Four manifold without point homotopy equivalent to wedge of two-spheres? Let $X$ be a closed, simply-connected four-manifold. Let $X'$ be obtained from $X$ by removing a point. Is $X'$ homotopy equivalent to a wedge of $S^2$s?
 A: Here is a hopefully better answer which is copied from page 104 of Milnor-Husemoller's book on symmetric bilinear forms.
$X^\prime$ is also simply connected (Seifert-van Kampen reversed) and thus has torsion-free $H_2={\mathbb Z}^r$ (otherwise the torsion would contribute nontrivially to $H^3$ via the universal coefficient theorem) and $\pi_2=H_2$ (Hurewicz).
So there is a map $S^2\vee\ldots\vee S^2\to X^\prime$ that induces a homology isomorphism, hence (by Hurewicz) a weak homotopy equivalence, hence (because $X^\prime$ is an ANR) a homotopy equivalence.
A: A closed, simply connected manifold has a Morse function with one critical point of index 0 and no critical point of index 1. Thus it is homotopy equivalent to a CW-complex with one 0-cell, no 1-cell, some 2-cells, no 3-cell, one 4-cell. Removing a point is homotopy equivalent to removing the 4-cell, you get a CW-complex with one point and several 2-cells attached to it, that is, a wedge of 2-spheres.
EDIT: This actually seems to be known only in dimensions $\ge5$, which is the case handled in Milnor's book on the h-cobordism theorem. The 4-dimensional case seems to be open, according to Existence of Morse functions on simply connected manifolds
