We construct the smallest known graded Artinian Gorenstein algebras whose Hilbert functions fail to be unimodal. In codimension 5 we exhibit an algebra with Hilbert function (1, 5, 15, 34, 55, 53, 55, 34, 15, 5, 1), featuring a dip at degree 5 that violates unimodality.
Let (A,m) be an excellent normal local domain of dimension d >= 2, and let I be an m-primary ideal. We define the reduced comparison map phi_n^r : Sym_A^n(I)/r Sym_A^n(I) -> I^n_bar/r I^n_bar for a nonzero conductor element r in m intersect c(I), and prove: (1) the exact index formula lambda(ker phi_n^r) - lambda(coker phi_n^r) = lambda(E_n) relating the comparison map to the equation defect; (2) the exact decomposition nu_r(n) = d_r(n) + kappa_r(n) - tau_r(n) of the reduced normalization defect, where tau_r(n) is identified as an explicit intersection defect; (3) the asymptotic R_1 criterion deg nu_r(n) <= d-2 iff R(I) is R_1; and (4) a fiber-corrected bridge theorem: if the fiber-cone equation ideal J_fib vanishes, then lambda(E_n) = O(n^{d-2}).