41 research outputs found
Data-Oblivious Graph Algorithms in Outsourced External Memory
Motivated by privacy preservation for outsourced data, data-oblivious
external memory is a computational framework where a client performs
computations on data stored at a semi-trusted server in a way that does not
reveal her data to the server. This approach facilitates collaboration and
reliability over traditional frameworks, and it provides privacy protection,
even though the server has full access to the data and he can monitor how it is
accessed by the client. The challenge is that even if data is encrypted, the
server can learn information based on the client data access pattern; hence,
access patterns must also be obfuscated. We investigate privacy-preserving
algorithms for outsourced external memory that are based on the use of
data-oblivious algorithms, that is, algorithms where each possible sequence of
data accesses is independent of the data values. We give new efficient
data-oblivious algorithms in the outsourced external memory model for a number
of fundamental graph problems. Our results include new data-oblivious
external-memory methods for constructing minimum spanning trees, performing
various traversals on rooted trees, answering least common ancestor queries on
trees, computing biconnected components, and forming open ear decompositions.
None of our algorithms make use of constant-time random oracles.Comment: 20 page
Theoretically Efficient Parallel Graph Algorithms Can Be Fast and Scalable
There has been significant recent interest in parallel graph processing due
to the need to quickly analyze the large graphs available today. Many graph
codes have been designed for distributed memory or external memory. However,
today even the largest publicly-available real-world graph (the Hyperlink Web
graph with over 3.5 billion vertices and 128 billion edges) can fit in the
memory of a single commodity multicore server. Nevertheless, most experimental
work in the literature report results on much smaller graphs, and the ones for
the Hyperlink graph use distributed or external memory. Therefore, it is
natural to ask whether we can efficiently solve a broad class of graph problems
on this graph in memory.
This paper shows that theoretically-efficient parallel graph algorithms can
scale to the largest publicly-available graphs using a single machine with a
terabyte of RAM, processing them in minutes. We give implementations of
theoretically-efficient parallel algorithms for 20 important graph problems. We
also present the optimizations and techniques that we used in our
implementations, which were crucial in enabling us to process these large
graphs quickly. We show that the running times of our implementations
outperform existing state-of-the-art implementations on the largest real-world
graphs. For many of the problems that we consider, this is the first time they
have been solved on graphs at this scale. We have made the implementations
developed in this work publicly-available as the Graph-Based Benchmark Suite
(GBBS).Comment: This is the full version of the paper appearing in the ACM Symposium
on Parallelism in Algorithms and Architectures (SPAA), 201
Managerial Views of Corporate Impacts and Dependencies on Ecosystem Services : A Case of International and Domestic Forestry Companies in China
A line of research is emerging investigating the private sector impacts and dependencies on critical biodiversity and ecosystem services, and related business risks and opportunities. While the ecosystem services narrative is being forwarded globally as a key paradigm for promoting business sustainability, there is scarce knowledge of how these issues are considered at managerial level. This study thus investigates managerial views of corporate sustainability after the ecosystem services concept. We analyse interviews conducted with 20 managers from domestic and international forestry companies operating with a plantation-based business model in China. Content analysis was employed to analyse the data, with a focus on four key areas: (1) interviewee familiarity with the ecosystem services concept; (2) their views of corporate dependencies and impacts on ecosystem services; (3) related business risks and opportunities; and (4) viability of existing instruments and practices that can be employed in detecting and addressing business impacts and dependencies on ecosystem services. Through an inductive approach to the empirical findings, we refined a framework that holds operational value for developing company response strategies to ecosystem services impact/dependence assessment, ensuring that all issues are addressed comprehensively, and that related risks and opportunities are properly acknowledged.Peer reviewe
The Role of Ethnic Directors in Corporate Social Responsibility: Does Culture matter? The Cultural Trait Theory Perspectives
This paper investigates the effect of cultural differences between ethnic directors on corporate social responsibility (CSR) of Public Liability Companies (PLCs) in Nigeria. Using the cultural trait theory, the study focuses on how the ethnic directors are influenced when making decisions concerning CSR. Adopting multiple regression analysis of data, the study investigates the three major ethnic groups (Yoruba, Igbo and Hausa) and finds cultural differences between the ethnic directors affect the adoption of CSR. Empirical results indicate that ethnic directors (Yoruba, Igbo and Hausa) were positively and significantly related to CSR. The paper contributes to the corporate governance and CSR debate concerning how ethnic directors’ decisions impact on CSR activities, particularly on the directors who are individualistic and collectivists towards CSR
FDI in hot labour markets: The implications of the war for talent
This paper highlights an inherent contradiction that exists within investment promotion activities in rich countries. Since the financial crisis, many inward investment agencies have shifted their activities from job creation per se to seeking to attract investment in high-tech activities. Such knowledge-intensive sectors are engaged in what has become referred to as “the war for talent”, so locations need to understand their value proposition to firms, especially where labour is tight. This paper explores the implications of this, in terms of the impact on employment and earnings of high skilled labour. We show that, because skill shortages already exist in many of these sectors, seeking to attract inward investment in these sectors simply causes the earnings of such workers to be bid up, and employment in the incumbent sector to fall. We highlight the over-riding importance that firms place on the availability of skilled labour when determining locations, and how policies which promote labour market flexibility, particularly through investment in skills to address skill shortages, can significantly mitigate the adverse effects, which tend to be more keenly felt in poorer regions of Europe where skilled labour is in even shorter supply
Reclaiming the child left behind: the case for corporate cultural responsibility
Although a reasonable understanding of corporate social responsibility (CSR) exists, one dimension remains largely ignored. That is, the cultural impacts of corporations, or the bearing, at various levels of their business models, activities, and outcomes on the value systems and enduring beliefs of affected people. We introduce the notion of corporate cultural responsibility (CCR). The way corporations address CCR concerns can be reflected according to three stances: cultural destructiveness, cultural carelessness, and cultural prowess. Taken sequentially, they reflect a growing comprehension and increasingly active consideration of CCR concerns by corporations. In turn, we explicitly address issues related to the complex question of determining the cultural responsibilities of corporate actors; specify key CCR-related conceptualizations; and lay a foundation for discussions, debates, and research efforts centered on CCR concerns and rationales
A simple undecidable problem: The inclusion problem for finite substitutions on ab*c
As an evidence of the power of finite unary substitutions we show that the inclusion problem for finite substitutions on the language L = ab*c i