Complex systems, be they natural or synthetic, are ubiquitous. In particular, complex networks of devices and services underpin most of society's operations. By their very nature, such systems are di cult to conceptualize and reason about e ectively. One seemingly natural notion, which helps to manage complexity and which is commonly found in discussions of complex systems, is that of layering: the system is considered to consist of a collection of interconnected layers that have distinct, identi able roles in the overall operations of the system. Noting that graphs are a key formalism in the description of complex systems, this thesis establishes a notion of a layered graph. A logical characterization of this notion of layering using a non-associative, non-commutative substructural, sepa- rating logic is provided. In addition, soundness and completeness results for a class of algebraic models that includes layered graphs are provided, which give a math- ematically substantial semantics to this very weak logic. Examples in information processing and security are used to show the applicability of the logic. The examples given use an informal notion of action. The thesis also presents a discussion of a number of possible languages that could be used to provide a dynamic extension of the logic. The key components of each language are identi ed and the semantics that would be required in the case of a full, theoretical, development are presented. Examples, mainly in access control, are used to illustrate situations where each extension could be applied. The logic is then used to describe a uniform logical framework for reasoning compositionally about access control policy models. The approach takes account of the underlying system architecture, and so provides a way to identify and reason about how vulnerabilities may arise (and be removed) as a result of the architecture of the system. The logic is then used to describe a uniform logical framework for reasoning compositionally about access control policy models. The approach takes account of the underlying system architecture, and so provides a way to identify and reason about how vulnerabilities may arise (and be removed) as a result of the architecture of the system. Using frame rules, it is also considered how local properties of access control policies are maintained as the system architecture evolves.

D.Econ.

M.Inf. / The Internet is a cost-effective and efficient way of distributing information to all stakeholders in a transparent, globalised business environment. It is imperative that companies adopt the Internet as a distribution method for corporate annual report information to remain competitive. The aim of this study was to determine the current state and level of adoption of the Internet as a delivery and communication mechanism for disseminating online/digital annual reports in the largest listed companies in South Africa. The population selected for the survey was the 2001 Financial Mail top 300 (SA Giants) companies based on total assets. The research was conducted by analysing the corporate websites of the selected companies. The survey was done to establish whether a corporate website existed and, if so, whether the full annual report was available and electronic format used. The aim of this study was to ascertain how many companies in South Africa are publishing full annual reports on the Web. The research consisted of a literature review and empirical study. The purpose of the literature review was to establish whether previous research exists in this field in South Africa. The results of the international literature review were compared to South Africa to determine whether the country is lagging behind global trends in this arena. The typical users, function, content and shortcomings of the annual report were identified. The benefits of and problems with digital annual reports for companies and stakeholders were described. Results indicate that the top 100 South African companies have increased their corporate Web presence from 43% in 1999 to 92% in 2002. Top 100 companies with annual reports on the Internet increased from 11% in 1999 to 84% in 2002. Results indicated that 227 (75,6%) of the top 300 companies had a website and 31 (10,3%) had no home page. The websites were also analysed to investigate how many companies had detailed electronic annual reports available. The study showed that 179 (59,6%) companies had digital annual reports and 48 (16,0%) had no digital annual report available on the Internet. Of the companies surveyed, 131 (43,6%) had their annual reports in PDF format and 58 (19,3%) in HTML. Only 38 companies (12,6%) presented annual reports in HTML and PDF format on the Internet. Very few companies provide users with the functionality to download data in spreadsheet format for manipulation. Only 7 companies (2,3%) offered this feature. This study also investigated the relationship between digital annual reports (dependent variable) and company characteristics (independent variable). The two independent variables chosen were profitability and industry type. The two dependent variables chosen were a corporate Web presence and digital annual reports. It can be concluded that there is a significant association between industry sector and digital annual reports, with 63,6% companies in the industrial sector with digital annual reports, compared to 82,1% in the financial sector and 77,4% in the mining resources sector. The conclusion can be drawn that there is no significant correlation between companies with a Web presence and the industry type in which each company operates. Of the companies in the industrial sector, 85,8% had Web presence compared to 92,3% in the financial sector and 90,3% in the mining resources sector. The investigation revealed that it is the profitable companies in South Africa with a corporate Web presence and with digital annual reports on their corporate websites.

