A new characterization of finite σ-soluble PσT-groups

Let σ = {σi | i ∈ I} be a partition of the set of all primes ℙ and G a finite group. G is said to be σ-soluble if every chief factor H/K of G is a σᵢ-group for some i = i(H/K). A set H of subgroups of G is said to be a complete Hall σ-set of G if every member ≠ 1 of H is a Hall σᵢ-subgroup of G for...

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1. Verfasser: Adarchenko, N.M.
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Zitieren:A new characterization of finite σ-soluble PσT-groups / N.M. Adarchenko // Algebra and Discrete Mathematics. — 2020. — Vol. 29, № 1. — С. 33–41. — Бібліогр.: 18 назв. — англ.

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spelling irk-123456789-1884992023-03-04T01:27:00Z A new characterization of finite σ-soluble PσT-groups Adarchenko, N.M. Let σ = {σi | i ∈ I} be a partition of the set of all primes ℙ and G a finite group. G is said to be σ-soluble if every chief factor H/K of G is a σᵢ-group for some i = i(H/K). A set H of subgroups of G is said to be a complete Hall σ-set of G if every member ≠ 1 of H is a Hall σᵢ-subgroup of G for some σᵢ∈ σ and H contains exactly one Hall σᵢ-subgroup of G for every i such that σᵢ ∩ π(G) ≠ ∅. A subgroup A of G is said to be σ-quasinormal or σ-permutable in G if G has a complete Hall σ-set H such that AHˣ = HˣA for all x ∈ G and all H ∈ H. We obtain a new characterization of finite σ-soluble groups G in which σ-permutability is a transitive relation in G. 2020 Article A new characterization of finite σ-soluble PσT-groups / N.M. Adarchenko // Algebra and Discrete Mathematics. — 2020. — Vol. 29, № 1. — С. 33–41. — Бібліогр.: 18 назв. — англ. 1726-3255 DOI:10.12958/adm1530 2010 MSC: 20D10, 20D15, 20D30 http://dspace.nbuv.gov.ua/handle/123456789/188499 en Algebra and Discrete Mathematics Інститут прикладної математики і механіки НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
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description Let σ = {σi | i ∈ I} be a partition of the set of all primes ℙ and G a finite group. G is said to be σ-soluble if every chief factor H/K of G is a σᵢ-group for some i = i(H/K). A set H of subgroups of G is said to be a complete Hall σ-set of G if every member ≠ 1 of H is a Hall σᵢ-subgroup of G for some σᵢ∈ σ and H contains exactly one Hall σᵢ-subgroup of G for every i such that σᵢ ∩ π(G) ≠ ∅. A subgroup A of G is said to be σ-quasinormal or σ-permutable in G if G has a complete Hall σ-set H such that AHˣ = HˣA for all x ∈ G and all H ∈ H. We obtain a new characterization of finite σ-soluble groups G in which σ-permutability is a transitive relation in G.
format Article
author Adarchenko, N.M.
spellingShingle Adarchenko, N.M.
A new characterization of finite σ-soluble PσT-groups
Algebra and Discrete Mathematics
author_facet Adarchenko, N.M.
author_sort Adarchenko, N.M.
title A new characterization of finite σ-soluble PσT-groups
title_short A new characterization of finite σ-soluble PσT-groups
title_full A new characterization of finite σ-soluble PσT-groups
title_fullStr A new characterization of finite σ-soluble PσT-groups
title_full_unstemmed A new characterization of finite σ-soluble PσT-groups
title_sort new characterization of finite σ-soluble pσt-groups
publisher Інститут прикладної математики і механіки НАН України
publishDate 2020
url http://dspace.nbuv.gov.ua/handle/123456789/188499
citation_txt A new characterization of finite σ-soluble PσT-groups / N.M. Adarchenko // Algebra and Discrete Mathematics. — 2020. — Vol. 29, № 1. — С. 33–41. — Бібліогр.: 18 назв. — англ.
