Boundary Value ProblemsVolume 2006 (2006), Article ID 87483, 7 pagesdoi:10.1155/BVP/2006/87483

# Shobha Oruganti1 and R. Shivaji2

1Department of Mathematics, School of Science, The Behrend College, Penn State Erie, Erie 16563, PA, USA
2Department of Mathematics and Statistics, Mississippi State University, Mississippi State 39762, MS, USA

Received 22 September 2005; Accepted 10 November 2005

Copyright © 2006 Shobha Oruganti and R. Shivaji. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

We study positive C1(Ω¯) solutions to classes of boundary value problems of the form Δpu=g(x,u,c) in Ω,u=0 on Ω, where Δp denotes the p-Laplacian operator defined by Δpz:=div(|z|p2z); p>1, c>0 is a parameter, Ω is a bounded domain in RN; N2 with Ω of class C2 and connected (if N=1, we assume that Ω is a bounded open interval), and g(x,0,c)<0 for some xΩ (semipositone problems). In particular, we first study the case when g(x,u,c)=λf(u)c where λ>0 is a parameter and f is a C1([0,)) function such that f(0)=0, f(u)>0 for 0<u<r and f(u)0 for ur. We establish positive constants c0(Ω,r) and λ*(Ω,r,c) such that the above equation has a positive solution when cc0 and λλ. Next we study the case when g(x,u,c)=a(x)up1uγ1ch(x) (logistic equation with constant yield harvesting) where γ>p and a is a C1(Ω¯) function that is allowed to be negative near the boundary of Ω. Here h is a C1(Ω¯) function satisfying h(x)0 for xΩ, h(x)0, and maxxΩ¯h(x)=1. We establish a positive constant c1(Ω,a) such that the above equation has a positive solution when c<c1 Our proofs are based on subsuper solution techniques.