# Questions tagged [ra.rings-and-algebras]

Non-commutative rings and algebras, non-associative algebras, universal algebra and lattice theory, linear algebra, semigroups. For questions specific to commutative algebra (that is, rings that are assumed both associative and commutative), rather use the tag ac.commutative-algebra.

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### About extending maps to semi derivations

Let consider a map $d: X \to P$, where $X$ is a generating set of $P$ and $(P,\cdot, \{,\})$ is a free Poisson algebra. How can we extend $d$ to a semi derivation map from a subalgebra $P$ to $P$? By ...
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### Example of a secondary representation of a module that is not a direct sum

Let $A$ be a commutative ring. An $A$-module $M$ is said to be secondary if $M\neq 0$ and for each $a\in A$, the endomorphism $\phi_a:M\to M$ defined by $\phi_a(m)=am$ for $m\in M$ is either ...
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### Exponential order of unipotent elements in an endomorphism ring of abelian groups

$\DeclareMathOperator\End{End}\newcommand{\Id}{\mathrm{Id}}$Let $E=\End(I)$ be the endomorphism ring of the abelian group $I$. We have the following statement for $B\in E$, $p$ a prime number and $r$ ...
• 95
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