Real Solvability of the Equation @ 2 and the Topology of Isolated Umbilics
نویسنده
چکیده
The geometric form of a conjecture associated with the names of Loewner and Carath eodory states that near an isolated umbilic in a smooth surface in R 3 , the principal line elds must have index 1. Real solutions of the diierential equation @ 2 z ! = g , where the complex function g is given only up to multiplication by a positive function, are intimately related to umbil-ics. We determine necessary and suucient conditions of an integral nature for real solvability of this equation, which is really a system of two wave equations. We then construct germs of line elds of every index j 2 1 2 Z on S 2 that cannot be realised as the Gauss image of the principal line elds near an isolated umbilic of positive curvature on any smooth surface in R 3. These include the standard dipole line eld of index two and controlled distortions of it.
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تاریخ انتشار 2005