Vladimir Zakharov

Lomonosov Moscow State University | MSU · Department of Mathematical Cybernetics

Comparative data on the molecular weight distribution of polymers obtained by polymerization of ethylene, propylene and 1‐hexene, and copolymerization of ethylene with α‐olefins over the titanium‐magnesium catalysts (TMC) in the absence and presence of hydrogen are presented. In contrast to the ethylene polymerization, in the cases of propylene and...

Mathematical models of distributed computations, based on the calculus of mobile processes (π-calculus) are widely used for checking the information security properties of cryptographic protocols. Since π-calculus is Turing-complete, this problem is undecidable in general case. Therefore, the study is carried out only for some special classes of π-...

One of the most simple models of computation which is suitable for representation of reactive systems behaviour is a finite state transducer which operates over an input alphabet of control signals and an output alphabet of basic actions. The behaviour of such a reactive system displays itself in the correspondence between flows of control signals...

Finite State Machines (FSMs) are widely used as formal models for solving numerous tasks in software engineering, VLSI design, development of telecommunication systems, etc. To describe the behavior of a real-time system one could supply FSM model with clocks - a continuous time parameters with real values. In a Timed FSM (TFSM) inputs and outputs...

Sequential reactive systems represent programs that interact with the environment by receiving signals or requests and react to these requests by performing operations with data. Such systems simulate various software like computer drivers, real-time systems, control procedures, online protocols etc. In this paper, we study the verification problem...

One of the priority problems in the development and use of databases is that of information security. It becomes substantially more complicated when databases are implemented in cloud computing systems. In our previous paper we studied this problem for the simple case of databases with one-bit records; we offered a criterion of deductive security f...

First-order program schemata represent one of the most simple models of sequential imperative programs intended for solving verification and optimization problems. We consider the decidable relation of logical-thermal equivalence on these schemata and the problem of their size minimization while preserving logical-thermal equivalence. We prove that...

Finite state transducers over semigroups are regarded as a formal model of sequential reactive programs that operate in the interaction with the environment. At receiving a piece of data a program performs a sequence of actions and displays the current result. Such programs usually arise at implementation of computer drivers, on-line algorithms, co...

We study certain simple models of confidential databases in cloud computing systems. In the framework of these models we introduce a concept of deductive security for queries to such databases, find necessary and sufficient conditions of deductive security, and describe some classes of queries which satisfy these requirements.

First-order program schemata is one of the simplest models of sequential imperative programs intended for solving verification and optimization problems. We consider the decidable relation of logical-thermal equivalence of these schemata and the problem of their size minimization while preserving logical-thermal equivalence. We prove that this prob...

Dynamic mechanical analysis was used to study ethylene/1-hexene copolymers with different compositions, molecular weight distributions, and profiles of short-chain branching (SCB) versus molecular weight. These copolymers were produced over a highly active supported titanium–magnesium catalyst (TMC), a highly active supported vanadium–magnesium cat...

We study a formal model of cloud computing systems with auxiliary cryptoservers. Assuming an existence of a secure threshold somewhat homomorphic public key cryptosystem we show how to build a cloud computing system secure in this model.

To verify real-time properties of UML statecharts one may apply a UPPAAL, toolbox for model checking of real-time systems. One of the most suitable ways to specify an operational semantics of UML statecharts is to invoke the formal model of Hierarchical Timed Automata. Since the model language of UPPAAL is based on Networks of Timed Automata one ha...

Designing network update algorithms is an important line of research in developing software for new-generation telecommunication networks—software defined networks (SDNs). A specific case of the network update problem is seamless recovery of network configurations after the loss of some forwarding rules, as can happen, e.g., due to expiry of their...

Checking the correctness of distributed systems is one of the most difficult and urgent problems in software engineering. A combined toolset for the verification of real-time distributed systems (RTDS) is described. RTDSs are specified as statecharts in the Universal Modeling Language (UML). The semantics of statecharts is defined by means of hiera...

