Hindawi Publishing Corporation International Journal of Differential Equations Volume 2011, Article ID 401803, 14 pages doi:10.1155/2011/401803 Research Article The Existence of Solutions for a Nonlinear Fractional Multi-Point Boundary Value Problem at Resonance Xiaoling Han and Ting Wang Department of Mathematics, Northwest Normal University, Lanzhou 730070, China Correspondence should be addressed to Xiaoling Han, hanxiaoling@nwnu.edu.cn Received 16 May 2011; Accepted 16 June 2011 Academic Editor: Nikolai Leonenko Copyright q 2011 X. Han and T. Wang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We discuss the existence of solution for a multipoint boundary value problem of fractional differential equation. An existence result is obtained with the use of the coincidence degree theory. 1. Introduction In this paper, we study the multipoint boundary value problem α α−1 α−2 D0 ut f t, ut, D0 ut, D0 ut et, 3−α I0 u0 0, α−2 D0 u0 n α−2 βj D0 u ξj , 0 < t < 1, u1 j1 m αi u ηi , 1.1 1.2 i1 where 2 < α ≤ 3, 0 < ξ1 < ξ2 < · · · < ξn < 1, n ≥ 1, 0 < η1 < · · · < ηm < 1, m ≥ 2, αi , βj ∈ R, m i1 αi ηiα−1 m αi ηiα−2 1, n βj ξj 0, n i1 j1 j1 βj 1, 1.3 2 International Journal of Differential Equations α α and I0 are the f : 0, 1 × R3 → R satisfying the Carathéodory conditions, e ∈ L1 0, 1. D0 standard Riemann-Liouville derivative and integral, respectively. We assume, in addition, that n m Γα2 Γα − 1 α 2α−1 βj ξ 1 − αi ηi R Γ2αΓα 1 j1 j i1 n m Γα2 Γα − 1 α1 2α−2 1 − αi ηi − βj ξ Γα 2Γ2α − 1 j1 j i1 1.4 / 0, where Γ is the Gamma function. Due to condition 1.3, the fractional differential operator in 1.1, 1.2 is not invertible. Fractional differential equation can describe many phenomena in various fields of science and engineering. Many methods have been introduced for solving fractional differential equations, such as the popular Laplace transform method, the iteration method. For details, see 1, 2 and the references therein. Recently, there are some papers dealing with the solvability of nonlinear boundary value problems of fractional differential equation, by use of techniques of nonlinear analysis fixed-point theorems, Leray-Schauder theory, etc., see, for example, 3–6. But there are few papers that consider the fractional-order boundary problems at resonance. Very recently 7, Y. H. Zhang and Z. B. Bai considered the existence of solutions for the fractional ordinary differential equation α−n−1 α α−1 ut f t, ut, D0 ut, . . . , D0 ut et, D0 0 < t < 1, 1.5 subject to the following boundary value conditions: α−n−1 n−α I0 u0 D0 α−2 u0 · · · D0 u0 0, u1 σu η , 1.6 where n > 2 is a natural number, n − 1 < α ≤ n is a real number, f : 0, 1 × Rn → R is continuous, and e ∈ L1 0, 1, σ ∈ 0, ∞, and