Reduction theorem: f(n) = h(⌈(n−1)/2⌉) for all n ≥ 1, where h(m) is the minimum over sets U of m distinct nonzero reals with no two elements summing to 0 of the largest dissociated subset of U; h is nondecreasing. Proof: sign flips preserve dissociativity; a dissociated set contains no 0 and at most one element per sign-class {x,−x}, and class representatives can be chosen inside A, so md(A) = md(R) for the representative set R, |R| ≥ ⌈(n−1)/2⌉; conversely {0} ∪ {±u_i} realizes equality.