Where αk is dual variable and yk is the label of the interaction pair (ik, jk) Equation 6 demonstrates that for a given site-ligand pair (s∗, l∗), it only relates with inner product of the support site-ligand pairs (αk ≠ 0). Therefore, we should only care 0 about the inner product of support site-ligand pairs and the site-ligand pair to predict.