A Morphism Double Category and Monoidal Structure
  A double category is constructed from a `fattened' version of a given category, motivated in part by a context of parallel transport. We also study monoidal structures on the underlying category and on the fattened category. 
Saikat Chatterjee, Amitabha Lahiri, and Ambar N. Sengupta
math-ph math.CT math.MP