A simplified method of recognizing zero among elementary constants Daniel Richardson, Department of Mathematics, University of Bath, Bath BA2, England.
[email protected]. maths Abstract unique non singular solution in N, (r). The question of how such a proof can be given will be discussed later. In ISSAC ’94, a method was given for deciding whether or A basic problem about the elementary numbers is how not an elementary constant, given as a polynomial image of to decide, given a description, as above, of an elementary a solution of a system of exponential polynomial equations, number, whether or not the number is zero. This is called represents the famous object zero. the element ary constant problem [see Richardson, 1992]. In this article the technique is considerably simplified The solution given below is an improved version of the and speeded up. The main improvement has been to in- solution given in the 1994 ISSAC [Richardson and Fitch]. tegrate the numerical and symbolic computations in such a Both solutions rely upon not stumbling over a counterex- way that unnecessary branches of the symbolic computation ample to the following conjecture. are avoided. Schanuel’s Conjecture If ZI, ..., Zk are ~ comPlex num- bers which are linearly independent over the rationals, then 1 The elementary numbers the transcendence rank of An exponential system is a system of equations (S = O,E = zk,l,l, ezk}ezk} O), where S is a finite set of polynomials in QIx1, Y1, ..., xn> Yn], {.2,,..., and E is a subset of {ul —ezl, . ,Y~ —e“ } is at least k We will write (S., E~ ) for an exponential system with r polynomials and k exponential terms.