by Leung Lee. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references. / Chapter SECTION 1. --- Introduction --- p.1 / Chapter SECTION 2. --- Formulation of Problem --- p.2 / Chapter 2.1 --- Problem Identification --- p.2 / Chapter 2.2 --- Network Planning Parameters and Assumptions --- p.3 / Chapter 2.3 --- Neural Network Model Transformation --- p.5 / Chapter 2.4 --- Algorithm and Implementation --- p.12 / Chapter SECTION 3. --- Simulation Results --- p.15 / Chapter 3.1 --- All Link Costs Are Same or Nearly the Same --- p.17 / Chapter 3.2 --- Fluctuated Cost in One or Two Fibre Paths --- p.18 / Chapter 3.3 --- Sudden Traffic Demand Change in Last Season --- p.19 / Chapter SECTION 4. --- Discussion --- p.20 / Chapter SECTION 5. --- Conclusion --- p.26 / GLOSSARY OF TERMS --- p.27 / BIBLIOGRAPHY --- p.29 / APPENDIX --- p.A1 / Chapter A --- Simulation Results --- p.A1 / Chapter B --- ANN Traffic Routing Example --- p.B1

by Wong, Chan-foon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 59-67 (1st gp.)). / Chapter Chapter I --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Traffic Characteristics --- p.2 / Chapter 1.3 --- Related Works --- p.5 / Chapter Chapter II --- Integrated Services Protocol (ISP) --- p.7 / Chapter 2.1 --- Ethernet --- p.7 / Chapter 2.2 --- ISP Description --- p.9 / Chapter 2.2.1 --- Voice Communications Characteristics --- p.9 / Chapter 2.2.2 --- Voice Packet Format --- p.12 / Chapter 2.2.3 --- Call Management --- p.13 / Chapter 2.4.4 --- Voice Packet Transmission Protocol --- p.14 / Chapter 2.4.5 --- Error Handling --- p.16 / Chapter Chapter III --- Protocol Studies --- p.17 / Chapter 3.1 --- Simulation Model And Parameters --- p.17 / Chapter 3.2 --- Voice Loss --- p.18 / Chapter 3.3 --- Data Delay --- p.20 / Chapter 3.4 --- Maximum Number Of Active Voice Stations --- p.22 / Chapter 3.5 --- Summary --- p.23 / Chapter Chapter IV --- Implementation --- p.24 / Chapter 4.1 --- System Platform --- p.24 / Chapter 4.2 --- Integrated Services Adapter (ISA) --- p.25 / Chapter 4.2.1 --- Hardware Design --- p.26 / Chapter 4.3 --- Voice on Ethernet Adapter (VEA) --- p.29 / Chapter 4.3.1 --- Hardware Design --- p.29 / Chapter 4.3.2 --- Software Design --- p.31 / Chapter 4.3.2.1 --- Programming The VEA --- p.32 / Chapter 4.3.2.2 --- Software Development Under DOS --- p.35 / Chapter 4.3.2.3 --- Software Development Under Linux --- p.37 / Chapter 4.4 --- Summary --- p.41 / Chapter Chapter V --- Implementation Results --- p.42 / Chapter 5.1 --- Frequency Response --- p.43 / Chapter 5.2 --- Distortion --- p.44 / Chapter 5.3 --- Amplification and Linearity --- p.45 / Chapter 5.4 --- Voice Quality With Different Voice Packet Sizes --- p.46 / Chapter 5.5 --- Voice Loss Under Various Data Loadings --- p.47 / Chapter Chapter VI --- Implementation Experiences --- p.49 / Chapter 6.1 --- CPU Bottle-neck --- p.49 / Chapter 6.2 --- Data Bus Bottle-neck --- p.50 / Chapter 6.3 --- Operating System --- p.50 / Chapter Chapter VII --- Future Works --- p.52 / Chapter 7.1 --- Enhancement of ISA --- p.52 / Chapter 7.2 --- Extensions To Other Networks --- p.53 / Chapter 7.3 --- A New Architecture For Future Multimedia Workstation --- p.54 / Chapter Chapter VIII --- Conclusions --- p.57 / Bibliography --- p.59 / Appendices --- p.A.l / Appendix A: Detailed Circuit Designs --- p.A.2 / Appendix B: Detailed Software Designs --- p.A.5 / Appendix C: Schematic Diagrams --- p.A.15 / Appendix D: Program Listings --- p.A.23

