No CrossRef data available.
Published online by Cambridge University Press: 12 July 2007
By a new approach and different techniques, the present paper will give an essential generalization of a main theorem of Hasson. We also show that there do exist functions that satisfy the condition in our theorem, which we suggest to replace Hasson's condition (H1) or (H2) (for k = 1), but do not satisfy Hasson's condition. This gives a negative answer to a question raised by Hasson.