Sl. Samelson et Wp. Dayawansa, ON THE EXISTENCE OF GLOBAL TCHEBYCHEV NETS, Transactions of the American Mathematical Society, 347(2), 1995, pp. 651-660
Let S be a complete, open simply connected surface. Suppose that the i
ntegral of the Gauss curvature over arbitrary measurable sets is less
than pi/2 in magnitude. We show that the surface admits a global Tcheb
ychev net.