摘要：0.13 Show that every graph with two or more nodes contains two nodes that have equal degrees. Proof. Assume no self-edges (otherwise exists counterexa 阅读全文

摘要：求极限 \[\lim_{n\to\infty}\left(\frac{1\cdot3\cdot5\cdots(2n-1)}{2\cdot4\cdot6\cdots(2n)}\right)^\frac1n。 \]解：令 \[f(n)=\left(\frac{1\cdot3\cdot5\cdots(2n 阅读全文