2005 年 59 巻 1 号 p. 101-116
Let Pn be the real n-dimensional projective space. We determine the group structure of the self-homotopy set of the double suspension of Pn where n is 3, 4, 5 and 6 using the ideas and methods of the second author (The suspension order of the real even dimensional projective space, J. Math. Kyoto Univ. 43(4) (2003), 755-769).