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    • CommentRowNumber1.
    • CommentAuthorMurat_Aygen
    • CommentTimeFeb 18th 2018
    • (edited Feb 19th 2018)

    Theorem:

    Let KK be a complex with rr combinatorial components. Then H 0(K)H_{0}(K) is isomorphic to the direct sum of (not rr but) 2r2r copies of the group ZZ of integers.

    Proof for one component:

    As 0-cycles are synonymous with 0-chains, they have α 0\alpha_{0} many dimensions-of-freedom for sure. How many the 0-boundaries of our component have? Since the incidence matrix is a α 0\alpha_{0} by α 1\alpha_{1} matrix (see my previous posting with ‘homology’ tag), they have at least α 1α 0\alpha_{1} - \alpha_{0} many for sure. And 1 more for the rank deficiency! The proof follows from this arithmetic.