33 research outputs found
Beyond oracles – a critical look at real-world blockchains
This thesis intends to provide answers to the following questions: 1) What is the oracle problem, and how do the limitations of oracles affect different real-world applications? 2) What are the characteristics of the portion of the literature that leaves the oracle problem unaddressed? 3) Who are the main contributors to solving the oracle problem, and which issues are they focusing on? 4) How can the oracle problem be overcome in real-world applications? The first chapter aims to answer the first question through a literature review of the most current papers published in the field, bringing clarity to the blockchain oracle problem by discussing its effects in some of the most promising real-world blockchain applications. Thus, the chapter investigates the sectors of Intellectual Property Rights (IPRs), healthcare, supply chains, academic records, resource management, and law. By comparing the different applications, the review reveals that heterogeneous issues arise depending on the sector. The analysis supports the view that the more trusted a system is, the less the oracle problem has an impact. The second chapter presents the results of a systematic review intended to highlight the state-of-the-art of real-world blockchain applications using the oracle problem as a lens of analysis. Academic papers proposing real-world blockchain applications were reviewed to see if the authors considered the oracle’s role in the applications and related issues. The results found that almost 90% of the inspected literature neglected the role of oracles, thereby proposing incomplete or irreproducible projects. Through a bibliometric analysis, the third chapter sheds light on the institutions and authors that are actively contributing to the literature on oracles and promoting progress and cooperation. The study shows that, although there is still a lack of collaboration worldwide, there are dedicated authors and institutions working toward a similar and beneficial cause. The results also make it clear that most areas of oracle research are poorly addressed, with some remaining untouched. The fourth and last chapter focuses on a case study of a dairy company operating in the northeast region of Italy. The company applied blockchain technology to support the traceability of their products worldwide, and the study investigated the benefits of their innovation from the point of view of sustainability. The study also considers the role of oracle management, as it is a critical aspect of a blockchain-based project. Thus, the relationship between the company, the blockchain oracle, and the supervising authority is discussed, offering insight into how sustainable innovations can positively impact supply chain management. This work as a whole aims to shed light on blockchain oracles as an academic area of research, explaining why the study of oracles should be considered the backbone of blockchain literature development
Numerical assessment of the percolation threshold using complement networks
Models of percolation processes on networks currently assume locally
tree-like structures at low densities, and are derived exactly only in the
thermodynamic limit. Finite size effects and the presence of short loops in
real systems however cause a deviation between the empirical percolation
threshold and its model-predicted value . Here we show the
existence of an empirical linear relation between and across a
large number of real and model networks. Such a putatively universal relation
can then be used to correct the estimated value of . We further show how
to obtain a more precise relation using the concept of the complement graph, by
investigating on the connection between the percolation threshold of a network,
, and that of its complement,
From Reality Keys to Oraclize. A Deep Dive into the History of Bitcoin Oracles
Before the advent of alternative blockchains such as Ethereum, the future of
decentralization was all in the hands of Bitcoin. Together with Nakamoto
itself, early developers were trying to leverage Bitcoin potential to
decentralize traditionally centralized applications. However, being Bitcoin a
decentralized machine, available non-trustless oracles were considered
unsuitable. Therefore, strategies had to be elaborated to solve the so-called
oracle problem in the newborn scenario. By interviewing early developers and
crawling early forums and repositories, this paper aims to retrace and
reconstruct the chain of events and contributions that gave birth to oracles on
Bitcoin. The evolution of early trust models and approaches to solving the
oracle problem is also outlined. Analyzing technical and social barriers to
building oracles on Bitcoin, the transition to Ethereum will also be discussed.Comment: Literature background and methodology are deliberately omitted at
this stage (preprint). To improve readability for a broader audience, the
content is presented more like a stor
Fragility and anomalous susceptibility of weakly interacting networks
Percolation is a fundamental concept that brought new understanding on the
robustness properties of complex systems. Here we consider percolation on
weakly interacting networks, that is, network layers coupled together by much
less interlinks than the connections within each layer. For these kinds of
structures, both continuous and abrupt phase transition are observed in the
size of the giant component. The continuous (second-order) transition
corresponds to the formation of a giant cluster inside one layer, and has a
well defined percolation threshold. The abrupt transition instead corresponds
to the merger of coexisting giant clusters among different layers, and is
characterised by a remarkable uncertainty in the percolation threshold, which
in turns causes an anomalous trend in the observed susceptibility. We develop a
simple mathematical model able to describe this phenomenon and to estimate the
critical threshold for which the abrupt transition is more likely to occur.
Remarkably, finite-size scaling analysis in the abrupt region supports the
hypothesis of a genuine first-order phase transition
Multiple structural transitions in interacting networks
Many real-world systems can be modeled as interconnected multilayer networks,
namely a set of networks interacting with each other. Here we present a
perturbative approach to study the properties of a general class of
interconnected networks as inter-network interactions are established. We
reveal multiple structural transitions for the algebraic connectivity of such
systems, between regimes in which each network layer keeps its independent
identity or drives diffusive processes over the whole system, thus generalizing
previous results reporting a single transition point. Furthermore we show that,
at first order in perturbation theory, the growth of the algebraic connectivity
of each layer depends only on the degree configuration of the interaction
network (projected on the respective Fiedler vector), and not on the actual
interaction topology. Our findings can have important implications in the
design of robust interconnected networked system, particularly in the presence
of network layers whose integrity is more crucial for the functioning of the
entire system. We finally show results of perturbation theory applied to the
adjacency matrix of the interconnected network, which can be useful to
characterize percolation processes on such systems
Structural changes in the interbank market across the financial crisis from multiple core-periphery analysis
Interbank markets are often characterised in terms of a core-periphery
network structure, with a highly interconnected core of banks holding the
market together, and a periphery of banks connected mostly to the core but not
internally. This paradigm has recently been challenged for short time scales,
where interbank markets seem better characterised by a bipartite structure with
more core-periphery connections than inside the core. Using a novel
core-periphery detection method on the eMID interbank market, we enrich this
picture by showing that the network is actually characterised by multiple
core-periphery pairs. Moreover, a transition from core-periphery to bipartite
structures occurs by shortening the temporal scale of data aggregation. We
further show how the global financial crisis transformed the market, in terms
of composition, multiplicity and internal organisation of core-periphery pairs.
By unveiling such a fine-grained organisation and transformation of the
interbank market, our method can find important applications in the
understanding of how distress can propagate over financial networks.Comment: 17 pages, 9 figures, 1 tabl
Overcoming the Blockchain Oracle Problem in the Traceability of Non-Fungible Products
Blockchain implications within the sustainability domain are rapidly arousing the interest of researchers and institutions. However, despite the avalanche of articles, papers, and recently published books, innovation in the blockchain domain is still heavily influenced by light literature, such as news, articles, opinion posts, and white papers. Lacking a homogeneous literature background, case studies often fall into storytelling, providing mere descriptions of the facts according to the writers\u2019 impressions and opinions. We therefore investigate blockchain adoption for sustainable purposes through a case study while remaining firmly grounded in three main theoretical literature streams: knowledge management, knowledge infrastructure, and trust. Since blockchain interaction with the real world is managed by oracles, addressing the oracle problem is essential in order to evaluate the effectiveness of blockchain for sustainability issues. However, to the best of the authors\u2019 knowledge, no other paper has effciently addressed this subject or even mentioned it. Recognizing its scarce consideration in the literature, the oracle problem will be analyzed in both theoretical and practical terms, thereby providing a way to solve the issues related to non-fungible products in the supply chain. Choice over the selected case study was made in light of the divergence in motives for the adoption of blockchain (economic over social), which makes the results more inferable at a broader scale and offers an insight into how sustainable innovations can also be economically viabl
Dimensional reduction of solvency contagion dynamics on financial networks
Study of the application of dimensional reduction methods to the propagation of credit shocks within an interbank network, modeled according to the DebtRank dynamics
True scale-free networks hidden by finite size effects
We analyze about two hundred naturally occurring networks with distinct
dynamical origins to formally test whether the commonly assumed hypothesis of
an underlying scale-free structure is generally viable. This has recently been
questioned on the basis of statistical testing of the validity of power law
distributions of network degrees by contrasting real data. Specifically, we
analyze by finite-size scaling analysis the datasets of real networks to check
whether purported departures from the power law behavior are due to the
finiteness of the sample size. In this case, power laws would be recovered in
the case of progressively larger cutoffs induced by the size of the sample. We
find that a large number of the networks studied follow a finite size scaling
hypothesis without any self-tuning. This is the case of biological protein
interaction networks, technological computer and hyperlink networks, and
informational networks in general. Marked deviations appear in other cases,
especially infrastructure and transportation but also social networks. We
conclude that underlying scale invariance properties of many naturally
occurring networks are extant features often clouded by finite-size effects due
to the nature of the sample data