# Existence of Solutions for a Weighted -Laplacian Impulsive Integrodifferential System with Multipoint and Integral Boundary Value Conditions

- Rong Dong
^{1}, - Yunrui Guo
^{2}, - Yuanzhang Zhao
^{3}and - Qihu Zhang
^{1}Email author

**2010**:392545

https://doi.org/10.1155/2010/392545

© Rong Dong et al. 2010

**Received: **5 October 2010

**Accepted: **15 December 2010

**Published: **21 December 2010

## Abstract

By the Leray-Schauder's degree, the existence of solutions for a weighted -Laplacian impulsive integro-differential system with multi-point and integral boundary value conditions is considered. The sufficient results for the existence are given under the resonance and nonresonance cases, respectively. Moreover, we get the existence of nonnegative solutions at nonresonance.

## 1. Introduction

where and , is called the weighted -Laplacian; , ; , and ; is nonnegative, with ; ; and are linear operators defined by , , , where .

If and , we say the problem is nonresonant, but if and , we say the problem is resonant.

For any , denote . Obviously, is a Banach space with the norm , and is a Banach space with the norm . Denote with the norm , for all , where .

In recent years, there has been an increasing interest in the study of differential equations with nonstandard -growth conditions. These problems have many interesting applications (see [1–4]). Many results have been obtained on these kinds of problems, for example [5–17]. If (a constant), (1.1)–(1.4) becomes the well known -Laplacian problem. If is a general function, one can see easily that in general, while , so represents a non-homogeneity and possesses more nonlinearity, thus is more complicated than . For example, we have the following.

(a)In general, the infimum of eigenvalues for the -Laplacian Dirichlet problems is zero, and only under some special conditions (see [10]). When ( ) is an interval, the results in [10] show that if and only if is monotone. But the property of is very important in the study of -Laplacian problems, for example, in [18], the authors use this property to deal with the existence of solutions.

(b)If and (a constant) and , then is concave, this property is used extensively in the study of one-dimensional -Laplacian problems (see [19]), but it is invalid for . It is another difference between and .

Recently, there are many works devoted to the existence of solutions to the Laplacian impulsive differential equation boundary value problems, for example [20–28]. Many methods had been applied to deal with these problems, for example sub-super-solution method, fixed point theorem, monotone iterative method, coincidence degree, variational principles (see [29]), and so forth. Because of the nonlinearity of , results about the existence of solutions for -Laplacian impulsive differential equation boundary value problems are rare (see [30]). In [31], using coincidence degree method, the present author investigate the existence of solutions for -Laplacian impulsive differential equation with multipoint boundary value conditions. Integral boundary conditions for evolution problems have various applications in chemical engineering, thermoelasticity, underground water flow and population dynamics, there are many papers on the differential equations with integral boundary value problems, for example, [32–35].

where , the impulsive condition (1.8) is called linear impulsive condition (LI for short), and (1.3) is called nonlinear impulsive condition (NLI for short). In generaly, -Laplacian impulsive problems have two kinds of impulsive conditions, that is, LI and NLI.

Let , the function is assumed to be Caratheodory, by this we mean the following:

(i)for almost every the function is continuous;

(ii)for each the function is measurable on ;

(iii)for each there is a such that, for almost every and every with , , , , one has

We say a function is a solution of (1.1) if with absolutely continuous on , , which satisfies (1.1) a.e. on .

This paper is organized as four sections. In Section 2, we present some preliminary and give the operator equation which has the same solutions of (1.1)–(1.4). In Section 3, we give the existence of solutions and nonnegative solutions for system (1.1)–(1.4) at nonresonance. Finally, in Section 4, we give the existence of solutions for system (1.1)–(1.4) at resonance.

## 2. Preliminary

For any , denote . Obviously, has the following properties.

Lemma 2.1 (see [31]).

is a continuous function and satisfies the following.

It is clear that is continuous and sends bounded sets to bounded sets.

We will discuss (2.4) with (1.4) in the cases of resonance and nonresonance, respectively.

### 2.1. The Case of Nonresonance

Denote with the norm , for all , then is a Banach space.

then is continuous. Throughout the paper, we denote . It is easy to see the following.

