訂正日: 2006/08/29訂正理由: -訂正箇所: 引用文献情報訂正内容: Right : [1] T. Tannaka, Some remarks concerning p-adic number field, Jour. of Math. Soc. of Japan, 3 (1951), pp. 252-257. [2] O. Schreier, Über die Erweiterung von Gruppen I, Monatsh. für Math. u. Phys., 34 (1926), pp. 165-180. [3] R. C. Lyndon, The cohomology theory of group extensions, Duke Math. Journal, 15 (1948), pp. 271-292. [4] S. Takahashi, Cohomology groups of finite abelian groups, Tohoku Math. Journ., 4 (1952), pp. 294-302.