## Small Terms
The lowest-order expansion keeps only , since is dominated by (when is small) and is dominated by (when is small). Note that although is of total order 5, compared with order 4 for , it is not known to be smaller than the second term because we don't know if x, y, z are small or large relative to each other. How can I find the lowest-order expansion? Daniel Lichtblau (danl@wolfram.com) answers: You want to keep only those terms whose power-products are not divisible by those of other terms. These terms can be found using a Groebner basis of the set of monomials. After recovering the coefficients, the lowest-order expansion is |