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Homomorphisms from infinite semilcyclic n-groups to a semiabelian n-group
N. A. Shchuchkin Volgograd
State Socio-Pedagogical University (Volgograd)
Abstract:
One of the main problems for semiabelian n-groups is the finding of semiabelian n-groups, which are isomorphic to (n)-groups of homomorphisms from certain n-groups to a semiabelian n-group. Such n-groups are found for infinite semicyclic n-groups.
It is known that the set Hom(G,C) of all homomorphisms from n-groups ⟨G,f1⟩ to a semiabelian (abelian) n-group ⟨C,f2⟩ with n-ary operation g given by the rule g(φ1,…,φn)(x)=f2(φ1(x),…,φn(x)),x∈G, forms a semiabelian (abelian) n-group. It is proved that the isomorphisms ψ1 of n-groups ⟨G,f1⟩ and ⟨G′,f′1⟩ and psi2 of semiabelian n-groups ⟨C,f2⟩ and ⟨C′,f′2⟩ induce an isomorphism τ of n-groups of homomorphisms ⟨Hom(G,C),g⟩ and ⟨Hom(G′,C′),g′⟩, which acts according to the rule τ:α→ψ2∘α∘ψ−11.
On the additive group of integers Z we construct an abelian n-group ⟨Z,f1⟩ with n-ary operation f1(z1,…,zn)=z1+…+zn+l, where l is any integer. For a nonidentical automorphism φ(z)=−z on Z, we can specify semiabelian n-group ⟨Z,f2⟩ for n=2k+1, k∈N, with the n-ary operation f2(z1,…,zn)=z1−z2+…+z2k−1−z2k+z2k+1. Any infinite semicyclic n-group is isomorphic to either the n-group ⟨Z,f1⟩, where 0≤l≤[n−12], or the n-group ⟨Z,f2⟩ for odd n. In the first case we will say that such n-group has type (∞,1,l), and in the second case, it has type (∞,−1,0).
In studying the n-groups of homomorphisms ⟨Hom(Z,C),g⟩ from an infinite abelian semicyclic n-group ⟨Z,f1⟩ (0≤l≤n−12) to a semiabelian n-group ⟨C,f2⟩ we construct on the n-group ⟨C,f2⟩ an abelian group C with the addition operation a+b=f2(a,(n−3)c,ˉc,b), in which there is an element d2=f2((n)c) and an automorphism φ2(x)=f2(c,x,(n−3)c,ˉc). Choose a set P1 of such ordered pairs (a,u) of elements from C that satisfy the equality la=d2+∼φ2(u), where ∼φ2(x)=x+φ2(x)+…+φn−22(x),x∈C is an endomorphism of the group C, and for the first component of these pairs the equality is true φ2(a)=a. On this set, we define a n-ary operation h1 by the rule h1((a1,u1),…,(an,un))=(a1+…+an,f2(u1,…,un)). It is proved that ⟨P1,h1⟩ is a semiabelian n-group, which is isomorphic to the n-group of homomorphisms from an infinite abelian semicyclic n-group ⟨Z,f1⟩ (0≤l≤n−12) to an n-group ⟨C,f2⟩. The consequence of this isomorphism is an isomorphism of n-groups of ⟨P1,h1⟩ and n-groups of homomorphisms from an infinite abelian semicyclic n-group of type (∞,1,l) to a semiabelian n-group ⟨C,f2⟩.
When studying the n-group of homomorphisms ⟨Hom(Z,C),g⟩ from the infinite semicyclic n-group ⟨Z,f′1⟩ to the semiabelian n-group ⟨C,f2⟩ in the abelian group C choose the subgroup H={a∈C | φ2(a)=−a}. On H we define a semiabelian n-group ⟨H,h⟩, where h acts according to the rule h(a1,a2,…,an−1,an)=a1+φ2(a2)+…+φn−22(an−1)+an. Then in the n-group ⟨C,f2⟩ we select the subgroup ⟨T,f2⟩ of all idempotents, if T≠∅. It is proved that for an odd number n>1 a direct product of semiabelian n-groups ⟨H,h⟩×⟨T,f2⟩ is isomorphic to n-group of homomorphisms from infinite semicyclic n-groups of ⟨Z,f′1⟩ to a semiabelian n-group ⟨C,f2⟩ with a non empty set of idempotents T. The consequence of this isomorphism is the isomorphism of the n-group ⟨H,h⟩×⟨T,f2⟩ and n-groups of homomorphisms from an infinite semicyclic n-group of type (∞,−1,0) to the semiabelian n-group ⟨C,f2⟩.
Similar facts were obtained when studying the n-group of homomorphisms ⟨Hom(Z,C),g⟩ from n-groups ⟨Z,f1⟩ and ⟨Z,f′1⟩ to an abelian n-group ⟨C,f2⟩.
Keywords:
n-group, semiabelian (n,2)-group, abelian (n,2)-group, homomorphism.
Received: 12.11.2020 Accepted: 21.02.2021
Citation:
N. A. Shchuchkin, “Homomorphisms from infinite semilcyclic n-groups to a semiabelian n-group”, Chebyshevskii Sb., 22:1 (2021), 340–352
Linking options:
https://www.mathnet.ru/eng/cheb1005 https://www.mathnet.ru/eng/cheb/v22/i1/p340
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Abstract page: | 144 | Full-text PDF : | 45 | References: | 32 |
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