Finite state transducers over semigroups can be regarded as a formal model of sequential reactive programs. In this paper we introduce a uniform technique for checking effectively functionality, k-valuedness, equivalence and inclusion for this model of computation in the case when a semigroup these transducers operate over is embeddable in a decida...

Software-defined networking (SDN) is an approach to building computer networks that separate and abstract data planes and control planes of these systems. In a SDN a centralized controller manages a distributed set of switches. A set of open commands for packet forwarding and flow-table updating was defined in the form of a protocol known as OpenFl...

To verify real-time properties of UML statecharts one may apply a UPPAAL, toolbox for model checking of real-time systems. One of the most suitable ways to specify an operational semantics of UML statecharts is to invoke the formal model of Hierarchical Timed Automata. Since the model language of UPPAAL is based on Networks of Timed Automata one ha...

Finite state transducers extend the finite state automata to model functions on strings or lists. They may be used also as simple models of sequential reactive programs. These programs operate in the interaction with the environment permanently receiving data (requests) from it. At receiving a piece of data such program performs a sequence of actio...

Equivalence checking algorithms found vast applications in system programming; they are used in software refactoring, security checking, malware detection, program integration, regression verification, compiler verification and validation. In this paper we show that equivalence checking procedures can be utilized for the development of global optim...

Designing of network update algorithms is urgent for development of SDN control software. A particular case of Network Update Problem is that of adding a set of forwarding rules into flow-tables of SDN switches (say, to install new paths in the network) or restoring seamlessly a given network configuration after some packet forwarding rules have be...

In this paper we present a VERifying MONiTor (VERMONT) which is a software toolset for checking the consistency of network configurations with formally specified invariants of Packet Forwarding Policies (PFP). Correct and safe management of networks is a very hard task. Every time the current load of flow tables should satisfy certain requirements....

Software-dened networking (SDN) is an approach to building computer net-works that separate and abstract data planes and control planes of these systems. In a SDN a centralized controller manages a distributed set of switches. A set of open commands for packet forwarding and ow-table updating was dened in the form of a protocol known as OpenFlow. I...

In this paper we study the equivalence problem in the model of sequential programs which assumes that some instructions are commutative and absorbing. Two instructions are commutative if the result of their executions does not depend on an order of their execution. An instruction b absorbs an instruction a if the sequential composition a;b yields t...

Program obfuscation is a semantic-preserving transformation aimed at bringing a program into a form that impedes understanding of its algorithm and data structures or prevents extracting certain valuable information from the text of the program. Since obfuscation may find wide use in computer security, information hiding and cryptography, security...

The designing of network update algorithms is urgent for the development of SDN control software. A particular case of Network Update Problem is that of restoring seamlessly a given network configuration after some packet forwarding rules have been disabled (say, at the expiry of their time-outs). We study this problem in the framework of a formal...

Software-defined networking (SDN) is an approach to building computer net-works that separate and abstract data planes and control planes of these systems. In a SDN a centralized controller manages a distributed set of switches. A set of open com-mands for packet forwarding and flow-table updating was defined in the form of a pro-tocol known as Ope...

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OpenFlow. На основе аппарата булевых функций и дискретных преобразователей нами предложена формаль-ная модель ПКС, введен прототип формального языка спецификаций, постав-лены задачи верификации моделей ПКС и получены оценки их сложности. Для одной из задач верификации моделей ПКС описан метод ее решения, на основе которого разработано программно-ин...

The data on the effect of polymerization duration on molecular weight (MW), molecular weight distribution (MWD), and content of α‐olefin were obtained for ethylene/1‐hexene copolymers produced on a supported titanium–magnesium catalyst (TMC) upon polymerization in the absence and presence of hydrogen. An increase in MW, narrowing of the MWD, and a...

Strong (logic&term) equivalence of programs is the weakest decidable equivalence relation which approximates the functional equivalence of programs. In this paper we develop a new variant of the algorithm for checking strong equivalence of programs. A distinguished feature of our algorithm is that it relies completely on the algebra of finite subst...