η ∈ 0, 1 are given constants such that σηα−1 1. α α and I0 are the standard Riemann-Liouville derivative and integral, respectively. By the D0 conditions, the kernel of the linear operator is one dimensional. Motivated by the above work and recent studies on fractional differential equations 8–18, in this paper, we consider the existence of solutions for multipoint boundary value problem 1.1, 1.2 at resonance. Note that under condition 1.3, the kernel of the linear operator in 1.1, 1.2 is two dimensional. Our method is based upon the coincidence degree theory of Mawhin 18. Now, we will briefly recall some notation and abstract existence result. Let Y, Z be real Banach spaces, let L : domL ⊂ Y → Z be a Fredholm map of index zero, and let P : Y → Y, Q : Z → Z be continuous projectors such that ImP KerP , KerQ ImL, and Y KerL ⊕ KerP , Z ImL ⊕ ImQ. It follows that L|domL∩KerP : domL ∩ KerP → ImL is invertible. We denote the inverse of the map by International Journal of Differential Equations 3 ∅, the map N : Y → Z will be KP . If Ω is an open-bounded subset of Y such that domL∩Ω / called L-compact on Ω if QNΩ is bounded and KP I − QN : Ω → Y is compact. The theorem that we used is Theorem 2.4 of 18. Theorem 1.1. Let L be a Fredholm operator of index zero and N be L-compact on Ω. Assume that the following conditions are satisfied: i Lx / λNx for every x, λ ∈ domL \ KerL ∩ ∂Ω × 0, 1, ii Nx ∈ / ImL for every x ∈ KerL ∩ ∂Ω, iii degJQN|KerL , Ω ∩ KerL, 0 / 0, where Q : Z → Z is a projection as above with ImL KerQ, and J : ImQ → KerL is any isomorphism, then the equation Lx Nx has at least one solution in domL ∩ Ω. The rest of this paper is organized as follows. In Section 2, we give some notation and Lemmas. In Section 3, we establish an existence theorem of a solution for the problem 1.1, 1.2. 2. Background Materials and Preliminaries For the convenience of the reader, we present here some necessary basic knowledge and definitions for fractional calculus theory, and these definitions can be found in the recent literature 1, 2. Definition 2.1. The fractional integral of order α > 0 of a function y : 0, ∞ → R is given by α yt I0 1 Γα t t − sα−1 ysds, 2.1 0 0 provided the right side is pointwise defined on 0, ∞. And we let I0 yt yt for every continuous y : 0, ∞ → R. Definition 2.2. The fractional derivative of order α > 0 of a function y : 0, ∞ → R is given by α yt D0 n t ys d 1 ds, α−n1 Γn − α dt 0 t − s 2.2 where n α 1, provided the right side is pointwise defined on 0, ∞. Lemma 2.3 see 3. Assume that u ∈ C0, 1 ∩ L1 0, 1 with a fractional derivative of order α > 0 that belongs to C0, 1 ∩ L1 0, 1, then α α I0 D0 ut ut C1 tα−1 C2 tα−2 · · · CN tα−N , for some Ci ∈ R, i 1, 2, . . . , N, where