This is definitely true and in a few very sparse problems, these might even be usable recommendations.
In general, having some cooccurrence is a useful heuristic. If you find it useful, you can replace the candidate strategy. A good example of an SVD-like algorithm that could produce strong recommendations with no-cooccurrence, see here: http://arxiv.org/abs/1006.2156 We don't much support side information in Mahout so this the candidate set problem associated with these models isn't an issue yet, but at some point using these models might be good. The primary benefit would be better performance in cold-start situations. On Sun, Aug 15, 2010 at 11:18 AM, Tamas Jambor <[email protected]> wrote: > On 15/08/2010 18:29, Sebastian Schelter wrote: > >> What talk about is actually not a bug, if there are no co-rated items >> it's absolutely logical that nothing can be recommended. In a real world >> application you would maybe want to show the user the latest or overall >> top-rated items as a workaround (just to show them something). >> >> > > Thanks, it's true for neighbourhood based algorithms, but SVD could still > give you results. > > Tamas >
