Bialgebra theory for nearly associative algebras and LR-algebras: Equivalence, characterization, and LR-Yang-Baxter equation

We develop the bialgebra theory for two classes of non-associative algebras: nearly associative algebras and LR-algebras. In particular, building on recent studies that reveal connections between these algebraic structures, we establish that nearly associative bialgebras and LR-bialgebras are, in fact, equivalent concepts. We also provide a characterization of these bialgebra classes based on the coproduct. Moreover, since the development of nearly associative bialgebras — and by extension, LR-bialgebras — requires the framework of nearly associative L-algebras, we introduce this class of non-associative algebras and explore their fundamental properties. Furthermore, we identify and characterize a special class of nearly associative bialgebras, the coboundary nearly associative bialgebras, which provides a natural framework for studying the Yang-Baxter equation (YBE) within this context.