In another mishap, he asked Cortana to convert a temperature from Farenheit to Celsius, which worked, but when he asked Cortana to covert that temperature reading to the Kelvin temperature scale, Cortana twice repeated, "I converted to Celsius ..."
Belfiore called that mishap "the vagaries of a service that's live and up and down ... We tried to make her smart."
Cortana can also recognize through a user's closest connections, based on the frequency they are contacted and other usage patterns, Belfiore said. The list of closest personal connections can help Cortana decide whether to put through a late night call. The close personal contact list can be customized by the user, based on Cortana's suggestions.
Belfiore saved his riskiest demo for last, in which he used fingers on a smartphone's virtual keyboard to show how shape writing works. Only one mispelling occurred in the complex sentence he typed: "Being onstages at Build is simultaneously delightful and horrifying. Of course I love to hear from developers, but occasionally techies can be intimidating."
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