%0 Journal Article %T Forgetable map and phantom maps %A Pan Jianzhong %A Woo Moo Ha %J Mathematics %D 1999 %I arXiv %X In this note, we attack a question posed ten years ago by Tsukiyama about the injectivity of the so- called Forgetable map. We show that we can insert the Forgetable map in an exact sequence and that the problem can be reduced to the computation of the sequence which turns out unexpectedly to be related to the phantom map problem and the famous Halperin conjecture in rational homotopy theory. %U http://arxiv.org/abs/math/9907122v1