Uniqueness of contractible coboundary (Ex)

Let $\Sigma$$<wikitex>; Let $\Sigma$ be a homology 3-spheres. If $\Sigma$ is the boundary of compact, contractible 4-manifolds $\Omega_1$ and $\Omega_2$ show there is a homeomorphism $\Omega_1 \to \Omega_2$ which is the identity on the boundary. (Hint: You may have to use the h-cobordism theorem for manifolds with boundary._ </wikitex> [[Category:Exercises]] [[Category:Exercises without solution]]\Sigma$ be a homology 3-spheres. If $\Sigma$$\Sigma$ is the boundary of compact, contractible 4-manifolds $\Omega_1$$\Omega_1$ and $\Omega_2$$\Omega_2$ show there is a homeomorphism $\Omega_1 \to \Omega_2$$\Omega_1 \to \Omega_2$ which is the identity on the boundary. (Hint: You may have to use the h-cobordism theorem for manifolds with boundary.)