A few expanding Lie algebras of the Lie algebra A1 and applications

Based on two foundational subalgebras of the Lie algebra A1, a few expanding higher-dimensional Lie algebras are presented to generate four integrable couplings of a soliton equation hierarchy. The Hamiltonian structure for one of them is obtained by using the quadratic-form identity. The classification of the Lie algebras is also given. Moreover, a decomposition of one higher-dimensional Lie algebra is demonstrated to produce a q-integrable expanding hierarchy for generalized q-form KdV hierarchy.