Before revision:  A swap portfolio is a portfolio in which each one of a pair of assets is held at a weight proportional to the market value of the other . A reverse-weighted index portfolio is a portfolio in which the weights of the market portfolio are swapped pairwise by rank.
After revision:  A swap portfolio is a portfolio in which the assets are held at weights proportional to a permutation of their market values, and such a portfolio is functionally generated only for markets with two assets (except for the identity permutation) . A reverse-weighted index portfolio is a portfolio in which the weights of the market portfolio are swapped pairwise by rank.