The data on the effects of polymerization duration, cocatalyst, and monomer concentrations upon ethylene polymerization in the absence of hydrogen, and the effect of an additional chain transfer agent (hydrogen) on the molecular weight (MW), molecular weight distribution (MWD), and content of vinyl terminal groups for polyethylene (PE) produced ove...

A uniform verification problem for parameterized systems is to determine whether a temporal property is satisfied for every instance of the system which is composed of an arbitrary number of homogeneous processes. To cope with this problem we combine an induction-based technique for invariant generation and conventional model checking of finite sta...

This paper shows how two-tape automata can be employed to design efficient equivalence checking procedures for sequential programs. The semantics of sequential programs is defined in terms of dynamic logic structures. If a dynamic frame is acyclic (i.e., all program statements are irreversible), then it can be specified by means of a two-tape deter...

The catalyst systems Cr(acac)3/pyrrole/AlEt3/AlEt2Cl and Cr(EH)3/pyrrole/AlEt3/AlEt2Cl in cyclohexane (EH = 2-ethylhexanoate), modeling the Phillips ethylene trimerization catalyst, have been studied by EPR spectroscopy. The effect of various components of these catalyst systems on the concentration of Cr(III) and Cr(I) species and ethylene trimeri...

This paper presents an initiative program aimed at enhancing Linux device driver designing and maintenance by launching a long-term process that will attend the OS kernel development. This process includes two adjacent lines of activity: 1) creation and replenishment of a repository of potential faults and errors that may occur in Linux device driv...

A term t is called a template of terms t 1 and t 2 iff t 1 = tη 1 and t 2 = tη 2, for some substitutions η 1 and η 2. A template t of t 1 and t 2 is called the most specific iff for any template t′ of t 1 and t 2 there exists a substitution ξ such that t = t′ξ. The anti-unification problem is that of computing the most specific template of two give...

The problem of equivalence of interrupt handling programs in two algebraic models is studied. Program operators are divided into two classes, namely, the classes of basic operators and interrupt handling operators. The first model obeys the absorption law, i.e., each basic operator suppresses the result of application of any interrupt handling oper...

We suggest a new algorithm of anti-unification of logic terms represented by acyclic directed graphs and estimate its complexity. The anti-unification problem consists of the following: for two given terms find the most specific term that has the given terms as instances. We suggest an anti-unification algorithm whose complexity linearly depends on...

We present the preliminary results of our work on designing an automatic toolset for verification of Linux kernel-space drivers. By now the toolset includes three components: • a library of verification models; each model is a formal description of some safety property to be checked; • a preprocessor unit; it is intended for simulating an envi-ronm...

Program obfuscation is a semantic-preserving transformation aimed at bringing a program into such a form, which impedes the understanding of its algorithm and data structures or prevents extracting of some valuable information from the text of a program. Since obfuscation could find wide use in computer security, information hiding and cryptography...

We present an encoding of the mobile ambients without communication into a subset of the π-calculus, namely the localized sum-free synchronous π-calculus. We prove the operational correspondence between the two formalisms. A key idea of the encoding is the separation of the spatial structure of mobile ambients from their operational semantics. The...

Polymorphic and metamorphic viruses are the most sophisticated malicious programs that give a lot of trouble to virus scanners. Each time when these viruses infect new executables or replicate themselves, they completely modify (obfuscate) their signature to avoid being detected. This contrivance poses a serious threat to antivirus software that re...

The main goal of model checking is to verify whether a model of a given program satisfies some given specification. In this paper models are regarded as fair or ordinary Kripke structures whereas specifications are represented by formulae branching-time temporal logics (CTL\X or ACTL\X ). Model checking can be substantially enhanced by reducing the...

