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Three solutions to impulsive differential equations involving p-Laplacian
Advances in Difference Equations volume 2015, Article number: 95 (2015)
Abstract
This paper is concerned with the existence of three solutions of Neumann boundary value problems for impulsive differential equations depending on a parameter λ. We find the range of the control parameter in which the system admits at least three solutions by using an existing three critical points theorem. An example is also given to illustrate our results.
1 Introduction
In this paper, we discuss the following Neumann boundary value problem:
where \(f\in C(J\times R,R)\), \(I_{j}\in C(R,R)\), \(0=t_{0}< t_{1}<t_{2}<\cdots <t_{m}<t_{m+1}=T\), \(\Phi_{p}(s)\) is a p-Laplacian operator with \(\Phi_{p}(s)=|s|^{p-2}s\), \(1< p<+\infty\), \(\Delta\Phi_{p}(u'(t_{j}))= \Phi_{p}(u'(t^{+}_{j}))-\Phi_{p}(u'(t^{-}_{j}))\), where \(u'(t^{+}_{j})\), \(u'(t^{-}_{j})\) denote the right and left limits, respectively, of \(u'(t)\) at \(t=t_{j}\), \(j=1,2,\ldots,m\). \(\lambda\in[0,+\infty)\) is a real parameter.
In recent years, there seems to be increasing interest in the existence of multiple solutions for boundary value problems, we refer the reader to [1–5]. Results on this topic are usually achieved by using various fixed point theorems and degree theory. It is well known that variational methods and critical point theorem are very important tools for dealing with the problems for differential equations and in the last few years, some researchers have gradually paid more attention to applying variational methods to dealing with the existence of solutions for impulsive differential equation boundary value problems [6–11]. But few researches have paid more attention to the existence of three solutions for the system (1.1).
Xie and Luo in [12] have investigated the existence of three solutions to the boundary value problem
Obviously, system (1.2) is a special case of system (1.1) with \(I_{j}=0\). So, the results which are obtained in this paper generalize their results.
The rest of this paper is organized as follows. In Section 2 we present some important lemmas. In Section 3, under suitable hypotheses, we establish that the problem (1.1) possesses at least three solutions, moreover, we present an example to illustrate our results.
2 Preliminaries
In the following, we first introduce some notation.
Put \(H=W^{1,P}([0,T])\) and define
Note that H is a separable and reflexive Banach space.
Definition 2.1
The function \(u:[0,T]\rightarrow\mathbb {R}\) is called a weak solution of problem (1.1) if \(u \in H\) and
for all \(v\in H\).
The following three functions will be used later.
Define \(\Phi:H\rightarrow R\), \(J :H\rightarrow R \) by
where \(F(t,\xi)= \int_{0}^{\xi}f(t,s)\, ds\).
Define \(\varphi:H\rightarrow R\), by
Note that Φ, J, φ are Fréchet differentiable at any \(u\in H\) and
for any \(v\in H\). Further, a critical point of φ by (2.2), gives us a weak solution of the system (1.1).
Lemma 2.2
If function \(u(t)\in H\) is a critical point of the functional φ, then \(u(t)\), \(t\in[0,T]\) is a solution of the system (1.1).
Proof
Let \(u(t)\in H\) be a critical point of functional φ. Then
By integrating (2.3), we have
which holds for all \(v(t)\in H\). For \(j\in\{1,2,\ldots,m\}\), we choose \(v(t)\in H\), with \(v(t)=0\) for every \(t\in[0,t_{j}]\cup[t_{j+1},T]\), then
Therefore,
Thus, u satisfies (1.1).
Combining (2.4), (2.5), and (2.6) we have
If the impulsive condition in (1.1) does not hold, then there exist some \(j\in\{1,2,\ldots,m\}\) such that
Pick \(v(t)= \prod_{i=0,i\neq j}^{m+1}(t-t_{i})\). We have
This is a contradiction. So u satisfies the impulsive condition in (1.1). Therefore, u is a solution of the system (1.1). □
Lemma 2.3
For any \(u(t)\in H\), there exists \(c= 2^{\frac{1}{q}} \max\{ T^{-\frac{1}{p}}, T^{\frac {1}{q}}\}\), \(\frac{1}{p}+\frac{1}{q}=1 \) such that
where \(\|u\|_{\infty}=\max_{t\in[0,T]}|u(t)|\).
Proof
For any \(u(t)\in H\), it follows from the mean value theorem that
for some \(\tau\in[0,T]\). Hence, for \(t \in[0,T]\), using the Hölder inequality,
and we obtain (2.7). □
To verify our main results, we need the following three critical points theorem. For the reader’s convenience we recall here the definition of the weak closure.
Suppose that \(E\subset X\). We denote \(\bar{E}^{w}\) as the weak closure of E, that is, \(x\in\bar{E}^{w}\), if there exists a sequence \(\{x_{n}\}\subset E \) such that \(f(x_{n})\rightarrow f(x) \) for every \(f\in X^{*}\).
