Problem 6 gives a precise meaning to the word "natural", formulated only after the term had long been in use. Once the meaning is made precise, we can prove that there is no natural isomorphism from V to V^*.
62 名前：１３２人目の素数さん 投稿日：2017/05/06(土) 08:46:30.01 ID:9LejwzyZ An airplane is flying near a radar tower. At the instant it is exactly 3 miles due west of the tower, it is 4 miles high and flying with a ground speed of 450 mph and climbing at a rate of 5 mph. If at that instant it is flying
(a) due east, (b) northeast,
at what rate is it approaching the radar tower at that instant?
285 名前：デフォルトの名無しさん 投稿日：2017/05/07(日) 15:18:15.45 ID:9xbdAkMv Hands-On Machine Learning with Scikit-Learn and TensorFlow: Concepts, Tools, and Techniques to Build Intelligent Systems by Aurelien Geron https://www.amazon.com/dp/1491962291/