Let I be the toric ideal defined by a 2 x n matrix of integers, A = ((1 1 ...
1)(a_1 a_2 ... a_n)) with a_1<a_2<...<a_n. We give a combinatorial proof that I
is generated by elements of degree at most the sum of the two largest
differences a_i - a_(i-1). The novelty is in the method of proof: the result
has already been shown by L'vovsky using cohomological arguments.Comment: 8 pages. To appear in Collectanea Mathematic