N is the smallest integer greater than or equal to α. 2.3 4 International Journal of Differential Equations We use the classical space C0, 1 with the norm x∞ maxt∈0,1 |xt|. Given μ > 0 and N μ 1, one can define a linear space μ Cμ 0, 1 : u | ut I0 xt c1 tμ−1 c2 tμ−2 · · · cN−1 tμ−N−1 , t ∈ 0, 1 , 2.4 where x ∈ C0, 1 and ci ∈ R, i 1, 2, . . . , N − 1. By means of the linear function analysis μ μ−N−1 u∞ u∞ , Cμ 0, 1 theory, one can prove that with the norm uCμ D0 u∞ · · ·D0 is a Banach space. Lemma 2.4 see 7. F ⊂ Cμ 0, 1 is a sequentially compact set if and only if F is uniformly bounded and equicontinuous. Here, uniformly bounded means that there exists M > 0 such that for every u ∈ F, μ μ−N−1 u u∞ < M, 2.5 uCμ D0 u · · · D0 ∞ ∞ and equicontinuous means that for all ε > 0, ∃δ > 0 such that |ut1 − ut2 | < ε, ∀t1 , t2 ∈ 0, 1, |t1 − t2 | < δ, ∀u ∈ F, 2.6 α−i α−i ut2 < ε, t1 , t2 ∈ 0, 1, |t1 − t2 | < δ, ∀u ∈ F, ∀i ∈ {0, . . . , N − 1}. D0 ut1 − D0 1 α−1 xt Let Z L1 0, 1 with the norm g1 0 |gs|ds. Y Cα−1 0, 1 {u | ut I0 α−1 α−2 α−2 ct , t ∈ 0, 1}, where x ∈ C0, 1, c ∈ R, with the norm uCα−1 D0 u∞ D0 u∞ u∞ , and Y is a Banach space. Definition 2.5. By a solution of the boundary value problem 1.1, 1.2, we understand a α−1 u is absolutely continuous on 0, 1 and satisfies 1.1, function u ∈ Cα−1 0, 1 such that D0 1.2. Definition 2.6. We say that the map f : 0, 1 × R → R satisfies the Carathéodory conditions with respect to L1 0, 1 if the following conditions are satisfied: i for each z ∈ R, the mapping t → ft, z is Lebesgue measurable, ii for almost every t ∈ 0, 1, the mapping z → ft, z is continuous on R, iii for each r > 0, there exists ρr ∈ L1 0, 1, R such that, for a.e., t ∈ 0, 1 and every |z| ≤ r, we have |ft, z| ≤ ρr t. Define L to be the linear operator from domL ∩ Y to Z with α domL u ∈ Cα−1 0, 1 | D0 u ∈ L1 0, 1, u satisfies 1.2 , α Lu D0 u, 2.7 u ∈ domL. We define N : Y → Z by setting α−1 α−2 Nut f t, ut, D0 ut, D0 ut et. 2.8 International Journal of Differential Equations 5 Then boundary value problem 1.1, 1.2 can be written as Lu Nu. 2.9 Lemma 2.7. Let condition 1.3 and 1.4 hold, then L : domL ∩ Y → Z is a Fredholm map of index zero. Proof. It is clear that KerL {atα−1 btα−2 | a, b ∈ R} ∼ R2 . Let g ∈ Z and 1 ut Γα t t − sα−1 gsds c1 tα−1 c2 tα−2 , 2.10 0 α then D0 ut gt a.e., t ∈ 0, 1 and, if 1 1 − sα−1 gsds − 0 m ηi αi ξj βj ηi − s α−1 gsds 0, 0 i1 n 2.11 ξj − s gsds 0 0 j1 hold. Then ut satisfies the boundary conditions 1.2, that is, u ∈ domL, and we have g ∈ Z | g satisfies 2.11 ⊆ ImL. 2.12 α Let u ∈ domL, then for D0 u ∈ ImL, we have α α ut I0 D0 ut c1 tα−1 c2 tα−2 c3 tα−3 , 2.13 α which, due to the boundary value condition 1.2, implies that D0 u satisfies 2.11. In fact, m 3−α from I0 u0 0, we have c3 0, from u1 i1 αi uηi , we have 1 1 − s 0 α−2 and from D0 u0 α−1 α D0 usds − m ηi αi i1 n j1 0 ηi − s α−1 α D0 usds 0, 2.14 α−2 βj D0 uξj , we have ξj n α βj usds 0. ξj − s D0 j1 2.15 0 Hence, ImL ⊆ g ∈ Z | g satisfies 2.11 . 