The Prime ideal Stratification and The Automorphism Group of U⁺_(r,s)(B₂)

Let ${\mathfrak g}$ be a finite dimensional complex simple Lie algebra, and let $r,s\in \mathbb{C}^{\ast}$ be transcendental over $\mathbb{Q}$ such that $r^{m}s^{n}=1$ implies $m=n=0$. We will obtain some basic properties of the two-parameter quantized enveloping algebra $U_{r,s}^{+}(\mathfrak g)$. In particular, we will verify that the algebra $U_{r,s}^{+}(\mathfrak g)$ satisfies many nice properties such as having normal separation, catenarity and Dixmier-Moeglin equivalence. We shall study a concrete example, the algebra $U_{r,s}^{+}(B_{2})$ in detail. We will first determine the normal elements, prime ideals and primitive ideals for the algebra $U_{r,s}^{+}(B_{2})$, and study their stratifications. Then we will prove that the algebra automorphism group of the algebra $U_{r,s}^{+}(B_{2})$ is isomorphic to $(\mathbb{C}^{\ast})^{2}$.