Lemma 2.4
([13], Theorem 2.1)
Let X be a separable and reflexive real Banach space. \(\Phi:X\rightarrow R\) is a nonnegative continuously Gâteaux differentiable and sequentially weakly lower semicontinuous functional whose Gâteaux derivative admits a continuous inverse on \(X^{*}\). \(J : X\rightarrow R \) is a continuously Gâteaux differentiable functional whose Gâteaux derivative is compact. Assume that there exists \(x_{0}\in X\) such that \(\Phi(x_{0})=J(x_{0})=0\) and that:
-
(i)
\(\lim_{\|x\|\rightarrow+\infty}(\Phi(x)-\lambda J(x))=+\infty\) for all \(\lambda\in[0,+\infty)\).
Further, assume that there are \(r > 0\), \(x_{1} \in X \) such that:
-
(ii)
\(r<\Phi(x_{1})\).
-
(iii)
\(\sup_{x\in\overline{{\Phi^{-1}((-\infty,r))}}^{w}}J(x)<\frac {r}{r+\Phi(x_{1})}J(x_{1})\).
Then, for each
the equation
has at least three solutions in X, and, moreover, for each \(h>1\), there exists an open interval
and a positive real number σ such that, for each \(\lambda\in \Lambda_{2}\), (2.8) has at least three solutions in X whose norms are less than σ.
3 Main results
In this section, we state our main results and proofs.
Theorem 3.1
Assume that the following conditions hold:
- (H1):
-
There exist two positive constants α, β with \(\alpha< c\beta T^{\frac{1}{p}}\), where c is a constant in (2.7), such that
$$\max_{(t,u)\in[0,T]\times[-\alpha,\alpha]}F(t,u)< \frac{\alpha ^{p}}{T(\alpha^{p}+T(c\beta)^{p}+c^{p}p\sum_{j=1}^{m}\int_{0}^{\beta}I_{j}(s)\, ds)}\int_{0}^{T}F(t, \beta)\, dt. $$ - (H2):
-
There exist constants \(a_{i}>0\) (\(i=1,2\)), \(M>0\), and \(0<\mu<p\) such that
$$F(t,u)\leq a_{1}|u|^{\mu}+a_{2} \quad \textit{for all } |u|\geq M. $$ - (H3):
-
\(\int_{0}^{u}I_{j}(s)\, ds\geq0\), \(s=1,2,\ldots,m\), \(u>0\).
Moreover, put
and for each \(h>1\),
Then, for each
the system (1.1) admits at least three solutions in H and, moreover, for each \(h>1\), there exist an open interval \(\Lambda_{4} \subseteq[0,b]\) and a positive real number σ such that, for each \(\lambda\in\Lambda_{4}\), the system (1.1) admits at least three solutions in H whose norms in H are less than σ.
Proof
Let the space X be the Sobolev space H. By the definitions in (2.1), it is very clear that Φ is a nonnegative Gâteaux differentiable and sequentially weakly lower semicontinuous functional whose Gâteaux derivative admits a continuous inverse on \(X^{*}\), and J is a continuously Gâteaux differentiable functional whose Gâteaux derivative is compact. It is clear that \(\Phi(0)=J(0)=0\).
Secondly, in view of the assumption (H2) and by computing, we have for any \(u\in H\), \(|u|\geq M\) and \(\lambda\geq0\),
From \(0<\mu<p\), we obtain \(\lim_{\|u\|\rightarrow+\infty} \Phi (u)-\lambda J(u)=+\infty\), for all \(\lambda\in[0,+\infty)\). The condition (i) of Lemma 2.4 is satisfied.
Now, we choose
It is clear that \(u_{1}(t)\in H\), and
In view of \(\alpha< c\beta T^{\frac{1}{p}}\), we have
from which the assumption (ii) of Lemma 2.4 is obtained.
Thirdly, we verify that the assumption (iii) of Lemma 2.4 holds.
From Lemma 2.3, the estimate \(\Phi(u)\leq r\) implies that
for all \(t\in[0,T]\). By the definition of r and (3.1), we get
for all \(t\in[0,T]\). This implies
Thus for all \(u\in H\), we have
On the other hand, we have
Therefore, by the assumption (H1), (3.2), and (3.3) we have
which shows the condition (iii) of Lemma 2.4 is satisfied.
Note that
and
By the assumption (H1) we have
This implies
We set
By (3.7), we have \(\varphi_{2}>\varphi_{1}\). By (3.4), (3.5), we apply Lemma 2.4 and find that, for each \(\lambda\in\Lambda_{3}=(\frac{1}{\varphi_{2}},\frac{1}{\varphi_{1}})\), the system (1.1) admits at least three solutions in H.