Wong, Ho Yin Starsky. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 81-85). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Problems of IP multicast --- p.2 / Chapter 1.3 --- End-system multicast --- p.3 / Chapter 1.4 --- The Challenge of ESM --- p.3 / Chapter 1.5 --- Document Roadmap --- p.4 / Chapter 2 --- System Architecture --- p.5 / Chapter 3 --- ESM Protocol --- p.8 / Chapter 3.1 --- ESM: Tree Formation Protocol --- p.8 / Chapter 3.1.1 --- Example of Tree Formation Protocol --- p.14 / Chapter 3.1.2 --- "The proof of ""Tree Formation Protocol always main- tains a tree topology""" --- p.15 / Chapter 3.1.3 --- "The proof of ""Tree Formation Protocol guarantees that there is no partition in the ESM-tree""" --- p.16 / Chapter 3.1.4 --- State Transition Diagram for Tree Formation Protocol --- p.16 / Chapter 3.2 --- ESM: Data Transfer --- p.28 / Chapter 3.3 --- ESM: Tree Optimization Protocol CONTENTS --- p.30 / Chapter 3.3.1 --- Example of Tree Optimization Protocol --- p.37 / Chapter 3.3.2 --- "The proof of ""Distributed Locking Protocol avoids loop formation and tree partition""" --- p.38 / Chapter 3.3.3 --- State Transition Diagram for Tree Optimization Protocol --- p.39 / Chapter 3.4 --- ESM: Node Leaving Protocol --- p.46 / Chapter 3.4.1 --- Example of ESM: Node Leaving Protocol --- p.51 / Chapter 3.4.2 --- State Transition Diagram for Node Leaving Protocol --- p.53 / Chapter 4 --- Performance Evaluation --- p.60 / Chapter 4.1 --- Experiment 1 - Comparisons between IP Unicast and ESM --- p.61 / Chapter 4.2 --- Experiment 2 - Comparisons between different ESM topologies --- p.64 / Chapter 4.3 --- Experiment 3 - Comparison between different thresholds for tree optimization operation --- p.67 / Chapter 4.4 --- Experiment 4 - NS2 Simulation --- p.69 / Chapter 5 --- Related Work --- p.74 / Chapter 6 --- Concluding Remarks --- p.78 / Chapter 6.1 --- Contributions --- p.78 / Chapter 6.2 --- Future Work --- p.79 / Chapter 6.2.1 --- Large-scale Experiments --- p.79 / Chapter 6.2.2 --- Evaluation for non-reliable data transfer --- p.79 / Chapter 6.2.3 --- Investigation of tree-optimization activation threshold --- p.80

by Lam Wan. / Thesis submitted in: November 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 96-102). / Abstract also in Chinese. / Part I / Chapter 1 --- Introduction to Integrated Intelligent Personal Communication System --- p.1 / Chapter 2 --- The Switching Architecture --- p.5 / Chapter 2.1 --- The Overall Switching Architecture --- p.6 / Chapter 2.2 --- Switching Module --- p.10 / Chapter 2.2.1 --- Traffic Routing in Switching Module --- p.11 / Chapter 2.2.2 --- Structure of Switching Module --- p.15 / Chapter 2.2.3 --- Wireless Base Interface --- p.16 / Chapter 2.2.4 --- Trunk Interface --- p.18 / Chapter 2.2.5 --- Analog Interfaces --- p.18 / Chapter 2.3 --- Network Intelligence --- p.19 / Chapter 2.4 --- Wireless Part --- p.21 / Chapter 2.4.1 --- Call-Setup in IIPCS --- p.24 / Chapter 2.4.2 --- Handoff --- p.25 / Chapter 2.4.3 --- Wireless Base --- p.27 / Chapter 2.5 --- Downstream Wired Extensions --- p.28 / Chapter 2.6 --- Upstream Wired Part --- p.28 / Chapter 2.7 --- Voice System --- p.28 / Chapter 2.8 --- Features of the IIPCS --- p.29 / Chapter 3 --- Concluding Remarks --- p.33 / Chapter 3.1 --- Summary --- p.35 / Chapter 3.2 --- Directions for Further Research --- p.36 / Part II / Chapter 4 --- Introduction to Next-Generation Switch --- p.37 / Chapter 5 --- Architecture of Next-Generation Switch --- p.41 / Chapter 5.1 --- Overall Architecture of Next-Generation Switch --- p.42 / Chapter 5.1.1 --- Interface module --- p.44 / Chapter 5.1.2 --- Packetizer --- p.46 / Chapter 5.2 --- Concentration Fabric --- p.50 / Chapter 5.3 --- Shared-Buffer Memory Switch --- p.53 / Chapter 6 --- Concentration Networks --- p.56 / Chapter 6.1 --- Background of Concentration Networks --- p.56 / Chapter 6.2 --- k-Sorting --- p.63 / Chapter 6.3 --- Concentrator --- p.72 / Chapter 6.3.1 --- Nk-to-k Concentrator --- p.73 / Chapter 6.3.2 --- Match between Circles with Cost Reduction --- p.75 / Chapter 6.4 --- The Structure of a Molecule --- p.78 / Chapter 6.5 --- Summary --- p.81 / Chapter 7 --- Lock-Latch Algorithm --- p.82 / Chapter 8 --- Performance Evaluation --- p.88 / Chapter 9 --- Concluding Remarks --- p.93 / Chapter 9.1 --- LSI Implementation --- p.94 / Chapter 9.2 --- Summary --- p.95 / Bibliography

近年來，標準化的媒體訪問控制（MAC）協議，在無線局域網（WLAN）和無線傳感器網絡（WSNs）中起著重要的作用。其中具有分佈式協調功能 (DCF) 的IEEE 802.11協議目前是一種最流行的WLAN標準，它包括MAC層和物理層的規範；而規範了PHY-MAC 的IEEE 802.15.4協議，也成為了促進部署各種商業用途的無線傳感器網絡的一個重要的里程碑。IEEE 802.11 DCF和802.15.4 MAC協議的核心是使用與防撞載波偵聽多路訪問協議 （CSMA/CA）。 / 雖然對這類MAC協議的研究已經持續了幾十年，但是研究者們仍然無法對這些無線網絡進行全面徹底的性能分析。 / 鑑於這種原因，我們在這篇論文中提出了一種通用馬爾可夫狀態空間模型，用於分析基於CSMA/ CA的MAC協議。每個節點的輸入緩衝器被模擬為一個Geo/G/1隊列，我們用了馬爾可夫鏈來描述每一個隊頭封包（HOL）的服務時間分佈。在本篇文章裡，這種馬爾可夫模型理論被運用於分析在非飽和條件下，基於概率指數補償的調度算法的兩種網絡：在理想信道和非理想信道條件下的IEEE 802.11 DCF網絡，以及IEEE 802.15.4網絡。 / 從這個排隊模型中，我們獲得了網絡穩態下吞吐量的特性方程，數據包平均分組接入延遲以及排隊延遲。此外，對於IEEE802.15.4網絡，通過馬爾可夫模型我們也得到每個節點的能量消耗的準確表達。 / 在這篇論文中，我們闡述了對於MAC網絡的吞吐量和排隊延遲方面的穩定條件。基於這兩個穩定條件，我們能夠得出兩種區域：穩定的吞吐量區域和有界延遲區域，並發現它們與補償調度算法和總輸入量有著密切的關係。另外我們證明了這種指數補償演算法同樣適合龐大用戶量的網絡。 / 對於802.11 DCF網絡，我們發現基於RTS / CTS訪問機制的網絡性能受到總輸入量和轉播因子的影響比基於基本訪問機制的網絡來的小。此外，經過對比理想和非理想信道下網絡性能的表現，我們發現傳輸錯誤對網絡的吞吐量和延遲也會產生重大影響。對於IEEE802.15.4網絡，我們的研究結果證實在穩定的吞吐區域內，單個節點的能耗較少。 / 最後，我們將這種方法擴展到基於競爭窗口補償模型中，對比分析證明了概率補償演算法的模型可以有效地用於分析實際中基於競爭窗口機制的無線網絡。 / In recent years, the standardized Media Access Control (MAC) protocol plays an important role in wireless local area networks (WLANs) and wireless sensor networks (WSNs). The IEEE 802.11 protocol with distributed coordination function (DCF) is the most popular standard in WLANs that includes specifications for both MAC and physical layers, whereas the IEEE 802.15.4 PHY-MAC specifications represents a significant milestone in promoting deployment of WSNs for a variety of commercial uses. The core of the 802.11 DCF and 802.15.4 MAC protocols is the Carrier-Sense Multiple-Access protocol with Collision Avoidance (CSMA/CA). / Although the studies of such kinds of MAC protocols have been lasted for several decades, a thorough network performance analysis of these wireless networks still cannot be tackled in the existing works. / In light of this