Nijenhuis operators and mock-Lie bialgebras
Tianshui Ma, Sami Mabrouk, Abdenacer Makhlouf, Feiyan Song
TL;DR
The paper develops a comprehensive framework for Nijenhuis operators on mock-Lie algebras, extending to mock-Lie bialgebras and establishing a parallel theory of deformations, abelian extensions, and cohomology. It introduces Nijenhuis mock-Lie algebras and connects them to bialgebra structures through symplectic, dual-quasitriangular, and Manin-triple constructions, culminating in a coboundary theory via the mock-Lie Yang–Baxter equation. Central contributions include the characterization of Nijenhuis mock-Lie bialgebras via matched pairs and Manin triples, the coboundary theory with antisymmetric $r$-matrices, and the role of $ O$-operators as a unifying tool. The results provide a cohesive, cohomology-driven approach to deformations, extensions, and integrable structures in the mock-Lie setting, with potential applications to related non-associative and Jordan-like algebras. The formalism paves the way for further exploration of Loday-type cohomology, Rota–Baxter-like operators, and Yang–Baxter-type equations in nonassociative contexts.
Abstract
A Nijenhuis mock-Lie algebra is a mock-Lie algebra equipped with a Nijenhuis operator. The purpose of this paper is to extend the well-known results about Nijenhuis mock-Lie algebras to the realm of mock-Lie bialgebras. It aims to characterize Nijenhuis mock-Lie bialgebras by generalizing the concepts of matched pairs and Manin triples of mock-Lie algebras to the context of Nijenhuis mock-Lie algebras. Moreover, we discuss formal deformation theory and explore infinitesimal formal deformations of Nijenhuis mock-Lie algebras, demonstrating that the associated cohomology corresponds to a deformation cohomology. Moreover, we define abelian extensions of Nijenhuis mock-Lie algebras and show that equivalence classes of such extensions are linked to cohomology groups. The coboundary case leads to the introduction of an admissible mock-Lie-Yang-Baxter equation (mLYBe) in Nijenhuis mock-Lie algebras, for which the antisymmetric solutions give rise to Nijenhuis mock-Lie bialgebras. Furthermore, the notion of $\mathcal O$-operator on Nijenhuis mock-Lie algebras is introduced and connected to mock-Lie-Yang-Baxter equation.
