Projective Linking and Boundaries of Positive Holomorphic Chains in   Projective Manifolds, Part II
  In Part I of this paper we introduced the notion of the projective linking number Link(M,Z) of a compact oriented real submanifold M of dimension 2p-1 in complex projective n-space P^n with an algebraic subvariety Z of codimension p in P^n - M. It is shown here that a basic conjecture concerning the projective hull of real curves in P^2 implies the following result:   M is the boundary of a positive holomorphic p-chain T of mass M(T) < K in P^n if and only if Link(M,Z) > -K p!deg(Z) for all algebraic subvarieties Z of codimension p in P^n - M.   An analogous result is implied in any projective manifold X.   The above theorem implies a duality between relative and absolute homology classes which are represented by positive holomorphic chains. 
F. Reese Harvey and H. Blaine Lawson Jr