On 'valid sequences' considered by Wigner. - W. H. Olson; V. R. R. Uppuluri (Discret. Math., 1973)

On stochastic approximation algorithms for classes of PAC learning problems. - Nageswara S. V. Rao; V. R. R. Uppuluri; E. M. Oblow (IEEE Trans. Syst. Man Cybern. Part B, 1997)