algebraic_brain pointed me to the latest paper on n-category cafe, namely Baez, Hoffnung, Walker's "Groupoidification Made Easy", a really exciting paper. I heard about this cardinality-of-groupoids thing before occasionally, but it's starting to actually sink in. algebraic_brain pointed me to the latest paper on n-category cafe, namely Baez, Hoffnung, Walker's "Groupoidification Made Easy", a really exciting paper. I heard about this cardinality-of-groupoids thing before occasionally, but it's starting to actually sink in.