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M. Rybakov

Publications and source records attributed to M. Rybakov.

9 recordsLinked to original sources

Analysis of some solid amorphous inorganic structures and the boson peak phenomenon with a computational random graph approach

In this study, a new alternative model algorithm has been proposed for assembling amorphous structures, unifying the bosonic paradigm applicable at low temperatures with crystalline models relevant at room and higher temperatures. Physical meaning of main model parameters is determined together with an explanation for the appearing bosonic peak using the random graph theory. Numerically, statistical atomic distribution in a multiphase amorphous system is provided without the melting simulation of base crystals, and the mean energy function has been determined analytically. The calculated table data are in good agreement with neutronography measurements of the actual amorphous alloy in its solid state. Programme optimisations were also implemented, and we outlined several effective steps to achieve the higher processing speed. The proposed programme code can be used for potential test assembling and simulations of amorphous systems with sorting by the optimal atomic content or proportion (i.e. glass forming ability).

cond-mat.mtrl-sci

Logics with the axiom of convergence: complexity with a small number of variables in the language (extended version)

It is known that many modal and superintuitionistic logics are PSPACE-hard in languages with a small number of variables; however, questions about the complexity of similar fragments of many logics obtained by adding various axioms to "standard" ones remain unexplored. We investigate the complexity of fragments of modal logics obtained by adding an axiom requiring the convergence of the accessibility relation in Kripke frames: S4.2, K4.2, Grz.2, and GL.2. The main result is that S4.2 and Grz.2 are PSPACE-complete in a language with two variables, while K4.2 and GL.2* (a logic near to GL.2) are PSPACE-complete in a language with one variable. The obtained results are extended to infinite classes of logics.

math.LO

Algorithmic properties of QK4.3 and QS4.3

We prove that predicate modal logics QK4.3 and QS4.3 are undecidable in languages with two individual variables, one modandic predicate letter, and one proposition letter.

math.LO

Computational complexity of one-variable fragments of products with T

We show that products of propositional modal logics containing the logic of reflexive frames T as a factor are embeddable into their single-variable fragments. The proof is a simplified version of the proof, to appear, of a similar result for products and expanding relativized products containing as a factor the logic KTB of reflexive and symmetric Kripke frames.

math.LO