Department of Mathematical Sciences, University of Arkansas, Fayetteville, Arkansas 72701 ; Department of Mathematics, Kansas State University, Manhattan, Kansas 66506
Abstract:
Extending a result of Khavinson and Swiatek (2003) we show that the rational harmonic function , where is a rational function of degree , has no more than complex zeros. Applications to gravitational lensing are discussed. In particular, this result settles a conjecture by Rhie concerning the maximum number of lensed images due to an -point gravitational lens.