We study a formal model of imperative sequential programs and focus on the equivalence problem for some class of programs with mode switching whose runs can be divided into two stages. In the first stage a program selects an appropriate mode of computation. Several modes may be tried (switched) in turn before making the ultimate choice. Every time...

Solutions containing mixtures of methylalumoxane (MAO) and iBu3Al give rise to 1H NMR signals indicative of the presence of the mixed alkyl aluminum dimers iBu 2Al(μ-Me)2AriBu2 and of mixed clusters of the type (AlMe(1+2x-y) iBuyO( 1-x))n. These mixed clusters, as well as related species present in solutions containing either MAO-Et3Al or commercia...

Novel data on the composition of active centers of Ziegler-Natta catalysts and on the mechanism of propagation and chain transfer reactions are reviewed. These data are derived from the following trends in the study of the mechanism of catalytic polymerization: a) determination of the number of active centers (mainly with the use of radioactive CO...

Cited By (since 1996): 2, Export Date: 28 May 2011, Source: Scopus

In the paper, a functional parallel programming system implemented on clusters is discussed. It includes a language of compositional functional parallel programming, program development tools, and tools for controlling parallel code execution on the ...

Data on ethylene polymerization over supported LFeCl2/MgCl2 catalysts {L = 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridyl} containing AlR3 (R = Me, Et, i-Bu, or n-Oct) as an activator are presented. These catalysts are highly active (100–300 kg of polyethylene/g of Fe h bar of C2H4) and stable in ethylene polymerization at 70–80 °C. Data on the e...

The supported catalysts for ethylene polymerization were prepared by interaction of 2,6-bis[1-(2,6-dimetilphenylimino)-ethyl]pyridineiron(II) dichloride (LFeCl2) with silica and alumina. The catalysts exhibit high and stable activity at ethylene polymerization in presence of Al(i-Bu)3 as co-catalyst. LFeCl2 interaction with surface functional group...

A new notion of metasubstitution, generalizing the notion of substitution, widely known in the calculation theory, is introduced. The metasubstitutions permits to determine the operations of composition and calculation so as these operations submit to the distributivity laws. In consequence the metasubstitutions are more convenient for their using...

The intermediates of olefin polymerization over homogeneous catalysts based on bis(imino)pyridine iron(II) chloride (LFeCl2, L = 2,6-bis[(1-2,6-dimethylphenylimino)ethyl]pyridine) with different activators (trimethyl-, triisobutyl-, trioctylaluminum and MAO) have been studied by 1H and 2H NMR. In conditions approaching real polymerization, neutral...

By obfuscation we mean any efficient semantic-preserving transformation of computer programs aimed at bringing a program into such a form, which impedes the understanding of its algorithm and data structures or prevents the extracting of some valuable information from the plaintext of a program. Some results obtained recently testify that it is ver...

By obfuscation we mean any efficient semantic-preserving transformation of computer programs aimed at bringing a program into such a form, which impedes the understanding of its algorithm and data structures or prevents the extracting of some valuable information from the plaintext of a program. The main difficulty in designing an effective program...

In this paper we present a straightforward approach to the obfuscation of sequential program control-flow in order to design tamper-resistant software. The principal idea of our technique is as follows: Let I be an instance of a hard combinatorial problem C, whose solution K is known. Then, given a source program π, we implant I into π by applying...

1H and 2H NMR spectroscopic monitoring of ferrous species formed via interaction of 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridineiron(II) chloride (1) with AlMe3, MAO, AlMe3/B(C6F5)3 and AlMe3/CPh3 (C6F5)4 is reported. At interaction of 1 with MAO in toluene solution, the new stable heterodinuclear neutral complexes with proposed structures LFe...

This paper presents a survey of fundamental concepts and main results in studying the equivalence problem for computer programs. We introduce some of the most-used models of computer programs, give a brief overview of the attempts to refine the boarder between decidable and undecidable cases of the equivalence problem for these models, and discuss...

