Let C_T be the subgroup of the smooth knot concordance group generated by
topologically slice knots and let C_D be the subgroup generated by knots with
trivial Alexander polynomial. We prove the quotient C_T/C_D is infinitely
generated, and uncover similar structure in the 3-dimensional rational spin
bordism group. Our methods also lead to the construction of links that are
topologically, but not smoothly, concordant to boundary links.
We show that the subgroup of the knot concordance group generated by links of
isolated complex singularities intersects the subgroup of algebraically slice
knots in an infinite rank subgroup.
We show that the subgroup of the knot concordance group generated by links of
isolated complex singularities intersects the subgroup of algebraically slice
knots in an infinite rank subgroup.