2.16 6 International Journal of Differential Equations Therefore, ImL g ∈ Z | g satisfies 2.11 . 2.17 Consider the continuous linear mapping Q1 : Z → Z and Q2 : Z → Z defined by Q1 g 1 1 − sα−1 gsds − 0 m ηi i1 α−1 ηi − s αi gsds, 0 ξj n βj Q2 g ξj − s gsds. 2.18 0 j1 Using the above definitions, we construct the following auxiliary maps R1 , R2 : Z → Z: ⎤ ⎡ n m 1 ⎣ Γα − 1 ΓαΓα − 1 α 2α−2 Q2 gt⎦, 1 − αi ηi βj ξ Q1 gt − R1 g R Γα 1 j1 j Γ2α − 1 i1 ⎡ n Γα 1 Γα2 R2 g − ⎣ βj ξjα1 Q1 gt − R Γα 2 j1 Γ2α ⎤ m 2α−1 Q2 gt⎦. 1 − αi ηi 2.19 i1 Since the condition 1.4 holds, the mapping Q : Z → Z defined by Qy t R1 gt tα−1 R2 gt tα−2 2.20 is well defined. Recall 1.4 and note that R1 R1 gt α−1 ⎡ n 1 ⎣ Γα − 1 βj ξjα Q1 R1 gtα−1 R Γα 1 j1 − ΓαΓα − 1 Γ2α − 1 ⎤ m 1 − αi ηi2α−2 Q2 R1 gtα−1 ⎦ i1 ⎡ n m 1 ⎣ Γα − 1Γ α2 α 2α−1 βj ξ 1 − αi ηi R1 g R Γα 1Γ2α j1 j i1 ⎤ m n Γα − 1Γ α2 1 − αi ηi2α−2 − βj ξjα1 ⎦ Γ2α − 1Γα 2 i1 j1 R1 g, 2.21 International Journal of Differential Equations 7 and similarly we can derive that R1 R2 gtα−2 0, R2 R1 gtα−1 0, 2.22 R2 R2 gtα−2 R2 g. So, for g ∈ Z, it follows from the four relations above that Q2 g R1 R1 gtα−1 R2 gtα−2 tα−1 R2 R1 gtα−1 R2 gtα−2 tα−2 R1 R1 gtα−1 tα−1 R1 R2 gtα−2 tα−1 R2 R1 gtα−1 tα−2 R2 R2 gtα−2 tα−2 R1 gt α−1 R2 gt 2.23 α−2 Qg, that is, the map Q is idempotent. In fact, Q is a continuous linear projector. Note that g ∈ ImL implies Qg 0. Conversely, if Qg 0, then we must have R1 g R2 g 0; since the condition 1.4 holds, this can only be the case if Q1 g Q2 g 0, that is, g ∈ ImL. In fact, ImL KerQ. Take g ∈ Z in the form g g − Qg Qg, so that g − Qg ∈ ImL KerQ and Qg ∈ ImQ. Thus, Z ImL ImQ. Let g ∈ ImL ∩ ImQ and assume that gs asα−1 bsα−2 is not identically zero on 0, 1, then, since g ∈ ImL, from 2.11 and the condition 1.4, we derive a b 0, which is a contradiction. Hence, ImL ∩ ImQ {0}; thus, Z ImL ⊕ ImQ. Now, dim KerL 2 co dim ImL, and so L is a Fredholm operator of index zero. Let P : Y → Y be defined by P ut 1 1 α−1 D0 Dα−2 u0tα−2 , u0tα−1 Γα Γα − 1 0 t ∈ 0, 1. 2.24 Note that P is a continuous linear projector and α−1 α−2 KerP u ∈ Y | D0 u0 D0 u0 0 . 2.25 It is clear that Y KerL ⊕ KerP . Note that the projectors P and Q are exact. Define KP : ImL → domL ∩ KerP by 1 KP gt Γα t 0 α gt. t − sα−1 gsds I0 2.26 8 International Journal of Differential Equations Hence, we have α−1 D0 KP g t t α−2 D0 KP g t gsds, 0 t t − sgsds, 2.27 0 α−1 α−2 KP g∞ ≤ g1 , D0 KP g∞ ≤ g1 , and thus then KP g∞ ≤ 1/Γαg1 , D0 KP g α−1 ≤ C 2 1 g . 