Improving BDD Based Symbolic Model Checking with Isomorphism Exploiting Transition Relations

Symbolic model checking by using BDDs has greatly improved the applicability of model checking. Nevertheless, BDD based symbolic model checking can still be very memory and time consuming. One main reason is the complex transition relation of systems. Sometimes, it is even not possible to generate the transition relation, due to its exhaustive memory requirements. To diminish this problem, the use of partitioned transition relations has been proposed. However, there are still systems which can not be verified at all. Furthermore, if the granularity of the partitions is too fine, the time required for verification may increase. In this paper we target the symbolic verification of asynchronous concurrent systems. For such systems we present an approach which uses similarities in the transition relation to get further memory reductions and runtime improvements. By applying our approach, even the verification of systems with an previously intractable transition relation becomes feasible.Comment: In Proceedings GandALF 2011, arXiv:1106.081

Automata-theoretic and bounded model checking for linear temporal logic

In this work we study methods for model checking the temporal logic LTL. The focus is on the automata-theoretic approach to model checking and bounded model checking. We begin by examining automata-theoretic methods to model check LTL safety properties. The model checking problem can be reduced to checking whether the language of a finite state automaton on finite words is empty. We describe an efficient algorithm for generating small finite state automata for so called non-pathological safety properties. The presented implementation is the first tool able to decide whether a formula is non-pathological. The experimental results show that treating safety properties can benefit model checking at very little cost. In addition, we find supporting evidence for the view that minimising the automaton representing the property does not always lead to a small product state space. A deterministic property automaton can result in a smaller product state space even though it might have a larger number states. Next we investigate modular analysis. Modular analysis is a state space reduction method for modular Petri nets. The method can be used to construct a reduced state space called the synchronisation graph. We devise an on-the-fly automata-theoretic method for model checking the behaviour of a modular Petri net from the synchronisation graph. The solution is based on reducing the model checking problem to an instance of verification with testers. We analyse the tester verification problem and present an efficient on-the-fly algorithm, the first complete solution to tester verification problem, based on generalised nested depth-first search. We have also studied propositional encodings for bounded model checking LTL. A new simple linear sized encoding is developed and experimentally evaluated. The implementation in the NuSMV2 model checker is competitive with previously presented encodings. We show how to generalise the LTL encoding to a more succint logic: LTL with past operators. The generalised encoding compares favourably with previous encodings for LTL with past operators. Links between bounded model checking and the automata-theoretic approach are also explored.reviewe

Waste People and the Vampiric Society

Chen Qiufan’s 2013 novel Waste Tide has become one of the most popular stories in Chinese New Wave Science Fiction, especially after the publication of its English version in 2019. This essay argues that in addition to the environmental concerns Waste Tide brings to the fore, the novel also calls for a discussion centered on migrant workers in China. Rendered as waste people on Silicon Isle, these migrant workers find themselves trapped in the duality of "economic acceptance" and "social rejection," forming an autonomous community that can be read through Michel Foucault’s notion of heterotopia. Out of the humiliation imposed by the Silicon Isle natives and the resulting mentality of failure and trauma, the waste people have developed a desire for change and transgression. However, their efforts and sacrifice for self-liberation turn out to be in vain, because in doing so, they are consumed by the vampiric logic of market competition. Such a competition, in fact, is evident not only in the fictional Silicon Isle, but also in the real cities benefitting from China’s market-oriented transition

General Purpose Technologies and Productivity Surges: Historical Reflections on the Future of the ICT Revolution

