The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-16235-5_2We study the weak duality S(x, N(x)) = N(T (x, N(x))) where S is a continuous t-conorm, T is a continuous t-norm and N is a strong negation. We characterize completely the strict cases and show that in all other cases there is no direct relation between generators of T and S or between their possible Archimedean components in ordinal sums.Peer ReviewedPostprint (author’s final draft