series Algebra and Discrete Mathematics
work_keys_str_mv AT adarchenkonm anewcharacterizationoffinitessolublepstgroups
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fulltext “adm-n1” — 2020/5/14 — 19:35 — page 33 — #41 © Algebra and Discrete Mathematics RESEARCH ARTICLE Volume 29 (2020). Number 1, pp. 33–41 DOI:10.12958/adm1530 A new characterization of finite σ-soluble PσT -groups N. M. Adarchenko Communicated by L. A. Kurdachenko Abstract. Let σ = {σi | i ∈ I} be a partition of the set of all primes P and G a finite group. G is said to be σ-soluble if every chief factor H/K of G is a σi-group for some i = i(H/K). A set H of subgroups of G is said to be a complete Hall σ-set of G if every member 6= 1 of H is a Hall σi-subgroup of G for some σi ∈ σ and H contains exactly one Hall σi-subgroup of G for every i such that σi ∩ π(G) 6= ∅. A subgroup A of G is said to be σ-quasinormal or σ-permutable in G if G has a complete Hall σ-set H such that AHx = HxA for all x ∈ G and all H ∈ H. We obtain a new characterization of finite σ-soluble groups G in which σ-permutability is a transitive relation in G. 1. Introduction Throughout this paper, all groups are finite and G always denotes a finite group. Moreover, P is the set of all primes, π ⊆ P and π′ = P \ π. The group G is called π-supersoluble provided every chief factor of G is either cyclic or a π′-group. If n is an integer, the symbol π(n) denotes the set of all primes dividing n; as usual, π(G) = π(|G|), the set of all primes dividing the order of G. 2010 MSC: 20D10, 20D15, 20D30. Key words and phrases: finite group, σ-permutable subgroup, PσT -group, σ-soluble group, σ-nilpotent group. https://doi.org/10.12958/adm1530 “adm-n1” — 2020/5/14 — 19:35 — page 34 — #42 34 New characterization of finite σ-soluble PσT -groups In what follows, σ is some partition of P, that is, σ = {σi|i ∈ I}, where P = ⋃ i∈I σi and σi ∩ σj = ∅ for all i 6= j. The symbol σ(n) denotes the set {σi|σi ∩ π(n) 6= ∅}; σ(G) = σ(|G|). The group G is said to be: σ-primary (A.N. Skiba [1]) if G is a σi-group for some i ∈ I; σ-decomposable (L.A. Shemetkov [2]) or σ-nilpotent [3, 4] if G = G1 × · · · ×Gn for some σ-primary groups G1, . . . , Gn; σ-soluble [1] if every chief factor of G is σ-primary. A set H of subgroups of G is a complete Hall σ-set of G [3, 5] if every member 6= 1 of H is a Hall σi-subgroup of G for some σi ∈ σ and H contains exactly one Hall σi-subgroup of G for every σi ∈ σ(G). Let τH(A) = {σi ∈ σ(G) \ σ(A) | σ(A) ∩ σ(HG) 6= ∅ for a Hall σi-subgroup H ∈ H}. Then we say, following Beidleman and Skiba [6], that a subgroup A of G is: (i) τσ-permutable in G with respect to H if AHx = HxA for all x ∈ G and all H ∈ H such that σ(H) ⊆ τH(A); (ii) τσ-permutable in G if A is τσ-permutable in G with respect to some complete Hall σ-set H of G. Recall also that a subgroup A of G is said to be: σ-permutable in G [1] if G possesses a complete Hall σ-set H such that AHx = HxA for all H ∈ H and all x ∈ G; σ-semipermutable in G [7] if G possesses a complete Hall σ-set H such that AHx = HxA for all x ∈ G and all H ∈ H with σ(A) ∩ σ(H) = ∅; σ-subnormal in G [1] if there is a subgroup chain A = A0 6 A1 6 · · · 6 At = G such that either Ai−1 E Ai or Ai/(Ai−1)Ai is σ-primary for all i = 1, . . . , t. In the classical case when σ = σ1 = {{2}, {3}, . . .