concern, we propose a generic Markov state space model of the MAC protocols with CSMA/CA for contention resolution in this thesis. The input buffer of each node is modeled as a Geo/G/1 queue, and the service time distribution is derived from a Markov chain describing the state transitions of head-of-line (HOL) packets. This Markov model is well demonstrated by the IEEE 802.11 DCF networks in either ideal channels or imperfect channels, and IEEE 802.15.4 networks, with probabilistic exponential backoff scheduling algorithm under non-saturated condition. / With this queueing model, we obtain the steady state characteristic equation of network throughput as well as the mean packet access and queueing delays of packets. Moreover, for the IEEE 802.15.4 networks, the accurate expressions of energy consumptions for each node can also be obtained through this Markov model. / In this dissertation, we specify the stability conditions in terms of throughput and queueing delay for MAC networks. These two stable conditions enable us to derive two kinds of regions: the stable throughput region and the bounded delay region, which is dependent on the backoff scheduling algorithm and the aggregate input traffic. We prove that the stable regions still exist even for an infinite population with exponential backoff. / For the IEEE 802.11 DCF networks, it depicts that the network performance of RTS/CTS access scheme is less dependent on the aggregate input rate and retransmission factor than that of the Basic access mechanism. Additionally, with the comparison of the networks performance under ideal and imperfect channels, we also show that the transmission errors have a significant impact on both throughput and delay of networks. For the IEEE 802.15.4 networks, our results confirm that the energy consumption of a single node is kept small within its stable throughput region. / Last but not least, we extend our approach to the contention-window-based backoff model, and depict that the probabilistic backoff model can serve as a good analytical model for the practical contention window mechanism. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Yin, Dongjie. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 151-160). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Chapter Chapter 1 --- Introduction of IEEE Standard MAC Protocols --- p.1 / Chapter 1.1 --- Medium Access Control (MAC) Protocols --- p.2 / Chapter 1.1.1 --- Medium access control in wireless LANs --- p.3 / Chapter 1.1.2 --- Medium access control in wireless sensor networks --- p.6 / Chapter 1.2 --- Backoff Scheduling Algorithms for Contention Resolution --- p.8 / Chapter 1.3 --- Our Methodologies --- p.11 / Chapter 1.3.1 --- Multi-queue-singer-server system --- p.11 / Chapter 1.3.2 --- State space of Markov chain for MAC protocols --- p.15 / Chapter 1.4 --- Contributions --- p.19 / Chapter 1.4.1 --- The Markov state space model of MAC protocols --- p.20 / Chapter 1.4.2 --- Stability analysis of networks --- p.20 / Chapter 1.4.3 --- Probabilistic exponential backoff and window-based exponential backoff --- p.21 / Chapter 1.5 --- Dissertation Overview --- p.22 / Chapter Chapter 2 --- IEEE 802.11 Distributed Coordination Function --- p.24 / Chapter 2.1 --- Introduction and Overview of IEEE 802.11 DCF --- p.25 / Chapter 2.1.1 --- Principle of IEEE 802.11 DCF protocols --- p.25 / Chapter 2.1.2 --- Historical background of IEEE 802.11 DCF --- p.26 / Chapter 2.1.3 --- Contributions of our works --- p.29 / Chapter 2.2 --- Queuing Model of HOL Packet for the 802.11 DCF --- p.31 / Chapter 2.2.1 --- Alternating renewal process of channel --- p.31 / Chapter 2.2.2 --- Queuing model of input buffer --- p.34 / Chapter 2.3 --- Stable Throughput Region for the 802.11 DCF --- p.42 / Chapter 2.3.1 --- Stable throughput condition --- p.43 / Chapter 2.3.2 --- Stable throughput region of exponential backoff --- p.45 / Chapter 2.4 --- Bounded Delay Region for IEEE 802.11 --- p.52 / Chapter 2.4.1 --- Bounded delay condition --- p.52 / Chapter 2.4.2 --- Bounded delay region of exponential backoff --- p.53 / Chapter 2.5 --- Window-based Exponential Backoff --- p.57 / Chapter 2.6 --- Conclusion --- p.63 / Chapter Chapter 3 --- IEEE 802.11 DCF in Presence of Non-Ideal Transmission Channel --- p.65 / Chapter 3.1 --- Introduction of IEEE 802.11 DCF with Error-Prone --- p.66 / Chapter 3.1.1 --- Collision and error control in 802.11 DCF --- p.66 / Chapter 3.1.2 --- Historical background --- p.69 / Chapter 3.2 --- Queuing Model of Input Buffer for the 802.11 DCF with Error-Prone Channels --- p.71 / Chapter 3.3 --- Stability Analysis --- p.83 / Chapter 3.3.1 --- Stability analysis of network throughput --- p.83 / Chapter 3.3.2 --- Stability analysis of queueing delay --- p.91 / Chapter 3.4 --- Conclusion --- p.96 / Chapter Chapter 4 --- Performance Analysis of IEEE 802.15.4 Beacon-Enabled Mode --- p.97 / Chapter 4.1 --- Introduction --- p.98 / Chapter 4.1.1 --- Principle of IEEE 802.15.4 protocols --- p.98 / Chapter 4.1.2 --- Historical background of IEEE 802.15.4 --- p.101 / Chapter 4.1.3 --- Contributions of our works --- p.103 / Chapter 4.2 --- Queuing Model of Input Buffer for IEEE 802.15.4 --- p.105 / Chapter 4.2.1 --- Queuing model of input buffer --- p.106 / Chapter 4.2.2 --- Stable conditions of exponential backoff --- p.113 / Chapter 4.3 --- Analysis of Uplink Traffic without Acknowledgement --- p.116 / Chapter 4.4 --- Analysis of Acknowledged Uplink Traffic --- p.122 / Chapter 4.5 --- Analysis of Power Consumption of Each Node --- p.127 / Chapter 4.5.1 --- Power consumption of non-acknowledgement mode --- p.129 / Chapter 4.5.2 --- Power consumption of acknowledgement mode --- p.130 / Chapter 4.6 --- Simulation and Numerical Results --- p.132 / Chapter 4.7 --- Conclusion --- p.137 / Chapter Chapter 5 --- Summary and Future Works --- p.139 / Chapter 5.1 --- Contribution Summary --- p.140 / Chapter 5.2 --- Future Works --- p.142 / Chapter Appendix A --- Service Time Distribution for the Ideal 802.11 DCF with Exponential Backoff --- p.145 / Chapter Appendix B --- Throughput of802.11 DCF with Window-Based Backoff Scheme --- p.146 / Chapter Appendix C --- Service Time Distribution for the 802.11 DCF under Error-Prone Channels with Exponential Backoff --- p.147 / Chapter Appendix D --- Service Time Distribution for the IEEE 802.15.4 with Exponential Backoff --- p.150 / Bibliography --- p.151

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