Neither Apple nor IBM could be reached for comment Tuesday, but there are a couple of important differences between Siri and Google that may have IBM worried: For one, Siri can be used to write e-mails or text messages.

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In effect, it gauges how busy the user is and the urgency of the new data, whether in the form of e-mails, telephone calls or text messages.

ECONOMIST: Computing

Then they wouldn't have to deal with the ambiguity of e-mails or the unclear signals of text messages.

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