The parametric symmetry and numbers of the entangled class of 2 x M x N system

We present in the work two intriguing results in the entanglement classification of a pure and true tripartite entangled state of 2 x M x N under stochastic local operation and classical communication: (i) the internal symmetric properties of the nonlocal parameters in the continuous entangled class; (ii) the analytic expression for the total numbers of the true and pure entangled class 2 x M x N states. These properties help better understand the nature of the 2 x M x N entangled system.