  A_k = {1, a_2, ... a_k} is an h-basis for X if every positive integer not
exceeding X can be expressed as the sum of no more than h values a_i; X(h) is
called the h-range of the basis. h_0 is the smallest value of h for which X(h)
is greater than or equal to a_k, and h_1 is the smallest value for which X(h+1)
= X(h) + a_k for all h greater than or equal to h_1. h_2 identifies a further
"stabilisation" in the h-range - a definition is included in the body of the
paper. It is known that h_1 and h_2 do not exceed h_0 for h-bases A_3, but
published proofs are complicated (see Ch. VIII of [4], where references [3] and
[5] are given). This paper introduces the concept of a "stride generator" A =
{1, a_2, a_3} which, while sharing some of the properties of a basis A_3, is
simpler to treat mathematically. We establish a relationship between stride
generators and h-bases, and show that the result follows immediately if the
stride generator underlying a basis has a particular property - here called
"canonicality". The proof is lengthy (with a number of special cases to
consider), but the underlying principles remain simple.
