Geodesic
Degeneration and resonance phenomena in the wave propagation problems
Zapiski Nauchnykh Seminarov POMI, Mathematical problems in the theory of wave propagation. Part 11, Tome 104 (1981), pp. 217-227 
A. S. Starkov. Degeneration and resonance phenomena in the wave propagation problems. Zapiski Nauchnykh Seminarov POMI, Mathematical problems in the theory of wave propagation. Part 11, Tome 104 (1981), pp. 217-227. http://geodesic.mathdoc.fr/item/ZNSL_1981_104_a19/
@article{ZNSL_1981_104_a19,
     author = {A. S. Starkov},
     title = {Degeneration and resonance phenomena in the wave propagation problems},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {217--227},
     year = {1981},
     volume = {104},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1981_104_a19/}
}
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VL  - 104
UR  - http://geodesic.mathdoc.fr/item/ZNSL_1981_104_a19/
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%J Zapiski Nauchnykh Seminarov POMI
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%P 217-227
%V 104
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%G ru
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The paper deals with waves interaction near the point of intersection of dispersive curves or the point where one dispersive curve is close to other ones. A new class of special functions which describee the behavior of normal waves is obtained. It is shown that these functions describe a solution in the neighbourhoods of points of intersections of caustics or points where a distance between caustics is small.