Presented to the International Symposium on ECONOMIC CHALLENGES OF THE 21ST CENTURY IN HISTORICAL PERSPECTIVE, Oxford, England, 2nd-4th July, 1999 Celebrating the Scholarly Career of Charles H. Feinstein, FBA. Re- examination of early twentieth century American productivity growth experience sheds light on the general phenomenon of recurring prolonged swings in total factor productivity (TFP) growth rate experienced in the advanced industrial economies. After a “productivity slowdown” lasting more than a quarter of a century (during which TFP for in the manufacturing sector grew at less than 1 percent per annum, industrial TFP surged to average 6 percent per annum during 1919-29. This contributed substantially to the absolute and relative rise of the US domestic economy’s TFP residual, and in many respects it may be seen as the opening of the high-growth era that persisted into the 1970s. The productivity surge marked the culminating phase in the diffusion of “the dynamo” as a general purpose technology (GPT); that saw a shift in the underlying technological regime brought about by the implementation of critical engineering and organizational advances originating in some two decades earlier. Closer analysis reveals the significant concurrence of the factory electrification movement in this period with important structural changes that were taking place in US labor markets; in addition, there were significant complementarities between managerial and organizational innovations and the new dynamo-based factory technology, on the one hand, and, and the reinforcement of both kinds of innovation by the macroeconomic conditions of the 1920s. This more complicated, historical view of the dynamics of GPT diffusion is supported by comparisons of the US experience of factory electrification with the developments taking place in Japanese industry during the 1920’s, and in the UK manufacturing sector during the 1930’s. Concluding sections of the paper reflect on the analogies and contrasts between the historical case of a socio-economic regime transition involving the electric dynamo and the modern experience of the information and communications technology (ICT) revolution. Our formulation the GPT concept in explicitly historical terms contributes to explaining the paradoxical phenomenon of the late twentieth century productivity slowdown in the US. It also points to some contemporary portents of a future phase of more rapid ICT-based growth in total factor productivity.

Political Shaping Of Transitions To Biofuels In Europe, Brazil And The USA

Faced with major challenges of global climate change, declining fossil fuel reserves, and competition between alternative uses of land, the transition to renewable transport fuels has been marked by new modes of political economic governance and the strategic direction of innovation. In this paper, we compare the different trajectories to the development and uptake of biofuels in Europe, Brazil and the USA. In terms of the timing, direction, and development of biofuels for road transport, the early lead taken by Brazil in sugarcane based ethanol and flex-fuel cars, the USA drive to corn-to-ethanol, and the European domination of biodiesel from rapeseed, manifest significant contrasts at many levels. Adopting a neo-Polanyian ?instituted economic process? approach we argue that the contrasting trajectories exemplify the different modes of politically instituting markets. We analyse the contrasting weight and impact of different drivers in each case (energy security, climate change mitigation, rural economy development, and market opportunity) in the context of diverse initial conditions and resource endowments. We explore the ?politics of markets? that arise from the different modes of instituting markets for ecologically sustainable economic growth, including the role of NGOs, the scientific controversies over land-use change, and the contrasting political institutions in our case studies. We also place our analysis in the historical perspective of other major carbon energy transitions (charcoal to coal, coal to petrochemicals). In so doing, we explore the idea of the emergence of new modes of governance of contemporary capitalist political economies, and the significance of politically directed innovation. The research is based on an extensive primary research programme of in-depth interviews with strategic players in each of the geographic regions, qualitative institutional analysis, a scenario workshop, and secondary data analysis

The “Post” in Postscript: Post-Productive Thinking, Re-Formatted Images

In this article, I seek to discuss the principles of modulation and variation in Deleuze’s canonical essay “Postscript on the Societies of Control” (Deleuze 1992). Analyzing and testing what Deleuze recognizes as “inseparable variations, forming a system of variable geometry” and as a “self-deforming cast that will continuously change from one moment to the other […], like a sieve whose mesh will transmute from point to point” (1992: 4), I will focus on the digital imag

On the creation of a secure key enclave via the use of memory isolation in systems management mode

One of the challenges of modern cloud computer security is how to isolate or contain data and applications in a variety of ways, while still allowing sharing where desirable. Hardware-based attacks such as RowHammer and Spectre have demonstrated the need to safeguard the cryptographic operations and keys from tampering upon which so much current security technology depends. This paper describes research into security mechanisms for protecting sensitive areas of memory from tampering or intrusion using the facilities of Systems Management Mode. The work focuses on the creation of a small, dedicated area of memory in which to perform cryptographic operations, isolated from the rest of the system. The approach has been experimentally validated by a case study involving the creation of a secure webserver whose encryption key is protected using this approach such that even an intruder with full Administrator level access cannot extract the key