  We consider a measure of cooperativity based on the minimal absolute
interaction required to generate an observed titration behavior. We describe
the corresponding algebraic optimization problem and show how it can be solved
using the nonlinear algebra tool \texttt{SCIP}. Moreover, we compute the
minimal absolute interactions for various binding polynomials that describe the
oxygen binding of various hemoglobins under different conditions. While
calculated minimal absolute interactions are consistent with the expected
outcome of the chemical modifications, it ranks the cooperativity of the
molecules differently than the maximal Hill slope.
