Non-well-ordered lower and upper solutions for semilinear systems of PDEs

Author(s):  
Alessandro Fonda ◽  
Giuliano Klun ◽  
Andrea Sfecci

We prove existence results for systems of boundary value problems involving elliptic second-order differential operators. The assumptions involve lower and upper solutions, which may be either well-ordered, or not at all. The results are stated in an abstract framework, and can be translated also for systems of parabolic type.

2010 ◽  
Vol 2010 ◽  
pp. 1-15
Author(s):  
Piao-Piao Shi ◽  
Wen-Xia Wang

We investigate the infinite boundary value problems for second-order impulsive differential equations with supremum by establishing a new comparison result and using the lower and upper solution method, and obtain the existence results for their maximal and minimal solutions.


Author(s):  
Donal O'Regan

Existence results are established for second-order boundary value problems for ordinary differential equations on non-compact intervals.


Author(s):  
Ravi P. Agarwal ◽  
Donal O'Regan

AbstractExistence results are presented for second order discrete boundary value problems in abstract spaces. Our analysis uses only Sadovskii's fixed point theorem.


2010 ◽  
Vol 79 (3) ◽  
pp. 281-291
Author(s):  
P. S. Kelevedjiev ◽  
D. O’Regan ◽  
N. Popivanov ◽  
R. P. Agarwal

2004 ◽  
Vol 2004 (7) ◽  
pp. 577-590 ◽  
Author(s):  
Irena Rachůnková ◽  
Milan Tvrdý

We deal with the nonlinear impulsive periodic boundary value problemu″=f(t,u,u′),u(ti+)=Ji(u(ti)),u′(ti+)=Mi(u′(ti)),i=1,2,…,m,u(0)=u(T),u′(0)=u′(T). We establish the existence results which rely on the presence of a well-ordered pair(σ1,σ2)of lower/upper functions(σ1≤σ2 on [0,T])associated with the problem. In contrast to previous papers investigating such problems, the monotonicity of the impulse functionsJi,Miis not required here.


2003 ◽  
Vol 44 (4) ◽  
pp. 591-594 ◽  
Author(s):  
Patrick Habets ◽  
Rodrigo L. Pouso

AbstractStandard results for boundary value problems involving second-order ordinary differential equations ensure that the existence of a well-ordered pair of lower and upper solutions together with a Nagumo condition imply existence of a solution. In this note we introduce some examples which show that existence is not guaranteed if no Nagumo condition is satisfied.


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