The null identities for boundary operators in the (2, 2p + 1) minimal gravity

By using the matrix model representation, we show that correlation numbers of boundary-changing operators (BCOs) in |$(2,2p+1)$| minimal Liouville gravity satisfy some identities, which we call the null identities. These identities enable us to express the correlation numbers of BCOs in terms of those of boundary-preserving operators. We also discuss a physical implication of the null identities as the manifestation of the boundary interaction.