For each \(h>1\), we take into account that
Taking the condition (H1) into account, it implies that \(b>0\). Then from Lemma 2.4 it follows that, for each \(h>1\), there exist an open interval \(\Lambda_{4}\subseteq[0,b]\) and a real number \(\sigma>0\), such that, for \(\lambda\in\Lambda_{4}\), the system (1.1) admits at least three solutions in H whose norms in H are less than σ. □
We conclude this section with considering the following problem, which is a particular case of the problem (1.1), i.e. the equation is an autonomous system. We have
Corollary 3.2
Assume that the following conditions hold:
- (H′1):
-
There exist two positive constants α, β with \(\alpha< c\beta T^{\frac{1}{p}}\), such that
$$\max_{u\in[-\alpha,\alpha]}F(u)< \frac{\alpha^{p}}{\alpha ^{p}+T(c\beta)^{p}+c^{p}p\sum_{j=1}^{m}\int_{0}^{\beta}I_{j}(s)\, ds}F(\beta). $$ - (H′2):
-
There exist constants \(a'_{i}>0\) (\(i=1, 2\)), \(M>0\), and \(0<\mu <p\) such that
$$F(u)\leq a'_{1}|u|^{\mu}+a'_{2} \quad \textit{for all } |u|\geq M. $$
Moreover, put
and for each \(h>1\),
Then, for each
the system (3.8) admits at least three solutions in H and, moreover, for each \(h>1\), there exist an open interval \(\Lambda_{6} \subseteq[0,b]\) and a positive real number σ such that, for each \(\lambda\in\Lambda_{6}\), the system (3.8) admits at least three solutions in H whose norms in H are less than σ.
Example 3.1
Consider the Neumann boundary value problem
where
It is clear that
and \(c=\sqrt{2}\), \(p=2\), \(T=1\). Let \(\alpha=1\), \(\beta=8\). Direct calculations give
All conditions of Corollary 3.2 are satisfied. So the problem (3.9) admits at least three solutions provided that \(\lambda\in (0.136,0.146)\).
References
Agarwal, RP, O’Regan, D: A multiplicity result for second order impulsive differential equations via the Leggett Williams fixed point theorem. Appl. Math. Comput. 161, 433-439 (2005)
Jiang, LQ, Zhou, Z: Multiple nontrivial solutions for a class of higher dimensional discrete boundary value problems. Appl. Math. Comput. 203, 30-38 (2008)
Liang, SH, Zhang, JH: Positive solutions for singular third-order boundary value problem with dependence on the first order derivative on the half-line. Acta Appl. Math. 111, 27-43 (2010)
Sun, JT, Chen, HB: Multiple positive solutions for multi-point boundary value problems with a p-Laplacian on the half-line. J. Appl. Math. Comput. 33, 173-191 (2010)
Heidarkhani, S, Afrouzi, GA: Some multiplicity results to the existence of three solutions for a Dirichlet boundary value problem involving the p-Laplacian. Math. Model. Anal. 16, 390-400 (2011)
Luo, ZG, Xie, JL, Chen, GP: Existence of solutions of a second-order impulsive differential equation. Adv. Differ. Equ. 2014, 118 (2014)
Xie, JL, Luo, ZG: The existence of solutions of periodic BVP for second order impulsive differential equations. J. Inequal. Appl. 2013, 406 (2013)
Li, JL, Shen, JH: Exsitence of three solutions to impulsive differential equations. J. Integral Equ. Appl. 24, 273-281 (2012)
Marek, G, Szymon, G: On the discrete boundary value problem for anisotropic equation. J. Math. Anal. Appl. 386, 956-965 (2012)
Nieto, JJ, O’Regan, D: Variational approach to impulsive differential equations. Nonlinear Anal., Real World Appl. 10, 680-690 (2009)
Tian, Y, Ge, WG: Applications of variational methods to boundary-value problem for impulsive differential equations. Proc. Edinb. Math. Soc. 51, 509-527 (2008)
Xie, JL, Luo, ZG: Existence of three distinct solutions to boundary value problems of nonlinear differential equations with a p-Laplacian operator. Appl. Math. Lett. 27, 101-107 (2014)
Bonanno, G: A critical points theorem and nonlinear differential problems. J. Glob. Optim. 28, 249-258 (2004)
Acknowledgements
The authors are very grateful to the referees for their very helpful comments and suggestions, which greatly improved the presentation of this paper. This work was partially supported by the Scientific Research Funds of Hunan Provincial Education Department (No. 14C0940 and No. 13K029) and National Natural Science Foundation of P.R. China (No. 11471109).
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Zeng, Y., Xie, J. Three solutions to impulsive differential equations involving p-Laplacian. Adv Differ Equ 2015, 95 (2015). https://doi.org/10.1186/s13662-015-0440-8
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DOI: https://doi.org/10.1186/s13662-015-0440-8
MSC
- 34B15
- 34B18
- 34B37
- 58E30
Keywords
- impulsive differential equations
- critical point theorem
- Neumann boundary value problem