An ideal multi-secret sharing scheme based on minimal privileged coalitions

How to construct an ideal multi-secret sharing scheme for general access structures is difficult. In this paper, we solve an open problem proposed by Spiez et al.recently [Finite Fields and Their Application, 2011(17) 329-342], namely to design an algorithm of privileged coalitions of any length if such coalitions exist. Furthermore, in terms of privileged coalitions, we show that most of the existing multi-secret sharing schemes based on Shamir threshold secret sharing are not perfect by analyzing Yang et al.'s scheme and Pang et al.'s scheme. Finally, based on the algorithm mentioned above, we devise an ideal multi-secret sharing scheme for families of access structures, which possesses more vivid authorized sets than that of the threshold scheme.Comment: 13page

Antisymmetric multi-partite quantum states and their applications

Entanglement is a powerful resource for processing quantum information. In this context pure, maximally entangled states have received considerable attention. In the case of bipartite qubit-systems the four orthonormal Bell-states are of this type. One of these Bell states, the singlet Bell-state, has the additional property of being antisymmetric with respect to particle exchange. In this contribution we discuss possible generalizations of this antisymmetric Bell-state to cases with more than two particles and with single-particle Hilbert spaces involving more than two dimensions. We review basic properties of these totally antisymmetric states. Among possible applications of this class of states we analyze a new quantum key sharing protocol and methods for comparing quantum states

Institutional Arrangements to Determine Loan Repayment in Chile

The major objective of this paper is to investigate institutional arrangements as a determinant of loan repayment in the Chilean financial market. A second aim is to analyze the effects of these arrangements on borrowers’ behavior. Although La Porta et al. (1997, 1998) classify Chile as a French Civil Law country, the law and private arrangements have evolved consistently with the capital market development to protect the rights of the creditors. This is consistent with relatively low rates of bad loans, ranking from 1. 1 to 2. 0 percent in 1993-1997. We examine different variables which may be related to loan repayment: (a) limitations on the access to credit, (b) macroeconomic stability, (c) collection technology, (d) bankruptcy code, (e) information sharing, (f) the judicial system, (g) prescreening techniques and (h) major changes in financial market regulation. Based on the discussion presented in the paper plus regression analyses, we conclude that a satisfactory performance of the Chilean credit market, in terms of loan repayments and credit market development, hinges on a good information sharing system, an advanced collection technology, a good macroeconomic performance, credit market development and major changes in financial market regulation.

Absolute Maximal Entanglement and Quantum Secret Sharing

We study the existence of absolutely maximally entangled (AME) states in quantum mechanics and its applications to quantum information. AME states are characterized by being maximally entangled for all bipartitions of the system and exhibit genuine multipartite entanglement. With such states, we present a novel parallel teleportation protocol which teleports multiple quantum states between groups of senders and receivers. The notable features of this protocol are that (i) the partition into senders and receivers can be chosen after the state has been distributed, and (ii) one group has to perform joint quantum operations while the parties of the other group only have to act locally on their system. We also prove the equivalence between pure state quantum secret sharing schemes and AME states with an even number of parties. This equivalence implies the existence of AME states for an arbitrary number of parties based on known results about the existence of quantum secret sharing schemes.Comment: 5 pages, 2 figure

Intervention Policy of the BoJ: A Unified Approach

Intervening in the FX market implies a complex decision process for central banks. Monetary authorities have to decide whether to intervene or not, and if so, when and how. Since the successive steps of this procedure are likely to be highly interdependent, we adopt a nested logit approach to capture their relationships and to characterize the prominent features of the various steps of the intervention decision. Our findings shed some light on the determinants of central bank interventions, on the so-called secrecy puzzle and on the identification of the variables influencing the detection of foreign exchange transactions by market traders.FX intervention, secrecy puzzle, market detection, nested logit

The Economics of Knowledge Regulation: An Empirical Analysis of Knowledge Flows

Successful innovation depends on the management of a firm’s knowledge base. This paper empirically investigates the determinants of knowledge regulation. Using a unique survey dataset, the analysis suggests that R&D managers do not leak knowledge randomly, but rather regulate knowledge consciously. We find that the source and the channel of knowledge inflows impact knowledge regulation. The findings reveal that the more a firm profits from knowledge inflows from competitors, the fewer actions it takes to regulate outgoing knowledge. We do not find that the extent of knowledge inflows from collaborating firms impacts knowledge regulation. However, the type of channel being used to acquire knowledge matters. Compared to public channels, the different types of private channels used to access knowledge inflow and the type of the competitive relationship influence the firms’ decision to regulate knowledge outflow in the following way: concerning relationships with competitors, firms regulate knowledge outflow more when using formal channels, but less when using informal channels (although a significant difference is not found with the latter); concerning collaborative relationships, firms regulate knowledge outflow less regardless of whether they are using formal or informal private channels compared to using public channels. Presumably firms that acquire knowledge from competing firms through formal private channels compared to public channels, try to establish opaque and soundproof fences to surround them, whereas firms that acquire knowledge from collaborating firms through formal or informal private channels do not want to restrict circulation, but rather facilitate inter-firm knowledge exchange. Our results have important implications for academics and R&D managers alike

Beyond Gisin's Theorem and its Applications: Violation of Local Realism by Two-Party Einstein-Podolsky-Rosen Steering

We demonstrate here that for a given mixed multi-qubit state if there are at least two observers for whom mutual Einstein-Podolsky-Rosen steering is possible, i.e. each observer is able to steer the other qubits into two different pure states by spontaneous collapses due to von Neumann type measurements on his/her qubit, then nonexistence of local realistic models is fully equivalent to quantum entanglement (this is not so without this condition). This result leads to an enhanced version of Gisin's theorem (originally: all pure entangled states violate local realism). Local realism is violated by all mixed states with the above steering property. The new class of states allows one e.g. to perform three party secret sharing with just pairs of entangled qubits, instead of three qubit entanglements (which are currently available with low fidelity). This significantly increases the feasibility of having high performance versions of such protocols. Finally, we discuss some possible applications.Comment: 9 pages, 1 figur

When Do People Trust Their Social Groups?

Trust facilitates cooperation and supports positive outcomes in social groups, including member satisfaction, information sharing, and task performance. Extensive prior research has examined individuals' general propensity to trust, as well as the factors that contribute to their trust in specific groups. Here, we build on past work to present a comprehensive framework for predicting trust in groups. By surveying 6,383 Facebook Groups users about their trust attitudes and examining aggregated behavioral and demographic data for these individuals, we show that (1) an individual's propensity to trust is associated with how they trust their groups, (2) smaller, closed, older, more exclusive, or more homogeneous groups are trusted more, and (3) a group's overall friendship-network structure and an individual's position within that structure can also predict trust. Last, we demonstrate how group trust predicts outcomes at both individual and group level such as the formation of new friendship ties.Comment: CHI 201