Ethylene polymerization on supported vanadium-magnesium catalysts with the composition VCl4/MgCl2 and VOCl3/MgCl2 was studied in the presence of hydrogen as the chain transfer agent. Vanadium-magnesium catalysts (VMC) are known to exhibit a high reactivity towards hydrogen. This reactivity is manifested as a sharp decrease in polyethylene (PE) mole...

This paper contains a comparative analysis of three toolsets and associated techniques for development of embedded systems. The comparison is based on the experience acquired by applying the techniques to a common case study. The results of the analysis are being used to design a unified set of tools for embedded systems development. Keywords: Form...

Using 1H and 13C NMR spectroscopy, the interaction between Cp2ZrMe2 and MAO in toluene solution was investigated in a wide range of Al/Zr ratios (10–4 000). Several intermediates (I–IV) were detected in the reaction. The structures of these intermediates were elucidated from detailed analysis of 13C-1H NMR data. Intermediate I is a weak complex of...

We present a uniform and easy-to-use technique for deciding the equivalence problem for deterministic monadic linear recursive programs. The key idea is to reduce this problem to the well-known group-theoretic problems by revealing an algebraic nature of program computations. We show that the equivalence problem for monadic linear recursive program...

We introduce a new class OrtSP of first-order sequential programs. This class of programs is characterized by means of orthogonal substitutions θ = x1/t1, ..., xn/tn such that none of the terms ti occurs in the other terms tj, j ≠ i. We show that the equivalence problem for programs in OrtSP is decidable. We select also a subclass OrtSP out of orth...

The molecular structure of polyethylene (PE) produced with supported titanium-magnesium (TMC) and vanadium-magnesium (VMC) catalysts has been studied by means of IR and 13C NMR spectroscopic methods. It has been shown that PE produced with VMC in the presence of hydrogen differs by a lower content of double bonds and higher branching compared with...

The main result of the present paper is the construction of a polynomial algorithm that resolves the c-equivalence of program schemes. This algorithm is constructed on the basis of the analysis of the semantic properties of c-equivalent schemes. The analysis carried out is of interest in and of itself since it suggests a method for the search of ef...

The aim of this paper is to present a unified and easy-to-use technique for deciding the equivalence problem for propositional deterministic programs. The key idea is to reduce this problem to the well-known group-theoretic problems by revealing an algebraic nature of program computations. By applying the main theorems of this paper to some traditi...

Two main approaches are applied for simulation and analysis of the behaviour of distributed computer systems in the Petri net theory. The first approach uses the notion of firing sequences and corresponds to the semantics of alternating parallel calculations. The second one is based on the notion of process-net and corresponds to the semantics of p...

Solving problems of analysis and optimization of computing programs in algorithmic systems is complicated by non-recursiveness of functional properties of programs. According to Rice’s theorem, in a universal programming language any property of programs which depends only on the functions computed by them is algorithmically undecidable. Therefore...

Extended X-ray absorption fine structure analysis (EXAFS) has been used to study supported TiCl4/MgCl2 catalysts containing 1.8 wt.-% Ti. Adsorbed TiCl4 was found to exist on the MgCl2 surface as a dimeric complex. The possible structures of dimeric TiCl4 complexes on the (100) face of MgCl2 are discussed.

The two most frequently used semantics of parallel computations – interleaving semantics and partial order semantics – are considered. When using logical methods for the verification of parallel and distributed programs, the computation set is represented by a model (or a set of models) in one of the nonclassical logics – temporal or causality logi...

This paper offers a satisfiability checking algorithm for the future fragment of Propositional Linear Temporal Logic. The algorithm combines the automata theoretic approach to the verification of temporal formulae and the symbolic computation technique in terms of monotone boolean disjunctive normal forms. The algorithm is given as follows. A tempo...

A description and mathematical justification of the system for translating the operator procedures of programming languages like PASCAL into logical programs suitable for operation in the TURBO-PROLOG system has been suggested. This method for translation is meant for increasing the efficiency of designing logical programs and facilitate verificati...