“…Mathematically, this is done by requiring the so-called bootstrap matrix to be always positive semidefinite, with its matrix elements obtained via some recursive relations (see Section II A for details). Their bootstrap method is soon applied to other quantum mechanical problems, such as harmonic oscillator, hydrogen, double-well potential, and Bloch bands [29][30][31][32][33][34][35]. Besides intelligential novelty, it is possible that these studies may eventually lead to an alternative formulation of quantum mechanics that will be important in the future.…”