Oscillating Tchebycheff systems

AbstractAs is well known the Tchebycheff polynomial of degree n minimizes the sup norm over all monic polynomials with n simple zeros in [−1,+1). B. D. Bojanov [J. Approx. Theory, 26 (1979), 293–300] recently investigated the situation for polynomials with a full set of zeros of higher multiplicities. In this paper we generalize these results to extended complete Tchebycheff systems