Even Simple Processes of Pi-calculus are Hard for Analysis
Mathematical models of distributed computations, based on the calculus of mobile processes (pi-calculus) are widely used for checking the information security properties of cryptographic protocols. Since pi-calculus is Turing-complete, this problem is undecidable in general case. Therefore, the study is carried out only for some special classes of pi-calculus processes with restricted computational capabilities, for example, for non-recursive processes, in which all runs have a bounded length, for processes with a bounded number of parallel components, etc. However, even in these cases, the proposed checking procedures are time consuming. We assume that this is due to the very nature of the pi -calculus processes. The goal of this paper is to show that even for the weakest model of passive adversary and for relatively simple protocols that use only the basic pi-calculus operations, the task of checking the information security properties of these protocols is co-NP-complete.
The Asia-Pacific Economic Cooperation forum (APEC) is one of the key platforms of the multilateral dialogue on global agenda issues in the Asia-Pacific region. Notwithstanding its regional character, the annual APEC leaders` summits significance is comparable with that of the key global governance institutions, such as the G8 and G20, summits. With increasing integration and enhanced economic relationships as well as established interaction pattern the APEC influence on regional and global economic agenda is growing. In spite of the fact that APEC initially positioned itself as a “free group of economics” not a political association, the member states step-by-step turn to the most acute worldwide political issues, which is reflected in the leaders` statements made during the summit. The analysis of the APEC 2013 summit which was held within the Indonesian presidency on 7-8 October 2013 on Bali provides an insight into the main drivers of the APEC agenda. Given that currently all countries face similar economic and social challenges: low and stalling economic growth, need to pursue fiscal consolidation, persistent structural unemployment, widening income disparities, base erosion and profit shifting as well as tax evasion, climate change negative consequences etc, it`s useful to analyze the measures implemented at the regional level (APEC), as well as the global level (G20). A comparison with the G20 is largely determined shared challenges and by the intersecting memberships: almost half of the members of the institutions participate in both fora, namely Australia, Canada, China, Indonesia, Japan, Mexico, Republic of Korea, Russia and the United States. The recent APEC and G20 agendas aim to coordinate actions to resolve the shared problems and move towards new growth models. The analysis is based on the key summit documents - Bali Declaration “Resilient Asia-Pacific, Engine of Global Growth”, Joint Ministerial Statement, leaders` statements and accompanying documents. The analysis permits to identify the vector of APEC agenda development.
This paper outlines the phenomenon of «fear» as a component of Thomas Hobbes (1588-1679) philosophy. The author makes an attempt to submit the concept of the «rational» fear as the basis of political philosophy of the English philosopher, with a special attention given to some «problematic» place of this concept.
On May 18-19, 2012, at the presidential retreat in Camp David in Maryland, U.S. president Barack Obama hosted the 38th annual G8 summit. The leaders discussed global economic growth, development, and peace and security. After less than 24 hours of face-to-face time among the leaders, they issued communiqué of only five pages. However, Camp David was a significant success. The leaders came together to effectively address the most pressing issues of the day while setting the direction for the summits that were to follow, including the summit of the North Atlantic Treaty Organization in Chicago, the G20 in Los Cabos, Mexico, and the Rio+20 Summit in Rio de Janeiro, Brazil. That success was propelled by several causes. The first is the set of strong global shocks were particularly relevant to a number of items on the agenda. This included the newest installment of the euro-crisis, spikes in oil and food prices, and the escalating violence in Syria. The second is the failure of the other major international institutions to address these challenges. The third is the club’s dedication to the promotion of democracy and its significance on issues such as the democratic transition in the Middle East and North Africa. The fourth is the high relative capabilities of G8 members, fuelled by the strength of the U.S. dollar, the Japanese yen and the British pound. The fifth is the domestic political control, capital, continuity, competence and commitment of the leaders in attendance. Camp David saw several G8 leaders returning for their sixth or seventh summit and leaders with a secure majority mandate and control of their legislative houses at home. Finally, the constricted participation at the remote and secluded Camp David Summit, a unique and original advantage of the G8 summit style, allowed for more spontaneous conversation and interpersonal bonds. Together, these interconnected causes brought the G8 back, as a broader, bigger, bolder centre of effective global governance.
The post-Cold War Arctic has seen a transformation from military tension and a focus on national security to a concern for environmental and human security. As a result of this, the globalized Arctic has a high level of peace and stability, maintained by international cooperation between the Arctic states, northern indigenous peoples, sub-national governments and local actors. There has also been a shift from environmental protection to economic activities and, consequently, states easily trump other interests. Now, in the Arctic, these challenges require fresh thinking on a local and global scale. Regional wars, the 'war on terror', and economic crises have posed new threats to Northern security order.
The article is devoted to the investigation of genesis of regular army as a political institution in conditions of political transit in Libya. The chronological scope of the study covers the historical period from 1951, when a sovereign Libyan state with monarchical form of government appeared, until 2011, when Libyan Jamahiriya ceased to exist. We scrutinize problems of collaboration of army with traditional and modern institutions of Libyan society and state; participation of army in development and implementation of domestic and foreign policy. We also examine how system of checks and balances of participation of army in the political process was established and how it was functioning during in the monarchical (1951-1969), Republican (1969-1976) and Jamahiriya (1976-2011) period. The events of 2011-2014 demonstrate the conservation of discovered trends and patterns of socio-political development of the institution of regular army in the new Libyan state.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traﬃc is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the ﬁnal node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a ﬁnite-dimensional system of diﬀerential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of diﬀerential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
Existing approaches suggest that IT strategy should be a reflection of business strategy. However, actually organisations do not often follow business strategy even if it is formally declared. In these conditions, IT strategy can be viewed not as a plan, but as an organisational shared view on the role of information systems. This approach generally reflects only a top-down perspective of IT strategy. So, it can be supplemented by a strategic behaviour pattern (i.e., more or less standard response to a changes that is formed as result of previous experience) to implement bottom-up approach. Two components that can help to establish effective reaction regarding new initiatives in IT are proposed here: model of IT-related decision making, and efficiency measurement metric to estimate maturity of business processes and appropriate IT. Usage of proposed tools is demonstrated in practical cases.