Good eye, this was fixed in the manuscript a while ago. I will ping Manning to re-publish Chapters 1-6 since a lot of small updates have happened since then.
On Fri, Apr 23, 2010 at 4:53 PM, Jeff Eastman <j...@windwardsolutions.com> wrote: > Section 4.5.1 says: > "The third line shows how it is based on item-item similarities, not > user-user similarities as before. The algorithms are similar, but not > entirely symmetric. They do have notably different properties. For instance, > the running time of an item-based recommender scales up as the number of > items increases, whereas a user-based recommender’s running time goes up as > the number of users increases. > > This suggests one reason that you might choose an item-based recommender: if > the number of users is relatively low compared to the number of items, the > performance advantage could be significant." > > Shouldn't the second paragraph be? > > "This suggests one reason that you might choose an item-based recommender: > if the number of users is relatively *high* compared to the number of items, > the performance advantage could be significant." > >
