<p>We study Hasse–Schmidt (higher) derivations on associative <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\mathbb {Z}_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">Z</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>-graded algebras (superalgebras), requiring each component to preserve the <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\mathbb {Z}_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="double-struck">Z</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>-grading. We establish the group structure under the shuffle product, characterise inner Hasse–Schmidt derivations, and identify a degree-parity obstruction that renders the odd-degree theory trivial on prime superalgebras. In the prime setting we prove: (i)&#xa0;a Posner-type theorem showing that a non-zero centralising Hasse–Schmidt derivation forces the even part <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mathcal {A}_0\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">A</mi> <mn>0</mn> </msub> </math></EquationSource> </InlineEquation> to be commutative—a conclusion specific to the graded setting; (ii)&#xa0;a nilpotency theorem; and (iii)&#xa0;a structure theorem via the Martindale quotient ring. We show that every Jordan Hasse–Schmidt derivation on a 2-torsion-free prime superalgebra with non-commutative even part is a genuine Hasse–Schmidt derivation. For semiprime superalgebras we establish uniqueness of extension and commutativity criteria. Explicit examples and sharpness counterexamples are provided.</p>

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Hasse–Schmidt derivations on prime and semiprime associative superalgebras

  • Saïd Belkadi

摘要

We study Hasse–Schmidt (higher) derivations on associative \(\mathbb {Z}_2\) Z 2 -graded algebras (superalgebras), requiring each component to preserve the \(\mathbb {Z}_2\) Z 2 -grading. We establish the group structure under the shuffle product, characterise inner Hasse–Schmidt derivations, and identify a degree-parity obstruction that renders the odd-degree theory trivial on prime superalgebras. In the prime setting we prove: (i) a Posner-type theorem showing that a non-zero centralising Hasse–Schmidt derivation forces the even part \(\mathcal {A}_0\) A 0 to be commutative—a conclusion specific to the graded setting; (ii) a nilpotency theorem; and (iii) a structure theorem via the Martindale quotient ring. We show that every Jordan Hasse–Schmidt derivation on a 2-torsion-free prime superalgebra with non-commutative even part is a genuine Hasse–Schmidt derivation. For semiprime superalgebras we establish uniqueness of extension and commutativity criteria. Explicit examples and sharpness counterexamples are provided.