789 research outputs found
Variability Abstraction and Refinement for Game-Based Lifted Model Checking of Full CTL
One of the most promising approaches to fighting the configuration space explosion problem in lifted model checking are variability abstractions. In this work, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. The practicality of this approach is demonstrated on several variability models
The pricing of infrastructure initial public offerings : evidence from Australia
This paper explores first-day returns on infrastructure entity initial public offerings (IPOs) in Australia from 1996 to 2007. While a good deal has been written on the first-day returns of industrial and mining company IPOs and Real Estate Investment Trust IPOs, first-day returns of infrastructure entity IPOs have yet to be reported in the literature. The study uses ordinary least squares regression analysis to identify factors that might influence the percentage first-day returns theoretically available to investing subscribers and factors that might influence the aggregate amount of money left to subscribers by issuers. The study finds that first-day returns, on average, are not significantly different from zero. There is evidence, however, that suggests higher dividend yields and higher percentage direct costs of capital raising influence these first-day returns. The study also finds that infrastructure entity IPOs that seek to raise more equity capital leave less money on the table for subscribing investors.<br /
Slot Games for Detecting Timing Leaks of Programs
In this paper we describe a method for verifying secure information flow of
programs, where apart from direct and indirect flows a secret information can
be leaked through covert timing channels. That is, no two computations of a
program that differ only on high-security inputs can be distinguished by
low-security outputs and timing differences. We attack this problem by using
slot-game semantics for a quantitative analysis of programs. We show how
slot-games model can be used for performing a precise security analysis of
programs, that takes into account both extensional and intensional properties
of programs. The practicality of this approach for automated verification is
also shown.Comment: In Proceedings GandALF 2013, arXiv:1307.416
A characterization of submanifolds by a homogeneity condition
A very short proof of the following smooth homogeneity theorem of D. Repovs,
E. V. Scepin and the author is presented.
Let N be a locally compact subset of a smooth manifold M. Assume that for
each two points x,y in N there exist their neighborhoods Ux and Uy in M and a
diffeomorphism h : Ux \to Uy such that h(x)=y and h (Ux \cap N) = Uy \cap N.
Then N is a smooth submanifold of M.Comment: 4 pages, meaning-distorting typos correcte
Generalized abstraction-refinement for game-based CTL lifted model checking
cation areas ranging from embedded system domains to system-level software and communication protocols. Software Product Line methods and architectures allow effective building many custom variants of a software system in these domains. In many of the applications, their rigorous verification and quality assurance are of paramount importance. Lifted model checking for system families is capable of verifying all their variants simultaneously in a single run by exploiting the similarities between the variants. The computational cost of lifted model checking still greatly depends on the number of variants (the size of configuration space), which is often huge. Variability abstractions have successfully addressed this configuration space explosion problem, giving rise to smaller abstract variability models with fewer abstract configurations. Abstract variability models are given as modal transition systems, which contain may (over-approximating) and must (under-approximating) transitions. Thus, they preserve both universal and existential CTL properties. In this work, we bring two main contributions. First, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. Second, we propose a new generalized definition of abstract variability models, given as so-called generalized modal transition systems, by introducing the notion of (must) hyper-transitions. This results in more precise abstract models in which more CTL formulae can be proved or disproved. We integrate the newly defined generalized abstract variability models in the existing abstraction-refinement framework for game-based lifted model checking of CTL. Finally, we evaluate the practicality of this approach on several system families
Nonlocal Operational Calculi for Dunkl Operators
The one-dimensional Dunkl operator with a non-negative parameter ,
is considered under an arbitrary nonlocal boundary value condition. The right
inverse operator of , satisfying this condition is studied. An operational
calculus of Mikusinski type is developed. In the frames of this operational
calculi an extension of the Heaviside algorithm for solution of nonlocal Cauchy
boundary value problems for Dunkl functional-differential equations
with a given polynomial is proposed. The solution of these equations in
mean-periodic functions reduces to such problems. Necessary and sufficient
condition for existence of unique solution in mean-periodic functions is found
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