34,370 research outputs found

    Algorithms for Replica Placement in High-Availability Storage

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    A new model of causal failure is presented and used to solve a novel replica placement problem in data centers. The model describes dependencies among system components as a directed graph. A replica placement is defined as a subset of vertices in such a graph. A criterion for optimizing replica placements is formalized and explained. In this work, the optimization goal is to avoid choosing placements in which a single failure event is likely to wipe out multiple replicas. Using this criterion, a fast algorithm is given for the scenario in which the dependency model is a tree. The main contribution of the paper is an O(n+ρlogρ)O(n + \rho \log \rho) dynamic programming algorithm for placing ρ\rho replicas on a tree with nn vertices. This algorithm exhibits the interesting property that only two subproblems need to be recursively considered at each stage. An O(n2ρ)O(n^2 \rho) greedy algorithm is also briefly reported.Comment: 22 pages, 7 figures, 4 algorithm listing

    Pricing and hedging american options analytically: A perturbation method

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    This paper studies the critical stock price of American options with continuous dividend yield. We solve the integral equation and derive a new analytical formula in a series form for the critical stock price. American options can be priced and hedged analytically with the help of our critical-stock-price formula. Numerical tests show that our formula gives very accurate prices. With the error well controlled, our formula is now ready for traders to use in pricing and hedging the S&P 100 index options and for the Chicago Board Options Exchange to use in computing the VXO volatility index. © 2010 Wiley Periodicals, Inc.postprin

    The CBOE S&P 500 Three-month variance futures

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    In this article, we study the market of the Chicago Board Options Exchange S&P 500 three-month variance futures that were listed on May 18, 2004. By using a simple mean-reverting stochastic volatility model for the S&P 500 index, we present a linear relation between the price of fixed time-to-maturity variance futures and the VIX2. The model prediction is supported by empirical tests. We find that a model with a fixed mean-reverting speed of 1.2929 and a daily-calibrated floating long-term mean level has a good fit to the market data between May 18, 2004, and August 17, 2007. The market price of volatility risk estimated from the 30-day realized variance and VIX2 has a mean value of -19.1184. © 2009 Wiley Periodicals, Inc.postprin

    Market excess returns, variance and the third cumulant

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    In this paper, we develop an equilibrium asset pricing model for the market excess return, variance and the third cumulant by using a jump-diffusion process with stochastic variance and jump intensity in Cox, Ingersoll and Ross' (1985) production economy. Empirical evidence with S&P 500 index and options from January 1996 to December 2005 strongly supports our model prediction that lower the third cumulant, higher the market excess returns. Consistent with existing literature, the theoretical mean-variance relation is supported only by regressions on risk-neutral variance. We further demonstrate empirically that the third cumulant explains significantly the variance risk premium.published_or_final_versio

    Bounds and Inequalities Relating h-Index, g-Index, e-Index and Generalized Impact Factor

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    Finding relationships among different indices such as h-index, g-index, e-index, and generalized impact factor is a challenging task. In this paper, we describe some bounds and inequalities relating h-index, g-index, e-index, and generalized impact factor. We derive the bounds and inequalities relating these indexing parameters from their basic definitions and without assuming any continuous model to be followed by any of them.Comment: 17 pages, 6 figures, 5 table

    Is warrant really a derivative? Evidence from the Chinese warrant market

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    This paper studies the Chinese warrant market that has been developing since August 2005. Empirical evidence shows that the market prices of warrants are much higher systematically than the Black-Scholes prices with historical volatility. The prices of a warrant and its underlying asset do not support the monotonicity, perfect correlation and option redundancy properties. The cumulated delta-hedged gains for almost all expired warrants are negative. The negative gains are mainly driven by the volatility risk, and the trading values of the warrants for puts and the market risk for calls. The investors are trading some other risks in addition to the underlying risks. © 2012 Elsevier B.V. All rights reserved.postprin

    Von Neumann Regular Cellular Automata

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    For any group GG and any set AA, a cellular automaton (CA) is a transformation of the configuration space AGA^G defined via a finite memory set and a local function. Let CA(G;A)\text{CA}(G;A) be the monoid of all CA over AGA^G. In this paper, we investigate a generalisation of the inverse of a CA from the semigroup-theoretic perspective. An element τCA(G;A)\tau \in \text{CA}(G;A) is von Neumann regular (or simply regular) if there exists σCA(G;A)\sigma \in \text{CA}(G;A) such that τστ=τ\tau \circ \sigma \circ \tau = \tau and στσ=σ\sigma \circ \tau \circ \sigma = \sigma, where \circ is the composition of functions. Such an element σ\sigma is called a generalised inverse of τ\tau. The monoid CA(G;A)\text{CA}(G;A) itself is regular if all its elements are regular. We establish that CA(G;A)\text{CA}(G;A) is regular if and only if G=1\vert G \vert = 1 or A=1\vert A \vert = 1, and we characterise all regular elements in CA(G;A)\text{CA}(G;A) when GG and AA are both finite. Furthermore, we study regular linear CA when A=VA= V is a vector space over a field F\mathbb{F}; in particular, we show that every regular linear CA is invertible when GG is torsion-free elementary amenable (e.g. when G=Zd, dNG=\mathbb{Z}^d, \ d \in \mathbb{N}) and V=FV=\mathbb{F}, and that every linear CA is regular when VV is finite-dimensional and GG is locally finite with Char(F)o(g)\text{Char}(\mathbb{F}) \nmid o(g) for all gGg \in G.Comment: 10 pages. Theorem 5 corrected from previous versions, in A. Dennunzio, E. Formenti, L. Manzoni, A.E. Porreca (Eds.): Cellular Automata and Discrete Complex Systems, AUTOMATA 2017, LNCS 10248, pp. 44-55, Springer, 201
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