A partially ordered Abelian group M is algebraically (existen-tially) closed in a class C ∈ M of such structures just in case any finite system of weak inequalities (and negations of weak inequalities), defined over , is solvable in M if solvable in some N ∈ M in C. After characterizing existentially closed dimension groups this paper derives amalgamation properties for dimension groups. dimension groups with order unit, and simple dimension groups. By determining the quantifier-free types that may be isolated by existential formulas the paper produces many pairwise nonembeddable countable finitely generic dnuension groups. The paper also finds several elementary properties distinguishing finitely generic dimension groups among existentially closed dimension groups. The paper finally embeds nontrivial dimension groups functorially into existentially closed dimension groups.
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