http://www.ams.org/journals/ 美国数学会的期刊网,不过印象中欧洲的数学会更强大一些.其中 Notices , Bulletin 都是免费的.能在这上面发表文章的听说是牛人. Journal of the American Mathematical Society , Mathematics of Computation , Proceedings of the ...
Compact的不同定义: Formally, a topological space is called compact if each of its open covers has a finite subcover . Otherwise it is called non-compact . A set S of real numbers is called compact if every sequence in S has a subsequence that converges to an element again co ...