Does Google just sort results by relevance or can Knol be irrelevant but still nr1?

(Maybe this type of post is not for hacker news since it is pure discussion).

Knol.

Does Google promise that their search results are always sorted by relevance or would it be ok to list Knol - entries as top results without them actually being so?

I guess since they obv know how to SEO to their own algorhitm they can make Knol have a high PageRank and I guess that would be fine.

Is there anywhere you can read about their stance on this? Is it independently verified or something(I guess not)?