} (we use here the notations in [3]), σ-permutable, σ-semipermutable and τσ-quasinormal subgroups are also called respectively S-permutable [8], S-semipermutable [9] and τ -permutable [10,11], and in this case σ-subnormal subgroups are exactly subnormal subgroups of the group. It is clear that every σ-permutable subgroup is also σ-semipermutable and every σ-semipermutable subgroup is τσ-permutable. Recall also that G is said to be a PσT -group [1] if σ-permutability is a transitive relation in G, that is, if H is a σ-permutable subgroup of K and K is a σ-permutable subgroup of G, then H is σ-permutable in G. In the case when σ = σ1, a PσT -group is called a PST -group [8]. In view of Theorem B in [1], PσT -groups can be characterized as the groups in which every σ-subnormal subgroup is σ-permutable. Another characterizations of PσT -groups are obtained in the papers [3, 7, 12–14]. “adm-n1” — 2020/5/14 — 19:35 — page 35 — #43 N. M. Adarchenko 35 Our main goal here is to give a characterization of PσT -groups in the terms of τσ-permutable subgroups. Theorem 1.1. Let D = GNσ and π = π(D). Suppose that G possesses a complete σ-set H all members of which are π-supersoluble. Then G is a σ- soluble PσT -group if and only if every σi-subgroup of G is τσ-permutable in G for all σi ∈ σ(D). In this theorem the symbol GNσ denotes the σ-nilpotent residual of G, that is, the intersection of all normal subgroups N of G with σ-nilpotent quotient G/N ; GN is the nilpotent residual of G. Corollary 1.1 (see Theorem A in [7]). Let D = GNσ and π = π(D). Suppose G possesses a complete Hall σ-set H all members of which are π-supersoluble. If every σi-subgroup of G is σ-semipermutable in G for all σi ∈ σ(D), then G is a σ-soluble PσT -group. As another application of Theorem 1.1, we give the following new characterization of soluble PST -groups. Corollary 1.2. G is a soluble PST -group if and only if every subgroup of every Sylow p-subgroup of G is τ -semipermutable in G for all p ∈ π(GN). All unexplained notation and terminology are standard. The reader is referred to [8], [15] or [16] if necessary. 2. Preliminaries We use Nσ to denote the class of all σ-nilpotent groups. Lemma 2.1 (see Lemma 2.5 in [1]). The class Nσ is closed under taking direct products, homomorphic images and subgroups. Moreover, if E is a normal subgroup of G and E/E ∩ Φ(G) is σ-nilpotent, then E is σ- nilpotent. In view of Proposition 2.2.8 in [16], we get from Lemma 2.1 the following Lemma 2.2. If N is a normal subgroup of G, then (G/N)Nσ = GNσN/N. “adm-n1” — 2020/5/14 — 19:35 — page 36 — #44 36 New characterization of finite σ-soluble PσT -groups Lemma 2.3 (V. N. Knyagina and V. S. Monakhov [17]). Let H, K and N be pairwise permutable subgroups of G and H a Hall subgroup of G. Then N ∩HK = (N ∩H)(N ∩K). Recall that G is said to be: a Dπ-group if G possesses a Hall π-subgroup E and every π-subgroup of G is contained in some conjugate of E; a σ-full group of Sylow type [1] if every subgroup E of G is a Dσi -group for every σi ∈ σ(E); σ-full [5] provided G possesses a complete Hall σ-set. In view of Theorems A and B in [5], the following fact is true. Lemma 2.4. If G is σ-soluble, then G is a σ-full group of Sylow type. Lemma 2.5 (see Lemma 3.1 in [1]). Let H be a σi-subgroup of a σ-full group G. Then H is σ-permutable in G if and only if Oσi(G) 6 NG(H). Lemma 2.6. Suppose that G is σ-full and D := GNσ is a nilpotent Hall subgroup of G. If every σi-subgroup of G is τσ-permutable