  Adopting the graph-theoretic approach to the correlation experiments, we
analyze the origin of monogamy and prove that it can be recognized as a
consequence of the exclusivity principle(EP). We provide an operational
criterion for monogamy: if the fractional packing number of the graph
corresponding to the union of event sets of several physical experiments does
not exceed the sum of independence numbers of each individual experiment graph,
then these experiments are monogamous. As applications of this observation,
several examples are provided, including the monogamy for experiments of
Clauser-Horne-Shimony-Holt (CHSH) type, Klyachko-Can-Binicio\u{g}lu-Shumovsky
(KCBS) type, and for the first time, we give some monogamy relations of
Svetlichny's genuine nonlocality. We also give the necessary and sufficient
conditions for several experiments to be monogamous: several experiments are
monogamous if and only if the Lov\'asz number of the union exclusive graph is
less than or equal to the sum of independence numbers of each exclusive graph.
