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May 3, 2016 at 12:06 history edited Neil Strickland CC BY-SA 3.0
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Apr 30, 2016 at 15:11 comment added Neil Strickland OK, I see your point. I might look at this again tomorrow.
Apr 30, 2016 at 14:37 comment added Tyrone The fibration resulting from applying the functor $Map_*(-,X)$ to a cofiber sequence only works in the pointed topological category: it needs all spaces to be based. Thus the fibre it produces is really the fibre over the basepoint component, in this case $Map_*^{(0,0)}(\mathbb{C}P^2,BU(2))$ containing the trivial map. There is no particular reason why the fibre over the non-basepoint component $Map_*^{(1,0)}(\mathbb{C}P^2,BU(2))$ should be of the same homotopy type. In fact they are not and $Map_*^{(1,0)}(\mathbb{C}P^2,BU(2))\not\simeq Map_*^{(0,0)}(\mathbb{C}P^2,BU(2))$ (calculate $\pi_4$).
Apr 30, 2016 at 14:35 comment added Tyrone The problem with this is that the map induced by $BS^3\rightarrow BU(2)$ takes the $l$ component of $Map_*(\mathbb{C}P^2,BS^3)$ into the $(0,l)$ component of $Map_*(\mathbb{C}P^2,BU(2))$, i.e. $Map_*^l(\mathbb{C}P^2,BS^3)\rightarrow Map_*^{(0,l)}(\mathbb{C}P^2,BU(2))$. The coaction induced by the pinch map $\mathbb{C}P^2\rightarrow S^4$ then may be used to get homotopy equivalences $Map_*^{(0,l)}(\mathbb{C}P^2,BU(2))\simeq Map_*^{(0,0)}(\mathbb{C}P^2,BU(2))$ And these later spaces certainly sit in the fiber sequence you defined but consider the $(1,l)$ component in which I am interested.
Apr 29, 2016 at 17:57 history answered Neil Strickland CC BY-SA 3.0