539 Another possibility considered here was ``pivotal $n$-category", but we prefer to preserve pivotal for its usual sense. 

   539 Another possibility considered here was ``pivotal $n$-category", but we prefer to preserve pivotal for its usual sense. 

   540 It will thus be a theorem that our disk-like 2-categories 

   540 It will thus be a theorem that our disk-like 2-categories 

   541 are equivalent to pivotal 2-categories, c.f. \S \ref{ssec:2-cats}.

   541 are equivalent to pivotal 2-categories, c.f. \S \ref{ssec:2-cats}.

   542 

   542 

   543 Finally, we need a general name for isomorphisms between balls, where the balls could be

   543 Finally, we need a general name for isomorphisms between balls, where the balls could be

   545 We have chosen to use ``homeomorphism" for the appropriate sort of isomorphism, so the reader should

   545 We have chosen to use ``homeomorphism" for the appropriate sort of isomorphism, so the reader should

   546 keep in mind that ``homeomorphism" could mean PL homeomorphism or diffeomorphism (and so on)

   546 keep in mind that ``homeomorphism" could mean PL homeomorphism or diffeomorphism (and so on)

   547 depending on context.

   547 depending on context.

   548 

   548 

   549 \subsection{Thanks and acknowledgements}

   549 \subsection{Thanks and acknowledgements}