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Existence of Solutions for Fourth-Order Four-Point Boundary Value Problem on Time Scales
Boundary Value Problems volume 2009, Article number: 491952 (2009)
Abstract
We present an existence result for fourth-order four-point boundary value problem on time scales. Our analysis is based on a fixed point theorem due to Krasnoselskii and Zabreiko.
1. Introduction
Very recently, Karaca [1] investigated the following fourth-order four-point boundary value problem on time scales:

for and
And the author made the following assumptions:
(A1) and
(A2) If
then
The following key lemma is provided in [1].
Lemma 1.1 (see [1, Lemma  2.5]).
Assume that conditions () and (
) are satisfied. If
then the boundary value problem

has a unique solution

where


Here , and
are given as follows:

Unfortunately, this lemma is wrong. Without considering the whole interval the author only considers
in the Green's function
Thus, the expression of
(1.3) which is a solution to BVP (1.2) is incorrect. In fact, if one takes
then (1.1) reduces to the following boundary value problem:

The counterexample is given by [2], from which one can see clearly that [1, Lemma  2.5] is wrong. If one takes , here
is a constant, then (1.1) reduces to the following fourth-order four-point boundary value problem on time scales:

The purpose of this paper is to establish some existence criteria of solution for BVP (1.8) which is a special case of (1.1). The paper is organized as follows. In Section 2, some basic time-scale definitions are presented and several preliminary results are given. In Section 3, by employing a fixed point theorem due to Krasnoselskii and Zabreiko, we establish existence of solutions criteria for BVP (1.8). Section 4 is devoted to an example illustrating our main result.
2. Preliminaries
The study of dynamic equations on time scales goes back to its founder Hilger [3] and it is a new area of still fairly theoretical exploration in mathematics. In the recent years boundary value problem on time scales has received considerable attention [4–6]. And an increasing interest in studying the existence of solutions to dynamic equations on time scales is observed, for example, see [7–16].
For convenience, we first recall some definitions and calculus on time scales, so that the paper is self-contained. For the further details concerning the time scales, please see [17–19] which are excellent works for the calculus of time scales.
A time scale is an arbitrary nonempty closed subset of real numbers
. The operators
and
from
to

are called the forward jump operator and the backward jump operator, respectively.
For all we assume throughout that
has the topology that it inherits from the standard topology on
The notations
and so on, will denote time-scale intervals

where with
Definition 2.1.
Fix Let
Then we define
to be the number (if it exists) with the property that given
there is a neighborhood
of
with

Then is called derivative of
Definition 2.2.
If then we define the integral by

We say that a function is regressive provided

where which is called graininess function. If
is a regressive function, then the generalized exponential function
is defined by

for is the cylinder transformation, which is defined by

Let be two regressive functions, then define

The generalized function has then the following properties.
Lemma 2.3 (see [18]).
Assume that are two regressive functions, then
(i) and
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
The following well-known fixed point theorem will play a very important role in proving our main result.
Theorem 2.4 (see [20]).
Let be a Banach space, and let
be completely continuous. Assume that
is a bounded linear operator such that
is not an eigenvalue of
and

Then has a fixed point in
Throughout this paper, let be endowed with the norm by

where And we make the following assumptions:
() and
() and
()
Set

For convenience, we denote

First, we present two lemmas about the calculus on Green functions which are crucial in our main results.
Lemma 2.5.
Assume that and
are satisfied. If
then
is a solution of the following boundary value problem (BVP):

if and only if

where the Green's function of (2.13) is as follows:

where are given as (2.12), respectively.
Proof.
If is a solution of (2.13), setting

then it follows from the first equation of (2.13) that

Multiplying (2.17) by and integrating from
to
we get

Similarly, by (2.18), we have

Then substituting (2.18) into (2.19), we get for each that

Substituting this expression for into the boundary conditions of (2.13). By some calculations, we get

Then substituting (2.21) into (2.20), we get

By interchanging the order of integration and some rearrangement of (2.22), we obtain

Thus, we obtain (2.14) consequently.
On the other hand, if satisfies (2.14), then direct differentiation of (2.14) yields

And it is easy to know that and
satisfies (2.13).
Corollary 2.6.
If then BVP (2.13) reduces to the following problem:

