Transaction Propagation on Permissionless Blockchains: Incentive and Routing Mechanisms

Existing permissionless blockchain solutions rely on peer-to-peer propagation mechanisms, where nodes in a network transfer transaction they received to their neighbors. Unfortunately, there is no explicit incentive for such transaction propagation. Therefore, existing propagation mechanisms will not be sustainable in a fully decentralized blockchain with rational nodes. In this work, we formally define the problem of incentivizing nodes for transaction propagation. We propose an incentive mechanism where each node involved in the propagation of a transaction receives a share of the transaction fee. We also show that our proposal is Sybil-proof. Furthermore, we combine the incentive mechanism with smart routing to reduce the communication and storage costs at the same time. The proposed routing mechanism reduces the redundant transaction propagation from the size of the network to a factor of average shortest path length. The routing mechanism is built upon a specific type of consensus protocol where the round leader who creates the transaction block is known in advance. Note that our routing mechanism is a generic one and can be adopted independently from the incentive mechanism.Comment: 2018 Crypto Valley Conference on Blockchain Technolog

Symbolic Model Checking of Concurrent Programs Using Partial Orders and On-the-Fly Transactions

Abstract. The state explosion problem is one of the core bottlenecks in the model checking of concurrent software. We show how to ameliorate the problem by combining the ability of partial order techniques to reduce the state space of the concurrent program with the power of symbolic model checking to explore large state spaces. Our new verification methodology involves translating the given concurrent program into a circuit-based model which gives us the flexibility to then employ any model checking technique of choice – either SAT or BDD-based – for verifying a broad range of linear time properties, not just safety. The reduction in the explored state-space is obtained by statically augmenting the symbolic encoding of the program by additional constraints. These constraints restrict the scheduler to choose from a minimal conditional stubborn set of transitions at each state. Another key contribution of the paper, is a new method for detecting transactions on-the-fly which takes into account patterns of lock acquisition and yields better reductions than existing methods which rely on a lockset based analysis. Moreover unlike existing techniques, identifying on-the-fly transactions does not require the program to follow a lock discipline in accessing shared variables. We have applied our techniques to the Daisy test bench and shown the existence of several bugs.

Computer Aided Verification

This open access two-volume set LNCS 10980 and 10981 constitutes the refereed proceedings of the 30th International Conference on Computer Aided Verification, CAV 2018, held in Oxford, UK, in July 2018. The 52 full and 13 tool papers presented together with 3 invited papers and 2 tutorials were carefully reviewed and selected from 215 submissions. The papers cover a wide range of topics and techniques, from algorithmic and logical foundations of verification to practical applications in distributed, networked, cyber-physical, and autonomous systems. They are organized in topical sections on model checking, program analysis using polyhedra, synthesis, learning, runtime verification, hybrid and timed systems, tools, probabilistic systems, static analysis, theory and security, SAT, SMT and decisions procedures, concurrency, and CPS, hardware, industrial applications

Computer Aided Verification

This open access two-volume set LNCS 10980 and 10981 constitutes the refereed proceedings of the 30th International Conference on Computer Aided Verification, CAV 2018, held in Oxford, UK, in July 2018. The 52 full and 13 tool papers presented together with 3 invited papers and 2 tutorials were carefully reviewed and selected from 215 submissions. The papers cover a wide range of topics and techniques, from algorithmic and logical foundations of verification to practical applications in distributed, networked, cyber-physical, and autonomous systems. They are organized in topical sections on model checking, program analysis using polyhedra, synthesis, learning, runtime verification, hybrid and timed systems, tools, probabilistic systems, static analysis, theory and security, SAT, SMT and decisions procedures, concurrency, and CPS, hardware, industrial applications

Incentives and Human Resource Management in the Design of Public Sector Reform

We, in Pakistan, should be very happy that the global development community has finally accepted the centrality of public sector reform (also known as improved governance) in the quest for improved living standards in poor countries. Development economics is a subject that is based on the interpretation and observation of some Western academics and Western donor-based agencies. We should have some sympathy for these leaders of development thought and policy for they have struggled with integrating the prevailing theme (fad) in Western thought and philanthropy with learning about the societies and economies that they were supposed to be prescribing for. Using the principle of “ends justifying the means”, they defend their reliance on the current “fad” as well as on the only clearly visible, organised and powerful actor—the government, no matter how inefficient—they would. The result is that this approach led to a long era of government-led development, which centralised policy- and decision-making, initiated planning, and created a wide range of public-sector institutions. The role of the government was thus extended into areas that were conceptually indefensible. In this manner, the public servant grew into her new much more lustrous and looser robes. A bloated, over-centralised, and a private sector inhibiting government was created to be the observation and implementation outpost of the development word. This was the first step in the transformation of the public sector in the direction of misgovernance.

The Design of Free-Market Economies in a Post-Neoclassical World

The ‘Washington Consensus’ supporting competitive frames and market solutions in economics and law was shown inadequate to address social problems in non-U.S. settings. So would diversity and dynamics suggest theories in need of adjustment to other realities such as culture, increasing returns and market power. Reform must account for an economics of falling cost, ecological limits and complementarity in our relations. Such shall open new applications for economics and law. In this paper a theory of planning horizons is introduced and then employed to raise some meaningful questions about the neoclassical view with respect to its substitution, decreasing returns and independence assumptions. Suppositions of complementarity, increasing returns and interdependence suggest that competition is inefficient by upholding a myopic culture resistant to change. Growth – though long believed to rise from markets and competitive values – may not derive from these sources. Instead, as civilizations advance, shifting from material wants to higher-order intangible output, they evolve from market tradeoffs (substitution and scarcity) into realms of common need (complementarity and abundance). If so, then neoclassical arguments shall no longer apply to any advanced information economy also restrained by its ecology. Indeed, this paper opens standard theory into a more general framework constructing ‘horizon effects’ into a case for cooperation – as more efficient than competition for all long-term problems of growth. The case is made that competition is keeping us stupid and immature, rewarding a myopic culture at the expense of learning and trust, therefore retarding economic growth instead of encouraging it as believed. The policy implications of horizonal theory are explored, with respect to regulatory aims and economic concerns. Such an approach emphasizes strict constraints against entry barriers, ecological harm, market power abuse and ethical lapses. Social cohesion – not competition – is sought as a means to extend horizons and thereby increase efficiency, equity and ecological health. The overriding importance of horizon effects for regulatory assessment dominates other orthodox standards in economics and law. In sum, much of the reason for the failure of the Washington Consensus stems from myopic concerns central to any horizonal view. Reframing economics along horizonal lines suggests some meaningful insight to how regulations should be designed to keep pace with this approach in economics and law

Using Partial Orders for the Efficient Verification of Deadlock Freedom and Safety Properties

This article presents an algorithm for detecting deadlocks in concurrent finite-state systems without incurring most of the state explosion due to the modeling of concurrency by interleaving. For systems that have a high level of concurrency, our algorithm can be much more efficient than the classical exploration of the whole state space. Finally, we show that our algorithm can also be used for verifying arbitrary safety properties