Acta mathematica scientia,Series B ›› 1994, Vol. 14 ›› Issue (S1): 40-45.

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EXISTENCE OF POSITIVE SOLUTION TO-Δu=f(x,u) WHEN f CHANGES SIGNS

Jiang Ming   

  1. Dept. Appl. Math, Beijing Institute of Technology, Beijing 100081, China
  • Received:1992-03-06 Online:1994-12-31 Published:1994-12-31
  • Supported by:
    Research supported by a Youth Grant from National Natural Science Foundation of China.

Abstract: The existence of positive solutions to the semlinear elliptic boundary value problem
-Δ=f(x,u) in Ω and u=0 on ∂Ω is studied in this paper. The result obtained differs from the other known results in that the positivity of the solution does not follow from the positivity of f.Our result roughly says that if Ω is not too wide in some one direction, there is always a positive solution even if f changes signs, which is proved using the so-calles sub-super solution approach.

Key words: Positive solution, Semliinear elliptic boundary valed problem

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