From Lemma 2.5, BVP (2.25) has a unique solution

where the Green's function of (2.25) is as follows:

where


Proof.
If is a solution of (2.25), take
then
Hence, from (2.20) we have

Substituting this expression for into the boundary conditions of (2.25). By some calculations, we obtain

where is given as (2.28). Then substituting (2.31) into (2.30), we get

where are as in (2.29), respectively. By some rearrangement of (2.32), we obtain (2.26) consequently.
From the proof of Corollary 2.6, if take
we get the following result.
Corollary 2.7.
The following boundary value problem:

has a unique solution

where the Green's function of (2.33) is as follows:

where

After some rearrangement of (2.35), one obtains

Remark 2.8.
Green function (2.37) associated with BVP (2.33) which is a special case of (2.13) is coincident with part of [21, Lemma  1].
Lemma 2.9.
Assume that conditions ()–(
) are satisfied. If
then boundary value problem

has a unique solution

where

and is given in Lemma 2.5.
Proof.
Consider the following boundary value problem:

The Green's function associated with the BVP (2.41) is . This completes the proof.
Remark 2.10.
In [1, Lemma  2.5], the solution of (1.2) is defined as

where and
are given as (1.4) and (1.5), respectively. In fact,
is incorrect. Thus, we give the right form of
as the special case
in our Lemma 2.9.
3. Main Results
Theorem 3.1.
Assume ()–(
) are satisfied. Moreover, suppose that the following condition is satisfied:
where
are continuous,
with

and there exists a continuous nonnegative function such that
If

where

then BVP (1.8) has a solution .
Proof.
Define an operator by

where is given by (2.40). Then by Lemmas 2.5 and 2.9, it is clear that the fixed points of
are the solutions to the boundary value problem (1.8). First of all, we claim that
is a completely continuous operator, which is divided into 3 steps.
Step 1 ( is continuous).
Let be a sequence such that
then we have

Since are continuous, we have
which yields
That is,
is continuous.
Step 2 ( maps bounded sets into bounded sets in
).
Let be a bounded set. Then, for
and any
we have

By virtue of the continuity of and
, we conclude that
is bounded uniformly, and so
is a bounded set.
Step 3 ( maps bounded sets into equicontinuous sets of
).
Let then

The right hand side tends to uniformly zero as Consequently, Steps 1–3 together with the Arzela-Ascoli theorem show that
is completely continuous.
Now we consider the following boundary value problem:

Define

Obviously, is a completely continuous bounded linear operator. Moreover, the fixed point of
is a solution of the BVP (3.8) and conversely.
We are now in the position to claim that is not an eigenvalue of
If and
then (3.8) has no nontrivial solution.
If or
suppose that the BVP (3.8) has a nontrivial solution
and
then we have

which yields

On the other hand, we have

From the above discussion (3.11) and (3.12), we have . This contradiction implies that boundary value problem (3.8) has no trivial solution. Hence,
is not an eigenvalue of
At last, we show that

By then for any
there exist a
such that

Set and select
such that
Denote

Thus for any and
when
it follows that

In a similar way, we also conclude that for any

Therefore,

On the other hand, we get

Combining (3.18) with (3.19), we have

Theorem 2.4 guarantees that boundary value problem (1.8) has a solution It is obvious that
when
for some
In fact, if
then
will lead to a contradiction, which completes the proof.
4. Application
We give an example to illustrate our result.
Example 4.1.
Consider the fourth-order four-pint boundary value problem

Notice that To show that (4.1) has at least one nontrivial solution we apply Theorem 3.1 with
and
Obviously, (
)–(
) are satisfied. And

