Multiplicativity of Connes' calculus
Reviews in Mathematical Physics
In his book on noncommutative geometry, Connes constructed a differential graded algebra out of a spectral triple. Lack of monoidality of this construction is investigated. We identify a suitable monoidal subcategory of the category of spectral triples and show that when restricted to this subcategory the construction of Connes is monoidal. Richness of this subcategory is exhibited by establishing a faithful endofunctor to this subcategory.
Chakraborty, Partha Sarathi and Guin, Satyajit, "Multiplicativity of Connes' calculus" (2019). Journal Articles. 682.