  We consider an adaptive algorithm for finite element methods for the
isogeometric analysis (IGAFEM) of elliptic (possibly non-symmetric)
second-order partial differential equations. We employ analysis-suitable
T-splines of arbitrary odd degree on T-meshes generated by the refinement
strategy of [Morgenstern, Peterseim, Comput. Aided Geom. Design 34 (2015)] in
2D and [Morgenstern, SIAM J. Numer. Anal. 54 (2016)] in 3D. Adaptivity is
driven by some weighted residual a posteriori error estimator. We prove linear
convergence of the error estimator (which is equivalent to the sum of energy
error plus data oscillations) with optimal algebraic rates with respect to the
number of elements of the underlying mesh.
