and error-prone process. Previous tools to assist operators primarily focus on analyzing control plane configuration. Configuration analysis is limited in that it cannot find bugs in router software, and is harder to generalize across protocols since it must model complex configuration languages and dynamic protocol behavior. This paper studies an alternate approach: diagnosing problems through static analysis of the data plane. This approach can catch bugs that are invisible at the level of configuration files, and simplifies unified analysis of a network across many protocols and implementations. We present Anteater, a tool for checking invariants in the data plane. Anteater translates high-level network invariants into boolean satisfiability problems, checks them against network state using a SAT solver, and reports counterexamples if violations have been found. Applied to a large campus network, Anteater revealed 23 bugs, including forwarding loops and stale ACL rules, with only five false positives. Nine of these faults are being fixed by campus network operators

Mixing multi-core CPUs and GPUs for scientific simulation software

Recent technological and economic developments have led to widespread availability of multi-core CPUs and specialist accelerator processors such as graphical processing units (GPUs). The accelerated computational performance possible from these devices can be very high for some applications paradigms. Software languages and systems such as NVIDIA's CUDA and Khronos consortium's open compute language (OpenCL) support a number of individual parallel application programming paradigms. To scale up the performance of some complex systems simulations, a hybrid of multi-core CPUs for coarse-grained parallelism and very many core GPUs for data parallelism is necessary. We describe our use of hybrid applica- tions using threading approaches and multi-core CPUs to control independent GPU devices. We present speed-up data and discuss multi-threading software issues for the applications level programmer and o er some suggested areas for language development and integration between coarse-grained and ne-grained multi-thread systems. We discuss results from three common simulation algorithmic areas including: partial di erential equations; graph cluster metric calculations and random number generation. We report on programming experiences and selected performance for these algorithms on: single and multiple GPUs; multi-core CPUs; a CellBE; and using OpenCL. We discuss programmer usability issues and the outlook and trends in multi-core programming for scienti c applications developers

Standards, IPR and digital TV convergence: theories and empirical evidence

none1Media convergence presents a few noticeable dimensions, and requests an interdisciplinary research approach. We conduct a long-run analysis of the main initiatives of technological standardization carried out in the realm of “traditional” (cable, satellite and terrestrial) digital TV, focusing on Europe, to assess the technological determinants of its apparent trends to convergence. This analysis inevitably calls into question IPR strategies and policies. In particular, we investigate how private incentives and the public agenda for interoperability have shaped the on-going convergence of the TV sector toward an “IP-based” meta-platform. Despite the widespread usage of open standards and formats, the real potential for interoperability along the digital TV filière has been modest, and mostly limited to the transmission segment. This is mainly due to the strong proprietary features characterizing the TV sector, where viable content production and provision rests on effective control of content IPR. Further, patent portfolio strategies and control of crucial copyrights become increasingly central for competing in the converging TV sector, where former telecom companies, traditional TV operators and new OTT players strive to become gatekeepers of essential layers of the new IP-based delivery platforms. To sum up, while technological opportunities today do enable pervasive media interoperability and affordable convergence at the user-level, private incentives relentlessly push the industry toward standards fragmentation and the construction of walled gardens.MPRA Working paper series n. 59359, Munich Personal RePEc ArchiveMatteucci NMatteucci, Nicol