in G for all σi ∈ σ(D), then every subgroup of D is normal in G. Proof. Suppose that this lemma is false and let G be a counterexam- ple of minimal order. By hypothesis, G possesses a complete Hall σ-set {H1, . . . , Ht}. We can assume without loss of generality that Hi is a σi- group for all i = 1, . . . , t. First we show that the hypothesis holds on G/N for every minimal normal subgroup N of G. First note that (G/N)Nσ = DN/N ≃ D/(D ∩N) is a nilpotent Hall subgroup of G/N by Lemma 2.2. Now let V/N be a non-identity σi-subgroup of G/N for some σi ∈ σ((G/N)Nσ) = σ(DN/N) = σ(D/(D ∩N)) ⊆ σ(D). And let U be a minimal supplement to N in V . Then U ∩N 6 Φ(U), so U is a σi-subgroup of G since V/N = UN/N ≃ U/(U ∩ N). Therefore U is τσ-permutable in G by hypothesis and σ(U) = σ(UN/N) = {σi}, which implies that V/N = UN/N is τσ-quasinormal in G/N by Lemma 2.6(1) in [6]. Hence the hypothesis holds on G/N . Now let H be a subgroup of the Sylow p-subgroup P of D for some prime p ∈ π. We show that H is normal in G. For some i we have P 6 Oσi (D) = Hi∩D. On the other hand, we have D = Oσi (D)×Oσi(D) “adm-n1” — 2020/5/14 — 19:35 — page 37 — #45 N. M. Adarchenko 37 since D is nilpotent. Assume that Oσi(D) 6= 1 and let N be a minimal normal subgroup of G contained in Oσi(D). Then HN/N 6 DN/N = (G/N)Nσ , so the choice of G implies that HN/N is normal in G/N . Hence H = H(N ∩Oσi (D)) = HN ∩Oσi (D) is normal in G. Now assume that Oσi(D) = 1, so D is a σi-group. Since G/D is σ-nilpotent by Lemma 2.1, Hi/D is normal in G/D and hence Hi is normal in G. Therefore all subgroups of Hi are σ-permutable in G by Lemma 2.6(3) in [6] and hypothesis. Since D is a normal Hall subgroup of Hi, it has a complement S in Hi by the Schur-Zassenhaus theorem. Lemma 2.5 implies that D 6 Oσi(G) 6 NG(S). Hence Hi = D×S. Hence S 6 NG(H), so G = HiO σi(G) = (SD)Oσi(G) = SOσi(G) 6 NG(H), so H is normal in G. Therefore every subgroup of D is normal in G since D is nilpotent by hypothesis. The lemma is proved. Lemma 2.7 (see Theorem A in [3]). Let D = GNσ . If G is a σ-soluble PσT -group, then the following conditions hold: (i) G = D ⋊ M , where D is an abelian Hall subgroup of G of odd order, M is σ-nilpotent and every element of G induces a power automorphism in D; (ii) Oσi (D) has a normal complement in a Hall σi-subgroup of G for all i. Conversely, if Conditions (i) and (ii) hold for some subgroups D and M of G, then G is a PσT -group. Lemma 2.8 (see Theorem A in [3]). The following statements hold: (1) G is a PσT -group if and only if every σ-subnormal subgroup of G is σ-permutable in G; (2) If G is a σ-soluble PσT -group, then every quotient G/N of G is also a σ-soluble PσT -group. 3. Proof of Theorem 1.1 Let H = {H1, . . . , Ht}. We can assume without loss of generality that Hi is a σi-group for all i = 1, . . . , t. First show that if every σi-subgroup of G is τσ-permutable in G for all σi ∈ σ(D), then G is a σ-soluble PσT -group. Assume that this is false and let G be a counterexample of minimal order. “adm-n1” — 2020/5/14 — 19:35 — page 38 — #46 38 New characterization of finite σ-soluble PσT -groups (1) G = D⋊M , where D is an abelian Hall subgroup of G of odd order, M is σ-nilpotent and every element of G induces a power automorphism in D (this claim directly follows from Lemma 2.6 and Theorem 1.5 in [18]). (2) If R is a non-identity normal subgroup of G, then the hypothesis holds