The department argued in a court filing that OpenAI legally used articles by The New York Times to develop A.I., adding that national security depended on American tech dominance.

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Meta, the social media giant, agreed to change the way children interact with its apps. That could be trouble if its competitors don’t abide by the same rules.

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Denise Dresser, who was previously the C.E.O. of Slack, is the latest in a string of executives to leave the artificial intelligence start-up.

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