Since for each
we have the following.
By simple calculation we have

On the other hand, we notice that

Hence,

That is, is satisfied. Thus, Theorem 3.1 guarantees that (4.1) has at least one nontrivial solution
References
Karaca IY: Fourth-order four-point boundary value problem on time scales. Applied Mathematics Letters 2008, 21(10):1057–1063. 10.1016/j.aml.2008.01.001
Bai C, Yang D, Zhu H: Existence of solutions for fourth order differential equation with four-point boundary conditions. Applied Mathematics Letters 2007, 20(11):1131–1136. 10.1016/j.aml.2006.11.013
Hilger S: Analysis on measure chains—a unified approach to continuous and discrete calculus. Results in Mathematics 1990, 18(1–2):18–56.
Atici FM, Guseinov GSh: On Green's functions and positive solutions for boundary value problems on time scales. Journal of Computational and Applied Mathematics 2002, 141(1–2):75–99. 10.1016/S0377-0427(01)00437-X
Benchohra M, Ntouyas SK, Ouahab A: Existence results for second order boundary value problem of impulsive dynamic equations on time scales. Journal of Mathematical Analysis and Applications 2004, 296(1):65–73. 10.1016/j.jmaa.2004.02.057
Boey KL, Wong PJY: Positive solutions of two-point right focal boundary value problems on time scales. Computers & Mathematics with Applications 2006, 52(3–4):555–576. 10.1016/j.camwa.2006.08.025
StehlÃk P: Periodic boundary value problems on time scales. Advances in Difference Equations 2005, (1):81–92.
Sun J-P: Existence of solution and positive solution of BVP for nonlinear third-order dynamic equation. Nonlinear Analysis: Theory, Methods & Applications 2006, 64(3):629–636. 10.1016/j.na.2005.04.046
Sun H-R, Li W-T: Existence theory for positive solutions to one-dimensional
-Laplacian boundary value problems on time scales. Journal of Differential Equations 2007, 240(2):217–248. 10.1016/j.jde.2007.06.004
Su H, Zhang M: Solutions for higher-order dynamic equations on time scales. Applied Mathematics and Computation 2008, 200(1):413–428. 10.1016/j.amc.2007.11.022
Wang D-B, Sun J-P: Existence of a solution and a positive solution of a boundary value problem for a nonlinear fourth-order dynamic equation. Nonlinear Analysis: Theory, Methods & Applications 2008, 69(5–6):1817–1823. 10.1016/j.na.2007.07.028
Yaslan İ: Existence results for an even-order boundary value problem on time scales. Nonlinear Analysis: Theory, Methods & Applications 2009, 70(1):483–491. 10.1016/j.na.2007.12.019
Su Y-H: Multiple positive pseudo-symmetric solutions of
-Laplacian dynamic equations on time scales. Mathematical and Computer Modelling 2009, 49(7–8):1664–1681. 10.1016/j.mcm.2008.10.010
Henderson J, Tisdell CC, Yin WKC: Uniqueness implies existence for three-point boundary value problems for dynamic equations. Applied Mathematics Letters 2004, 17(12):1391–1395. 10.1016/j.am1.2003.08.015
Tian Y, Ge W: Existence and uniqueness results for nonlinear first-order three-point boundary value problems on time scales. Nonlinear Analysis: Theory, Methods & Applications 2008, 69(9):2833–2842. 10.1016/j.na.2007.08.054
Anderson DR, Smyrlis G: Solvability for a third-order three-point BVP on time scales. Mathematical and Computer Modelling 2009, 49(9–10):1994–2001. 10.1016/j.mcm.2008.11.009
Agarwal R, Bohner M, O'Regan D, Peterson A: Dynamic equations on time scales: a survey. Journal of Computational and Applied Mathematics 2002, 141(1–2):1–26. 10.1016/S0377-0427(01)00432-0
Bohner M, Peterson A: Dynamic Equations on Time Scales: An Introduction with Applications. Birkhäuser, Boston, Mass, USA; 2001:x+358.
Bohner M, Peterson A: Advances in Dynamic Equations on Time Scales. Birkhäuser, Boston, Mass, USA; 2003:xii+348.
KrasnoselskiÄ MA, ZabreÄko PP: Geometrical Methods of Nonlinear Analysis, Grundlehren der Mathematischen Wissenschaften. Volume 263. Springer, Berlin, Germany; 1984:xix+409.
Chai G: Existence of positive solutions for second-order boundary value problem with one parameter. Journal of Mathematical Analysis and Applications 2007, 330(1):541–549. 10.1016/j.jmaa.2006.07.092
Acknowledgments
The authors would like to thank the referees for their valuable suggestions and comments. This work is supported by the National Natural Science Foundation of China (10771212) and the Natural Science Foundation of Jiangsu Education Office (06KJB110010).
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Yang, D., Li, G. & Bai, C. Existence of Solutions for Fourth-Order Four-Point Boundary Value Problem on Time Scales. Bound Value Probl 2009, 491952 (2009). https://doi.org/10.1155/2009/491952
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DOI: https://doi.org/10.1155/2009/491952
Keywords
- Unique Solution
- Boundary Value Problem
- Dynamic Equation
- Green Function
- Fixed Point Theorem