---- Google's Quality Problem - I'm bookmarking lots more these days
tedster - 7:28 pm on Oct 23, 2010 (gmt 0)
Bing/Yahoo (Bing first) is still making all effort to show the old web... the one based on word search, not "personalized" or "we know what you are thinking"
I wish I could find the exact quote that brings to mind. Sometime over the summer Microsoft acknowledged that they have "personalization envy" regarding Google. They want to do it, but they can't right now. So Bing may eventually show the same kinds of strangeness as they get up to speed.
Google will often return an exact phrase that it say isn't there when you make the search more general... either by unquoting it, as here, or by adding an extra word.
Good observation - and it does seem to point to phrase based indexing.
It's possible that the 4th word makes the phrase fall outside statistical relevance - those word strings that get tagged as a semantically significant phrase. This would mean that those URLs aren't as easily retrieved for the longer query.