In mathematics, a smooth compact manifold M is called almost flat if for any there is a Riemannian metric on M such that and is -flat, i.e. for the sectional curvature of we have . Given n, there is a positive number such that if an n-dimensional manifold admits an -flat metric with diameter then it is almost flat. On the other hand, one can fix the bound of sectional curvature and get the diameter going to zero, so the almost-flat manifold is a special case of a collapsing manifold, which is collapsing along all directions.
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| - Almost flat manifold (en)
- Почти плоское многообразие (ru)
- Nästan platt mångfald (sv)
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| - Почти плоское многообразие — гладкое компактное многообразие М такое, что для любого на М существует риманова метрика ,такая, что и является -плоской,то есть её секционные кривизны в каждой точке удовлетворяют неравенству (ru)
- Inom matematiken säges en kompakt mångfald M vara nästan platt om för varje finns det en på M så att och är -platt, d.v.s. vi har olikheten för av . (sv)
- In mathematics, a smooth compact manifold M is called almost flat if for any there is a Riemannian metric on M such that and is -flat, i.e. for the sectional curvature of we have . Given n, there is a positive number such that if an n-dimensional manifold admits an -flat metric with diameter then it is almost flat. On the other hand, one can fix the bound of sectional curvature and get the diameter going to zero, so the almost-flat manifold is a special case of a collapsing manifold, which is collapsing along all directions. (en)
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| - In mathematics, a smooth compact manifold M is called almost flat if for any there is a Riemannian metric on M such that and is -flat, i.e. for the sectional curvature of we have . Given n, there is a positive number such that if an n-dimensional manifold admits an -flat metric with diameter then it is almost flat. On the other hand, one can fix the bound of sectional curvature and get the diameter going to zero, so the almost-flat manifold is a special case of a collapsing manifold, which is collapsing along all directions. According to the Gromov–Ruh theorem, M is almost flat if and only if it is infranil. In particular, it is a finite factor of a nilmanifold, which is the total space of a principal torus bundle over a principal torus bundle over a torus. (en)
- Почти плоское многообразие — гладкое компактное многообразие М такое, что для любого на М существует риманова метрика ,такая, что и является -плоской,то есть её секционные кривизны в каждой точке удовлетворяют неравенству (ru)
- Inom matematiken säges en kompakt mångfald M vara nästan platt om för varje finns det en på M så att och är -platt, d.v.s. vi har olikheten för av . (sv)
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