Re: Skeleton of a category

Would you let me know when the category has an equivalent skeleton?

"every small category has a skeleton" iff the axiom of choice holds. See Exercise 3.26 in my book, or http://www.dcs.qmw.ac.uk/~pt/book/html/s3e.html#e3.26 for a preorder example. Exercise 4.37 defines "skeletal" http://www.dcs.qmw.ac.uk/~pt/book/html/s4e.html#e4.37 Paul