for G/R, so G/R is a σ-soluble PσT -group. First note that H0 = {H1N/N, . . . ,HtN/N} is a complete Hall σ-set of G/N . Moreover, every member HiN/N ≃ Hi/(Hi∩N) of H0 is π-supersoluble since Hi is π-supersoluble by hypoth- esis. On the other hand, (G/N)Nσ = DN/N ≃ D/(D ∩ N) by Lemma 2.2. Hence π0 ⊆ π, where π0 = π((G/N)Nσ), so every member of H0 is π0-supersoluble. Let V/N be a non-identity σi-subgroup of G/N for some σi ∈ σ((G/N)Nσ) = σ(DN/N) = σ(D/D ∩N) ⊆ σ(D). And let U be a minimal supplement to N in V . Then U ∩N 6 Φ(U), so U is a σi-subgroup of G by the isomorphism V/N = UN/N ≃ U/U ∩N . Therefore U is τσ-permutable in G by hypothesis and σ(U) = σ(UN/N) = {σi}, which implies that V/N = UN/N is τσ-permutable in G/N by Lemma 2.6(1) in [6]. Hence the hypothesis holds on G/N , so the choice of G implies that G/N is a σ-soluble PσT -group. (3) Hi = Oσi (D)× S for some subgroup S of Hi for each σi ∈ σ(D). Since D is a nilpotent Hall subgroup of G by Claim (1), D = L×N , where L = Oσi (D) and N = Oσi(D) are Hall subgroups of G. First assume that N 6= 1. Then Oσi ((G/N)Nσ) = Oσi (D/N) = LN/N has a normal complement V/N in HiN/N ≃ Hi by Claim (2). On the other hand, N has a complement S in V by the Schur-Zassenhaus theorem. Hence Hi = Hi ∩ LSN = LS and L ∩ S = 1 since (L ∩ S)N/N 6 (LN/N) ∩ (V/N) = (LN/N) ∩ (SN/N) = 1. It is clear that V/N is a Hall subgroup of HiN/N , so V/N is characteristic in HiN/N . On the other hand, HiN/N is normal in G/N by Lemma 2.2 “adm-n1” — 2020/5/14 — 19:35 — page 39 — #47 N. M. Adarchenko 39 since D/N 6 HiN/N . Hence V/N is normal in G/N . Thus Hi ∩ V = Hi ∩NS = S(Hi ∩N) = S is normal in Hi, so Hi = Oσi (D)× S. Now assume that D = Oσi (D). Then Hi is normal in G, so all sub- groups of Hi are σ-permutable in G by Lemma 2.6(3) in [6]. Since D is a normal Hall subgroup of Hi, it has a complement S in Hi. Lemma 2.5 implies that D 6 Oσi(G) 6 NG(S). Hence Hi = D × S = Oσi (D)× S. Now, from Lemma 2.7 and Claims (2) and (3) it follows that G is a σ-soluble PσT -group, contrary our assumption on the G. This completes the proof of the sufficiency of the condition of the theorem. Now we show that if G is a σ-soluble PσT -group, then every σi- subgroup of G is τσ-permutable in G for each σi ∈ σ(D). It is enough to show that H is a σi-subgroup of G, then H permutes with every Hall σj-subgroups of G for all j 6= i. Assume that this is false and let G be a counterexample of minimal order. Then D 6= 1 and there are σi and σj (i 6= j) such that σi ∈ σ(D) and HE 6= EH for some σi-subgroup H and some Hall σj-subgroup E of G. Then H is not σ-subnormal in G by Lemma 2.8. Hence a Hall σi-subgroup Hi of G is not normal in G since otherwise we have H 6 Hi and so H is σ-subnormal in G by Lemma 2.6(6) in [1]. Now note that |σ(D)| > 1, Indeed, if |σ(D)| = 1, then σ(D) = {σi} and so D 6 Hi, which implies that Hi/D is normal in G/D since G/D is σ-nilpotent by Lemma 2.1. But then Hi is normal in G, a contradiction. Now we show that EHN is a subgroup of G for every minimal normal subgroup N of G. First note that the hypothesis holds for G/N by Lemma 2.8. Moreover, HN/N ≃ H/H ∩N is a σi-subgroup of G/N . Therefore, if σi ∈ σ(DN/N) = σ((G/N)Nσ), then the choice of G implies that (HN/N)(EN/N) = (EN/N)(HN/N) = EHN/N is a subgroup of G/N . Hence EHN is a subgroup of G. Now assume that σi 6∈ σ(DN/N). Then a Hall σi-subgroup Hi of G is contained in N , so Hi = N since N is σ-primary. But then H 6 N and so H is σ-subnormal in G, a contradiction. Hence EHN is a subgroup of G. Since |σ(D)| > 1 and D is abelian by Lemma 2.7, G has at least two σ-primary minimal normal subgroups R and N such that R,N 6 D and σ(R) 6= σ(N). Then at least one of the subgroups R or N , R say, is a σk-group for some k 6= j. Moreover, R ∩ E(HN) = (R ∩ E)(R ∩HN) = R ∩HN “adm-n1” — 2020/5/14 — 19:35 — page 40 — #48 40 New characterization of finite σ-soluble PσT -groups by Lemma 2.3 and R ∩ HN 6 Oσk (HN) 6 V , where V is a Hall σk- subgroup of H, since N is a σ′ k-group and G is a σ-full group of Sylow type by Lemma 2.1. Hence EHR ∩ EHN = E(HR ∩ EHN) = EH(R ∩ E(HN)) = EH(R ∩HN) = EH(R ∩H) = EH is a subgroup of G. Hence HE = EH. This contradicts the fact that HE 6= EH. The necessity of the condition of the theorem is proved. The theorem is proved. References [1] A.N. Skiba, On σ-subnormal and σ-permutable subgroups of finite groups, J. Algebra, 436 (2015), 1–16. [2] L.A. Shemetkov, Formations of Finite Groups, Nauka, Moscow, 1978. [3] A.N. Skiba, Some characterizations of finite σ-soluble PσT -groups, J. Algebra, 495(1) (2018), 114–129. [4] W. Guo, A.N. Skiba, On σ-supersoluble groups and one generalization of CLT - groups, J. Algebra, 512 (2018), 92–108. [5] A.N. Skiba, A generalization of a Hall theorem, J. Algebra and its Application, 15(4) (2015), 21–36. [6] J.C. Beidleman, A.N. Skiba, On τσ-quasinormal subgroups of finite groups, J. Group Theory, 20(5) (2017), 955–964. [7] B. Hu, J. Huang, A.N. Skiba, Finite groups with given systems of σ-semipermutable subgroups, J. Algebra and its Application, 17(2) (2018), 1850031 (13 pages), DOI:10.1142/S0219498818500317. [8] A. Ballester-Bolinches, R. Esteban-Romero, M. Asaad, Products of Finite Groups, Walter de Gruyter, Berlin-New York, 2010. [9] W. Guo, Structure Theory for Canonical Classes of Finite Groups, Springer, Heidelberg-New York-Dordrecht-London, 2015. [10] V.O. Lukyanenko, A.N. Skiba, On weakly τ -quasinormal subgroups of finite groups, Acta Math. Hungar., 125(3) (2009), 237–248. [11] V.O. Lukyanenko, A.N. Skiba, Finite groups in which τ -quasinormality is a tran- sitive relation, Rend. Sem. Mat. Univ. Padova, 124 (2010), 1–15. [12] A.N. Skiba, On some classes of sublattices of the subgroup lattice, J. Belarusian State Univ. Math. Informatics, 3 (2019), 35–47. [13] Z. Chi, A.N. Skiba, On a lattice characterization of finite soluble PST -groups, Bull. Austral. Math. Soc., (2019), DOI:10.1017/S0004972719000741. [14] A.N. Skiba, On sublattices of the subgroup lattice defined by formation Fitting setsJ. Algebra, (in Press), doi.org/10.1016/j.jalgebra.2019.12.013. “adm-n1” — 2020/5/14 — 19:35 — page 41 — #49 N. M. Adarchenko 41 [15] K. Doerk, T. Hawkes, Finite soluble groups, Walter de Gruyter, Berlin–New York, 1992. [16] A. Ballester-Bolinches, L.M. Ezquerro, Classes of Finite Groups, Springer-Verlag, Dordrecht, 2006. [17] B.N. Knyagina, V.S. Monakhov, On π ′-properties of finite groups having a Hall π-subgroup, Siberian Math. J., 522 (2011), 398–309. [18] N.M. Adarchenko, On τσ-permutable subgroups of finite groups, Preprint, 2019. Contact information Nikita M. Adarchenko Department of Mathematics and Technologies of Programming, Francisk Skorina Gomel State University, Gomel 246019, Belarus E-Mail(s): nik.adarchenko@gmail.com Received by the editors: 20.01.2020. N. M. Adarchenko