Universal coefficient theorem

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Let RR be a commutative ring with 1. Define an RR-homology sphere to be a Hausdorff topological space XX such that Hi(X;R)≅Hi(Sn;R)H_{i}(X;R) \cong H_{i}(S^{n}; R) for some sphere SnS^{n}.

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(a)

Let WW be a compact connected (n+1)(n+1)-manifold and let X=∂WX = \partial W. Suppose that Hi(W,Z2)=0H_{i}(W, \mathbb {Z}_{2}) = 0 for all i>0i > 0. Prove that XX is a Z2\mathbb {Z}_{2}-homology sphere.

(b)

Give an example of RR and an RR-homology sphere which is a non-orientable connected compact manifold. Justify your answer by quoting appropriate theorems. You may quote standard computations without proof.

References

[CJP+11] Chen J., Jiang G., Pan Y., Qin T., Tong Y., Wu Q., Xu S., Li T. Problems and Solutions in Mathematics. 2nd ed., World Scientific, 2011.