Multiple Rota-Baxter algebra and multiple Rota-Baxter modules
Jun He, Xiaosong Peng, Yi Zhang
TL;DR
This work develops a comprehensive framework for multiple Rota-Baxter structures by introducing left, right, and bimodule MRB modules over a multi-operator algebra $(R,P_{\Omega})$ with pair weight $(\lambda_{\Omega},\lambda_{\Omega})$, and by formalizing the theory of free, projective, injective, and flat MRB modules. It constructs free MRB modules via $\Omega$-operated modules and imposes relations to enforce MRB identities, establishing universal properties and conditions for freeness; it further extends to restricted free modules using MC$(M)$ and demonstrates isomorphisms with standard free modules in singleton cases. The paper develops a Hom functor $\mathrm{Hom}_{(R,P_{\Omega})}$, proves the category has enough projectives and injectives, and introduces the ring of multiple Rota-Baxter operators $R_{MRB}\langle Q_{\Omega}\rangle$ to relate MRB-modules to module categories over this ring. A tensor product over MRB algebras is defined with a universal property, and flatness is established by showing that free and projective MRB-modules are flat and that tensoring preserves exact sequences. Overall, the results equip multi-operator Rota-Baxter theory with a robust homological toolkit, enabling derived functors, tensorial constructions, and flatness theory in a multi-operator setting.
Abstract
In this paper, we develop the theory of multiple Rota-Baxter modules over multiple Rota-Baxter algebras. We introduce left, right, and bimodule structures and construct free $Ω$-operated modules with mixable tensor establishing free commutative multiple Rota-Baxter modules. We provide a necessary and sufficient condition for a free module to admit a free multiple Rota-Baxter module structure. Furthermore, we define projective and injective multiple Rota-Baxter modules, showing that their category has enough projective and injective objects to support derived $\mathrm{Hom}$ functors. Finally, we introduce the tensor product of multiple Rota-Baxter algebras and define flat multiple Rota-Baxter modules, proving that both free and projective modules satisfy the flatness property.
