Steps to reproduce the Google bug:
- Go to Google and type: "ac motor" "servo motor" "electrical motor" (or any other query with multiple phrases), execute search.
- Click "Advanced Search" next to the search box.
Notice that the query has been translated into something different: (all the words: servo-motor electrical-motor, and exact phrase: ac motor). In essence, the first phrase is filled in as an "exact phrase", subsequent phrases appear as hyphonated terms in the "all the words" form.
- Execute click search. The results are different than from the original query, although the differences are minor, in this case the top three results are not affected, but other results are in different order and the second query contains a result (www.engnet.us/p/p.aspx/Ele/mot03) not in the original result set.
The bug appears to be the way the Advanced Search page interprets the original user query.