Homology of connected sum

From Topospaces

This article describes the effect of the connected sum operation on the following invariant: homology groups

Statement

Suppose and are the connected manifolds of dimension whose connected sum is being taken. Assume both We have:

Case for Additional condition on What is known about and ? Formula for in terms of homology groups of and
0 none both isomorphic to (because both are connected, so is their connected sum).
Greater than 0, less than none both are finitely generated abelian groups
Both manifolds are compact, at least one of them is orientable both are finitely generated abelian groups, at least one is free abelian
other cases ? ?
Both are compact and orientable both are
other cases ? ?
Greater than none both are zero groups 0

Euler characteristic

The Euler characteristics are related by the following formula when both and are compact connected manifolds: