Abstract
We study the existence of positive solution for the eigenvalue problem of semipositone fractional order differential equation with multipoint boundary conditions by using known Krasnosel'skii's fixed point theorem. Some sufficient conditions that guarantee the existence of at least one positive solution for eigenvalues sufficiently small and sufficiently large are established.
1. Introduction
In this paper, we study the existence of positive solutions to the following eigenvalue problem of semipositone fractional order differential equation with multipoint boundary conditions: where , , , with , is a positive parameter, and are the standard Rieman-Liouville derivative. Throughout the paper, we assume that is semipositone; that is, is continuous and there exists , such that , for any .
The multipoint boundary value problems (BVPs for short) for ordinary differential equations arise in a variety of different applied mathematics and physics. Recently, Feng and Bai [1] investigated the existence of positive solutions for a semipositone second-order multipoint boundary value problem: By using Krasnosel'skii's fixed point theorem, some sufficient conditions that guarantee the existence of at least one positive solution are obtained. In [2], a -type conjugate boundary value problem for the nonlinear fractional differential equation, is considered. Based on the nonlinear alternative of Leray-Schauder type and Krasnosel'skii's fixed-point theorems, the existence of positive solution of the semipositone boundary value problems (3) for a sufficiently small was given. In recent paper [3], Zhang et al. established the existence of multiple positive solutions for a general higher order fractional differential equation with derivatives and a negatively Carathèodory perturbed term: Some local and nonlocal growth conditions were adopted to guarantee the existence of at least two positive solutions for the higher order fractional differential equation (4). For the recent work in application, the reader is referred to [4–20].
Inspired by the above work, in this paper we study the existence of positive solutions to the semipositone BVP (1). Here we also emphasize that the main results of this paper contain not only the cases for sufficiently small, but also for sufficiently large, which is different from [2, 3].
2. Preliminaries and Lemmas
Definition 1 (see [21–24]). The fractional integral of order of a function is given by provided that the right-hand side is pointwisely on .
Definition 2 (see [21–24]). The Riemann-Liouville fractional derivative of order of a function : is given by where , denotes the integer part of the number , and , provided that the right-hand side is defined on .
Lemma 3 (see [21–24]). Assuming that with a fractional derivative of order , then where .
Lemma 4 (see [3]). Suppose that . Then the following boundary value problem has a unique solution where is the Green function of the boundary value problem (8) and
Lemma 5 (see [2]). The function in Lemma 4 has the following properties:(R1), for ;(R2), for ;(R3), for , where
Lemma 6. The following boundary value problem has a unique solution , which satisfies
Proof. By Lemma 4, the unique solution of (13) is So and by , we have , so
The basic space used in this paper is , where is the set of real numbers. Obviously, the space is a Banach space if it is endowed with the norm as follows: for any . Let and then is a cone of .
Now let ; then the boundary value problem (1) is equivalent to the following boundary value problem: Define a modified function for any by and consider
Lemma 7. The BVP (1) and the BVP (22) are equivalent. Moreover, if is a positive solution of the problem (22) and satisfies , , then is a positive solution of the boundary value problem (1).
Proof. Since is a positive solution of the BVP (22) such that for any , we have Let , and then we have Substitute (24) into (23), that is (20), which implies that is a positive solution of the BVP (1).
It follows from Lemma 4 that the BVP (22) is equivalent to the integral equation Thus it is sufficient to find fixed points for the mapping defined by
Lemma 8. is a completely continuous operator.
Proof. For any fixed , there exists a constant such that , and
Take
then
This implies that the operator is bounded.
Next for any , by Lemma 5, we have
On the other hand, it follows from Lemma 5, , and that
So, by (30) and (31), we have
which yields that .
At the end, using standard arguments, according to the Ascoli-Arzela Theorem, one can show that is completely continuous. Thus is a completely continuous operator.
Lemma 9 (see [25]). Let be a real Banach space, and let be a cone. Assume that are two bounded open subsets of with , and let be a completely continuous operator such that either(1) and , or(2) and .Then has a fixed point in .
3. Main Result
Define
Theorem 10. Suppose that Then there exists a constant such that, for any , the BVP (1) has at least one positive solution.
Proof. Choosing with , then
Let
For any , , and sufficiently small such that , we have
Therefore,
On the other hand, take
and choose a large enough such that
By (33), we know that is an unbounded continuous function. Therefore, for any , there exists a constant such that
Choosing
then . Let . Then for any and for any , we have
Consequently, for , it follows from (43) that
and then by (41) and (44), for , we get
So for any and , by (45), we have
Thus, we have
By Lemma 9, has a fixed point such that .
From
we have
Thus
By Lemma 7 and (50), the boundary value problem (1) has at least one positive solution. The proof of Theorem 10 is completed.
Theorem 11. Suppose that and there exist constants and such that Then there exists a constant such that, for any , the BVP (1) has at least one positive solution.
Proof. Choosing
and let . Then for any ,, and , we have
so for any and , by (52)–(55), we have
Thus, we have
According to (51), it is clear that
Let us choose such that
Then there exists a large enough such that
Thus, by (60), if
then
Now denote that
and choose
Then .
Next let . Then for any and for any , we have
which implies that
By Lemma 9, has at least a fixed points such that .
It follows from that
By Lemma 7 and (67), the boundary value problem (1) has at least one positive solution. The proof of Theorem 11 is completed.
Conflict of Interests
The author declares that there is no conflict of interests regarding the publication of this paper.
Acknowledgments
The authors were supported financially by “Chen Guang” Project supported by Shanghai Municipal Education Development Foundation (10CGB25) and Shanghai Universities for Outstanding Young Teachers Scientific Research Selection and Training Special Fund (sjq08011).