Lemma 2.2.

It is clear that is continuous and sends bounded sets of to bounded sets of , and hence it is compact continuous.

- (i)
- (ii)

Proof.

it is easy to check that is a continuous operator from to .

We want to show that is a compact set.

Hence the sequence is uniformly bounded and equicontinuous. By Ascoli-Arzela theorem, there exists a subsequence of (which we rename the same) which is convergent in . According to the bounded continuous of the operator , we can choose a subsequence of (which we still denote by ) which is convergent in , then is convergent in .

- (ii)
It is easy to see from (i) and Lemma 2.2.

This completes the proof.

It is easy to see that is compact continuous.

Lemma 2.4.

Proof.

Suppose is a solution of (1.1)–(1.4). From the definition of and , similar to the discussion before Lemma 2.2, we know that is a solution of (2.20).

Conversely, if is a solution of (2.20), then (1.2) is satisfied.

It follows from (2.21) that (1.3) is satisfied.

From (2.21) and the definition of , we have

It follows from (2.22) and (2.23) that (1.4) is satisfied.

Hence is a solutions of (1.1)–(1.4). This completes the proof.

### 2.2. The Case of Resonance

Denote , , . It is easy to see that is dependent on and .

Lemma 2.5.

The function has the following properties.

and hence, if (2.27) has a solution, then it is unique.

Thus the th component of keeps sign on , then it is not hard to check that the th component of keeps the same sign of .

it means the existence of solutions of .

It only remains to prove the continuity of . Let is a convergent sequence in and , as . Since is a bounded sequence, it contains a convergent subsequence . Suppose as . Since , letting , we have , which together with (i) implies , it means is continuous. This completes the proof.

It is clear that is continuous and sends bounded sets of to bounded sets of , and hence it is a compact continuous mapping.

Similar to the proof of Lemma 2.3, we have the following lemma.

Lemma 2.6.

The operator is continuous and sends equiintegrable sets in to relatively compact sets in .

Lemma 2.7.

Proof.

Suppose is a solution of (1.1)–(1.4), it is clear that is a solution of (2.40).

Hence is a solutions of (1.1)–(1.4). This completes the proof.

## 3. Existence of Solutions in the Case of Nonresonance

In this section, we will apply Leray-Schauder's degree to deal with the existence of solutions and nonnegative solutions for system (1.1)–(1.4) at nonresonance.

When satisfies sub- growth condition, we have the following.

Theorem 3.1.

then problem (1.1)−(1.4) has at least one solution.

Proof.

It is easy to see that operator is compact continuous for any . It follows from Lemmas 2.2 and 2.3 that is compact continuous from to for any .

We claim that all the solutions of (3.3) are uniformly bounded for . In fact, if it is false, we can find a sequence of solutions for (3.3) such that as , and for any .

It follows from (3.8) and (3.11) that is uniformly bounded.

which implies that (1.1)–(1.4) has at least one solution. This completes the proof.

Theorem 3.2.

where , and , , then problem (1.1) with (1.2), (1.4), and (1.8) has at least one solution.

Proof.

Since , we have . Thus (3.16) is valid.

There are two cases.

Thus (3.16) is valid.

Thus (3.16) is valid. Thus problem (1.1) with (1.2), (1.4), and (1.8) has at least one solution. This completes the proof.

We have the following.

Theorem 3.3.

then problem (3.21) with (1.2)–(1.4) has at least one solution when the parameter is small enough.

Proof.

We know that (3.25) with (1.2)–(1.4) has the same solution of .

Since , from the proof of Theorem 3.1, we can see that the right hand side is nonzero. Thus (3.21) with (1.2)–(1.4) has at least one solution. This completes the proof.

Theorem 3.4.

where , and , , then problem (3.21) with (1.2), (1.4), and (1.8) has at least one solution when the parameter is small enough.

Proof.

As it is similar to the proof of Theorems 3.2 and 3.3, we omit it here.

In the following, we will consider the existence of nonnegative solutions. For any , the notation means for any .

Theorem 3.5.

Then every solution of (1.1)–(1.4) is nonnegative.

Proof.

