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In its blog post, Google doesn't mention censorship, referring to the issue as a purely technical problem. It's obvious, however, that some of the terms are blocked due to political reasons. One example is "Jiang" -- a common surname in China, but also the name of former President Jiang Zemin. The Chinese authorities started censoring searches for the term after erroneous rumors of Jiang's death started spread in 2011.
Google's relationship with the Chinese authorities in the past couple of years has been uneasy, with the internet giant threatening to pull its services from China altogether at one point.