[yblu]

Thanks for sharing. What do you mean by the "cold-start" problem? Just want to know exactly when I can use your engines.

[elwell]

Just speculating: not having a recommendation when you first begin because you don't have any data.

[mck-]

Exactly right. I borrowed that term from Chapter 2 on Collective Intelligence [1]

[1] http://shop.oreilly.com/product/9780596529321.do