It follows from conditions (1^{0})-(2^{0}) and (3.36) that
is increasing on
, namely
, for all
with
. Thus the boundary value condition holds
, then
.

Since is increasing and , we have , for all .

Thus every solution of (1.1)–(1.4) is nonnegative. The proof is completed.

Corollary 3.6.

Under the conditions of Theorem 3.1, we also assume

Then (1.1)–(1.4) has a nonnegative solution.

Proof.

then satisfies Caratheodory condition, and for any .

It is not hard to check that

, for uniformly, where , and ;

It follows from Theorems 3.1 and 3.5 that (3.41) have a nonnegative solution . Since , we have . Thus is a nonnegative solution of (1.1)−(1.4). This completes the proof.

## 4. Existence of Solutions in the Case of Resonance

In the following, we will consider the existence of solutions for system (1.1)–(1.4) at resonance.

Theorem 4.1.

Suppose and , is an open bounded set in such that the following conditions hold.

Then problem (1.1)–(1.4) have a solution on .

Proof.

It means that (4.1) and (4.3) have the same solutions for .

^{0}) it follows that (4.8) has no solutions for . For , (4.3) is equivalent to the following usual problem

^{0}) implies that . Thus we have proved that (4.8) has no solution on . Therefore the Leray-Schauder degree is well defined for , and from the homotopy invariant property of that degree we have

where the function
is defined in (4.2) and
denotes the Brouwer degree. By hypothesis (3^{0}), this last degree is different from zero. This completes the proof.

with (1.2), (1.3), and (1.4), where is Caratheodory, is continuous, and for any fixed , holds , for all , .

Theorem 4.2.

Suppose that the following conditions hold

for all and all , where satisfies ;

the Brouwer degree for large enough , where .

Then problem (4.18) with (1.2), (1.3), and (1.4) has at least one solution.

Proof.

We claim that all the solutions of (4.21) are uniformly bounded for . In fact, if it is false, we can find a sequence of solutions for (4.21) such that as , and for any .

In order to obtaining the existence of solutions (4.18) with (1.2), (1.3), and (1.4), we only need to prove that .

Similar to the preceding discussion, for any , all the solutions of (4.35) are uniformly bounded.

By hypothesis (5^{0}), (4.35) has no solutions on
, from Theorem 4.1, we obtain that (4.18) with (1.2), (1.3), and (1.4) has at least one solution. This completes the proof.

Corollary 4.3.

If
is Caratheodory, conditions (2^{0}), (3^{0}) and (4^{0}) of Theorem 4.2 are satisfied, condition (3^{0}) of Corollary 3.6 is also satisfied,
, where
are positive functions satisfying
; then (4.18) with (1.2), (1.3), and (1.4) has at least one solution.

Proof.

According to Theorem 4.2, we get that (4.18) with (1.2), (1.3), and (1.4) has at least a solution. This completes the proof.

From Theorem 4.2, similar to the proof of Theorem 3.3, we have the following.

Theorem 4.4.

If conditions of (1^{0}) and (3^{0})–(6^{0}) of Theorem 4.2 are satisfied, then problem (4.43) with (1.2), (1.3), and (1.4) has at least one solution when the parameter
is small enough.

Theorem 4.5.

then problem (4.18) with (1.2), (1.3), and (1.8) has at least one solution.

Proof.

Similar to the proof of Theorem 3.2, the condition (4^{0}) of Theorem 4.2 is satisfied. Thus problem (4.18) with (1.2), (1.3) and (1.8) has at least a solution.

Similar to the proof of Theorem 3.2 and Corollary 4.3, we have the following.

Corollary 4.6.

If
is Caratheodory, (4.45), (4.46) and conditions (2^{0}) and (3^{0}) of Theorem 4.2 are satisfied, condition (3^{0}) of Corollary 3.6 is also satisfied,
, where
are positive functions satisfying
; then (4.43) with (1.2), (1.3), and (1.8) has at least one solution when the parameter
is small enough.

## Declarations

### Acknowledgments

This paper is partly supported by the National Science Foundation of China (10701066, 10926075, and 10971087), China Postdoctoral Science Foundation funded project (20090460969), and the Natural Science Foundation of Henan Education Committee (2008-755-65).

## Authors’ Affiliations

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