A characterization of Ext(G,Z) assuming V=L

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In this paper we complete the characterization of Ext(G,Z) under Godel's axiom of constructibility for any torsion-free abelian group G. In particular, we prove in (V=L) that, for a singular cardinal nu of uncountable cofinality which is less than the first weakly compact cardinal and for every sequence of cardinals (nuₚ: p in P) satisfying nuₚ <= 2nu, there is a torsion-free abelian group G of size nu such that nuₚ equals the p-rank of Ext(G,Z) for every prime p and 2nu is the torsion-free rank of Ext(G,Z).