“三鸽飞进两窝,必有一窝至少两鸽.”“有n+1件物品装入n个抽屉,一定有某个抽屉中至少有2件物品.”以上是很简单的常识(不难用反证法证明),却有大量出乎意料的应用,德国数学家狄里克雷(Dirichlet,1805-1859)明白、成功地运用上述原理证明重要数学定理,因此“鸽窝原理”或“抽屉 “Three pigeons fly into two nests and there must be at least two pigeons.” “There are n+1 items in n drawers. There must be at least 2 items in a drawer.” The above is a very simple common sense (no Difficult to prove by contradiction), but there is a large number of unexpected applications, the German mathematician Dirichlet (Dirichlet, 1805-1859) understands and successfully uses the above principles to prove important mathematical theorems, so the “pigeon principle” or "drawer