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On Some Exponential Equations of S. S. Pillai

Published online by Cambridge University Press:  20 November 2018

Michael A. Bennett*
Affiliation:
Department of Mathematics, University of Illinois, Urbana, IL 61801, USA. email: [email protected]
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Abstract

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In this paper, we establish a number of theorems on the classic Diophantine equation of S. S. Pillai, ${{a}^{x}}-{{b}^{y}}=c$ , where $a,\,b$ and $c$ are given nonzero integers with $a,\,b\,\ge \,2$. In particular, we obtain the sharp result that there are at most two solutions in positive integers $x$ and $y$ and deduce a variety of explicit conditions under which there exists at most a single such solution. These improve or generalize prior work of Le, Leveque, Pillai, Scott and Terai. The main tools used include lower bounds for linear forms in the logarithms of (two) algebraic numbers and various elementary arguments.

Keywords

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2001

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