“…For e ∈ G (1) [14]). Let X ≡ {u, v} and consider the maps σ i : X → X , i = 1, 2, with σ i (u) = v and σ i (v) = v. Set σ ≡ (σ 1 , σ 2 ) and let O (X ,σ) be the Cuntz-Pimsner algebra associated with the multivariable system (X , σ), which by [13] is the C * -envelope of the associate tensor algebra.…”