On homotopy and homology cobordism groups

We will discuss the celebrated result of Kervaire and Milnor in the 1960s: the n-dimensional homotopy cobordism group is finite unless n=3. Further, we will investigate the interesting theorem of Gonzalez-Acuna in the 1970s: the n-dimensional homotopy and homology cobordism groups are isomorphic unless n=3.