@article {2004,
title = {Fredholm modules for quantum euclidean spheres},
journal = {J. Geom. Phys. 49 (2004) 272-293},
number = {SISSA;66/2002/FM},
year = {2004},
publisher = {SISSA Library},
abstract = {The quantum Euclidean spheres, $S_q^{N-1}$, are (noncommutative) homogeneous spaces of quantum orthogonal groups, $\\\\SO_q(N)$. The *-algebra $A(S^{N-1}_q)$ of polynomial functions on each of these is given by generators and relations which can be expressed in terms of a self-adjoint, unipotent matrix. We explicitly construct complete sets of generators for the K-theory (by nontrivial self-adjoint idempotents and unitaries) and the K-homology (by nontrivial Fredholm modules) of the spheres $S_q^{N-1}$. We also construct the corresponding Chern characters in cyclic homology and cohomology and compute the pairing of K-theory with K-homology. On odd spheres (i. e., for N even) we exhibit unbounded Fredholm modules by means of a natural unbounded operator D which, while failing to have compact resolvent, has bounded commutators with all elements in the algebra $A(S^{N-1}_q)$.},
doi = {10.1016/S0393-0440(03)00092-5},
url = {http://hdl.handle.net/1963/1636},
author = {Eli Hawkins and Giovanni Landi}
}