2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/159541The paper explores some algebraic constructions arising in the theory of Lefschetz fibrations. Specifically, it covers in a fair amount of detail the algebraic issues outlined in ``Symplectic homology as Hochschild homology'' (math.SG/0609037). We also explain how the theory works when applied to a simple example, namely the Landau-Ginzburg mirror of P^2. Version 2: revised, many technical assumptions dropped, statement of one of the main results improved by using dg quotients. I changed the title accordingly.K-Theory and HomologyRings and AlgebrasSymplectic Geometrytext