Among functionally complete sets of Boolean functions, sole sufficient operators are of particular interest. They have a wide range of applicability and are not limited to the two-seat case. In this paper, the conditions, imposed on the Zhegalkin polynomial coefficients, are formulated. The conditions are necessary and sufficient for the polynomial to correspond to a sole sufficient operator. The polynomial representation of constant-preserving Boolean functions is considered. It is shown that the properties of monotone and linearity do not require special consideration in describing a sole sufficient operator. The concept of a dual remainder polynomial is introduced. The value of it allows one to determine the self-duality of a Boolean function. It is proved that the preserving 0 and 1 or preserving neither 0 nor 1 Boolean function is self-dual if and only if the dual remainder of its corresponding Zhegalkin polynomial is equal to 0 for any sets of function variable values. Based on this fact, a system of leading coefficients is obtained. The solution of the system made it possible to formulate the criterion for the self-duality of the Boolean function represented by the Zhegalkin polynomial. It imposes necessary and sufficient conditions on the polynomial coefficients. Thus, it is shown that Zhegalkin polynomials are a rather convenient tool for studying precomplete classes of Boolean functions.

The paper proposes an algorithm for solving the problem of finding the maximum common subgraph. Both the sequential and the parallel version of the algorithm, their software implementation are described, and an experimental study of their effectiveness is carried out.

This problem is one of the most famous NP-complete problems. Its solution may be required when solving many practical problems related to the study of complex structures. We solve it in a statement when we need to find all possible isomorphisms of the found common subgraph. Due to the extremely high complexity of the problem, it is natural to want to speed up its solution by parallelizing the algorithm.
To organize parallel computing, the author used the RPM_ParLib library. It allows to develop effective applications for parallel computing on a local network under the control of the runtime environment .NET Framework.The library supports a recursive-parallel programming style and provides effective work distribution and dynamic load balancing of computational modules during program execution. It can be used for applications written in any programming language supported by the .NET Framework.
The purpose of the numerical experiment was to study the acceleration achieved due to the recursive-parallel organization of calculations. For the experiment, the author developed a special application in the C# language designed to generate various sets of initial data with specified parameters. The paper describes the features of the generated initial pairs of graphs, as well as the results obtained during the experiment.

Mixed Boolean-Arithmetic expressions (MBA-expressions) with $t$ integer $n$-bit variables are often used for program obfuscations. Obfuscation consists of replacing short expressions with longer equivalent expressions that seem to take the analyst more time to explore. The paper shows that to simplify linear MBA-expressions (reduce the number of terms), a technique similar to the technique of decoding linear codes by information sets can be applied. Based on this technique, algorithms for simplifying linear MBA-expressions are constructed: an algorithm for finding an expression of minimum length and an algorithm for reducing the length of an expression. Based on the length reduction algorithm, an algorithm is constructed that allows to estimate the resistance of an MBA-expression to simplification. We experimentally estimate the dependence of the average number of terms in a linear MBA-expression returned by simplification algorithms on $n$, the number of decoding iterations, and the power of the set of Boolean functions, by which a linear combination with a minimum number of nonzero coefficients is sought. The results of the experiments for all considered $t$ and $n$ show that if before obfuscation the linear MBA-expression contained $r=1,2,3$ terms, then the developed simplification algorithms with a probability close to one allow using the obfuscated version of this expression find an equivalent one with no more than $r$ terms. This is the main difference between the information set decoding technique and the well-known techniques for simplifying linear MBA-expressions, where the goal is to reduce the number of terms to no more than $2^t$. We also found that for randomly generated linear MBA-expressions with increasing $n$, the average number of terms in the returned expression tends to $2^t$ and does not differ from the average number of terms in the linear expression returned by known simplification algorithms. The results obtained, in particular, make it possible to determine $t$ and $n$ for which the number of terms in the simplified linear MBA-expression on average will not be less than the given one.

A system of three ring-connected generators with asymmetric nonlinearity and special nonlinear coupling is considered. The investigated system simulates an electrical circuit of three identical generators. Each generator is an oscillatory circuit with a nonlinear element. The volt-ampere characteristic of this element has a $S$-shaped character. The nonlinear coupling between the generators is organized in such way that it has a transmission coefficient close to one in the forward direction and close to zero in the reverse direction. First, the problem of finding solutions branching from equilibrium states is studied by asymptotic methods. And then the initial system is investigated by numerical methods. The dependence of the system dynamics on the degree of asymmetry of cubic nonlinearity describing the characteristic of a nonlinear element is studied.

The paper proposes a method for constructing signal transition graphs (STGs), which are directly mapped into asynchronous circuits for data processing. The advantage of the proposed method is that the resulting circuits are not only output-persistent, but also conformant to the environment. In other approaches, the environment is specified implicitly and/or inexactly and therefore they guarantee only output persistence. The conformation can be verified if both the circuit and its environment are specified by STGs. As an example, we consider a module realizing the function AND2. This module can either wait for both 1s or evaluate the function as soon as at least one 0 arrives. For each case, we draw up a separate STG (scenario) and map it into NCL gates. To provide such a mapping, we specify the behaviors of NCL gates by STG protocols. For data path, such an STG always contains alternative branches with the so-called garbage transitions at the gate inputs. The garbage transitions on a certain wire mean that the circuit is sensitive to the delay in this wire. Ignoring the garbage may lead to a violation of conformation or/and output persistence. For example, in the combinational part of the NCL circuits, the garbage appears on the inputs of NCL gates, and therefore these circuits are not delay insensitive.