Array ( [0] => Array ( [title] => L6A [link] => https://www.youtube.com/embed/Pe2ZB6-Vz0Q ) [1] => Array ( [title] => L6B [link] => https://www.youtube.com/embed/hEsutA80Va4 ) ) 國立清華大學開放式課程OpenCourseWare(NTHU, OCW) - 第6R講 Chapter 2 : Compactness property