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Computing Rational Radical Sums in Uniform TC^0 Hunter, Paul Bouyer, Patricia Markey, Nicolas Ouaknine, Joël Worrell, James Sum of square roots Threshold circuits Complexity A fundamental problem in numerical computation and computational geometry is to determine the sign of arithmetic expressions in radicals. Here we consider the simpler problem of deciding whether $\sum_{i=1}^m C_i A_i^{X_i}$ is zero for given rational numbers $A_i$, $C_i$, $X_i$. It has been known for almost twenty years that this can be decided in polynomial time. In this paper we improve this result by showing membership in uniform TC0. This requires several significant departures from Blömer's polynomial-time algorithm as the latter crucially relies on primitives, such as gcd computation and binary search, that are not known to be in TC0. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Paul Hunter and Patricia Bouyer and Nicolas Markey and Joël Ouaknine and James Worrell 2010 Is Part Of LIPIcs, Volume 8, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2010) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.FSTTCS.2010.308 urn:nbn:de:0030-drops-28739 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2010.308 eng https://creativecommons.org/licenses/by-nc-nd/3.0/legalcode