Упражнение: докажите, что любую поверхность (компактную связную без края) можно получить из сферы последовательностью раздутий и сдутий.
«Топологическая гипотеза Нэша», доказанная Г.Михалкиным: аналогичное утверждение верно в любой размерности — любое вещественное многообразие (гладкое компактное связное без края) можно превратить в любое другое последовательностью раздутий и сдутий вдоль подмногообразий.
Упражнение: докажите, что любую поверхность (компактную связную без края) можно получить из сферы последовательностью раздутий и сдутий.
«Топологическая гипотеза Нэша», доказанная Г.Михалкиным: аналогичное утверждение верно в любой размерности — любое вещественное многообразие (гладкое компактное связное без края) можно превратить в любое другое последовательностью раздутий и сдутий вдоль подмногообразий.
// via ppetya
BY Непрерывное математическое образование
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WhatsApp, a rival messaging platform, introduced some measures to counter disinformation when Covid-19 was first sweeping the world. And while money initially moved into stocks in the morning, capital moved out of safe-haven assets. The price of the 10-year Treasury note fell Friday, sending its yield up to 2% from a March closing low of 1.73%. Right now the digital security needs of Russians and Ukrainians are very different, and they lead to very different caveats about how to mitigate the risks associated with using Telegram. For Ukrainians in Ukraine, whose physical safety is at risk because they are in a war zone, digital security is probably not their highest priority. They may value access to news and communication with their loved ones over making sure that all of their communications are encrypted in such a manner that they are indecipherable to Telegram, its employees, or governments with court orders. The S&P 500 fell 1.3% to 4,204.36, and the Dow Jones Industrial Average was down 0.7% to 32,943.33. The Dow posted a fifth straight weekly loss — its longest losing streak since 2019. The Nasdaq Composite tumbled 2.2% to 12,843.81. Though all three indexes opened in the green, stocks took a turn after a new report showed U.S. consumer sentiment deteriorated more than expected in early March as consumers' inflation expectations soared to the highest since 1981. "Like the bombing of the maternity ward in Mariupol," he said, "Even before it hits the news, you see the videos on the Telegram channels."
from pl
