# Research Group of Prof. Dr. Ira Neitzel

## 2017

1. Tangent and normal cones for low-rank matrices. S. Hosseini, D. R. Luke, and A. Uschmajew. INS Preprint No. 1715, oct 2017.
2. A collection of nonsmooth Riemannian optimization problems. P.-A. Absil and S. Hosseini. INS Preprint No. 1713, sep 2017.
3. Second order optimality conditions for optimal control of quasilinear parabolic pdes. L. Bonifacius and I. Neitzel. Mathematical Control and Related Fields, 2017. Accepted. Preprint version available as INS Preprint No. 1705.

## 2016

1. Line search algorithms for locally Lipschitz functions on Riemannian manifolds. S. Hosseini, W. Huang, and R. Yousefpour. INS Preprint No. 1626. Revised version, August 2017, nov 2016.
2. A gradient sampling method on algebraic varieties and application to nonsmooth low-rank optimization. S. Hosseini and A. Uschmajew. INS Preprint No. 1624. Extended and revised version, March 2017, oct 2016.
3. A-posteriori error estimation of discrete pod models for pde-constrained optimal control. M. Gubisch, I. Neitzel, and S. Volkwein. In Model reduction and approximation: theory and algorithms, volume of Computational Science and Engineering, pages. SIAM.
4. A priori $l^2$-discretization error estimates for the state in elliptic optimization problems with pointwise inequality state constraints. I. Neitzel and W. Wollner. Numer. Math., 2017. also available as INS Preprint No. 1606.
5. A priori error estimates for state constrained semilinear parabolic optimal control problems. F. Ludovici, I. Neitzel, and W. Wollner. 2016. in revision, also available as INS Preprint No. 1605.

## 2015

1. Convergence of nonsmooth descent methods via Kurdyka–Łojasiewicz inequality on Riemannian manifolds. S. Hosseini. INS Preprint No. 1523. Revised version, July 2017, nov 2015.