Decay of the Kolmogorov N-width for wave problems. - Constantin Greif; Karsten Urban (Appl. Math. Lett., 2019)

Linear/Ridge expansions: enhancing linear approximations by ridge functions. - Constantin Greif; Philipp Junk; Karsten Urban (Adv. Comput. Math., 2022)

The Kolmogorov N-width for linear transport: exact representation and the influence of the data. - Florian Arbes; Constantin Greif; Karsten Urban (Adv. Comput. Math., 2025)