论文标题
希尔伯特空间的封闭子空间的总和何时关闭？
When is the sum of closed subspaces of a Hilbert space closed?
论文作者
论文摘要
我们为希尔伯特空间的有限数量的封闭子空间提供了足够的条件，可以线性独立并将其封闭。在这种情况下，给出了对总和的正交投影的公式。我们还表明，这种情况是鲜明的（从某种意义上说）。
We provide a sufficient condition for a finite number of closed subspaces of a Hilbert space to be linearly independent and their sum to be closed. Under this condition a formula for the orthogonal projection onto the sum is given. We also show that this condition is sharp (in a certain sense).
