An answer to Hermann's conjecture on Bleimann–Butzer–Hahn operators

We give a negative answer to the conjecture of Hermann On the operator of Bleimann, Butzer and Hahn, in: J. Szabados, K. Tandori (Eds.), Approximation Theory, Proc. Conf., Kecskemét/Hung., 1990, North-Holland Publishing Company, Amsterdam, 1991, Colloq. Math. Soc. János Bolyai 58 (1991) 355–360] on Bleimann–Butzer–Hahn operators L_n. Our main result states that for each locally bounded positive function h there exists a continuous positive function f defined on 0,∞) with L_nf→f(n→∞), pointwise on 0,∞), such that

Moreover we construct an explicit counterexample function to Hermann's conjecture.