On the Quantum Quarter Plane and the Real Quantum Plane
  Suppose q is a complex number of modulus one and different from 1,-1. Let O(R^2_q) be the *-algebra with two hermitean generators x and y satisfying the relation xy=qyx. Using operator representations of the *-algebra O(R^2_q) on Hilbert space and the Weyl calculus of pseudodifferential operators we construct *-algebras of ``functions'' on the quantum quarter plane R^{++}_q and on the real quantum plane R^2_q which are left module *-algebras for the Hopf *-algebra U_q(gl_2(R)). We define a family h_k, k\in Z^2, of covariant positive linear functionals on these *-algebras and study the actions of the *-algebras O(R^2_q) and U_q(gl_2(R)) on the associated Hilbert spaces. Quantum analogs of the partial Fourier transforms and the Fourier transform are found. A differential calculus on the ``function'' *-algebras is also developed and investigated.   A shorter version appeared in International Journal of Mathematics 13 (2002), 279-321. 
Konrad Schmuedgen