1 Γα 2.28 α α In fact, if g ∈ ImL, then LKP g D0 I0 g g. Also, if u ∈ domL ∩ KerP , then α α D0 gt gt c1 tα−1 c2 tα−2 c3 tα−3 , KP Lg t I0 2.29 from boundary value condition 1.2 and the fact that u ∈ domL ∩ KerP , we have c1 c2 c3 0. Thus, −1 KP L|domL∩KerP . 2.30 QNut R1 Nutα−1 R2 Nutα−2 , 1 1 KP I − QNut t − sα−1 Nus − QNusds. Γα 0 2.31 Using 2.19, we write With arguments similar to those of 7, we obtain the following Lemma. Lemma 2.8. KP I−Q N : Y → Y is completely continuous. 3. The Main Results Assume that the following conditions on the function ft, x, y, z are satisfied: H1 there exists a constant A > 0, such that for u ∈ domL \ KerL satisfying α−1 α−2 ut| |D0 ut| > A for all t ∈ 0, 1, we have |D0 Q1 Nut / 0 or Q2 Nut / 0, 3.1 International Journal of Differential Equations 9 H2 there exist functions a, b, c, d, r ∈ L1 0, 1 and a constant θ ∈ 0, 1 such that for all x, y, z ∈ R3 and a.e., t ∈ 0, 1, one of the following inequalities is satisfied: f t, x, y, z ≤ at|x| bty ct|z| dt|z|θ rt, f t, x, y, z ≤ at|x| bty ct|z| dtyθ rt, f t, x, y, z ≤ at|x| bty ct|z| dt|x|θ rt, 3.2 H3 there exists a constant B > 0 such that for every a, b ∈ R satisfying a2 b2 > B, then either aR1 N atα−1 btα−2 bR2 N atα−1 btα−2 < 0, 3.3 aR1 N atα−1 btα−2 bR2 N atα−1 btα−2 > 0. 3.4 or else Remark 3.1. R1 Natα−1 btα−2 and R2 Natα−1 btα−2 from H3 stand for the images of ut atα−1 btα−2 under the maps R1 N and R2 N, respectively. Theorem 3.2. If (H1)–(H3) hold, then boundary value problem 1.1-1.2 has at least one solution provided that a1 b1 c1 < 1 , τ 3.5 where τ 5 2/Γα 1/Γα − 1. Proof. Set Ω1 {u ∈ domL \ KerL | Lu λNu for some λ ∈ 0, 1}, 3.6 0, Nu ∈ ImL KerQ, and hence QNut 0 for all then for u ∈ Ω1 , Lu λNu; thus, λ / t ∈ 0, 1. By the definition of Q, we have Q1 Nut Q2 Nut 0. It follows from H1 that α−1 α−2 ut0 | |D0 ut0 | ≤ A. Now, there exists t0 ∈ 0, 1 such that |D0 α−1 D0 ut α−2 ut D0 α−1 D0 ut0 α−2 D0 ut0 t t0 t t0 α D0 usds, 3.7 α−1 D0 usds, 10 International Journal of Differential Equations so α−1 α−1 ut D0 u0 ≤ D0 ∞ α−1 α ≤ D0 ut0 D0 u 1 ≤ A Lu1 ≤ A Nu1 , α−2 α−2 ut D0 u0 ≤ D0 3.8 ∞ α−1 α−2 ≤ D0 ut0 D0 u ∞ α−1 α−2 α ≤ D0 ut0 D0 ut0 D0 u 1 ≤ A Lu1 ≤ A Nu1 . Now by 3.8, we have P uCα−1 1 1 α−1 α−1 α−2 α−2 D u0t D u0t Γα 0 Γα − 1 0 Cα−1 1 1 α−1 α−1 α−2 α−2 Γα D0 u0t Γα − 1 D0 u0t ∞ α−1 α−1 α−2 D0 u0 D0 u0t D0 u0 ∞ ∞ 3.9 1 1 α−1 α−2 D0 u0 1 D0 u0 Γα Γα − 1 1 1 ≤ 2 A Nu1 1 A Nu1 . Γα Γα − 1 ≤ 2 Note that I − P u ∈ ImKP domL ∩ KerP for u ∈ Ω1 , then, by 2.28 and 2.30, I − P uCα−1 KP LI − P Cα−1 1 ≤ 2− LI − P u1 Γα 1 2− Lu1 Γα 1 ≤ 2− Nu1 . Γα 3.10 International Journal of Differential Equations 11 Using 3.9 and 3.10, we obtain uCα−1 P u I − P uCα−1 ≤ P uCα−1 I − P uCα−1 1 1 1 A Nu1 1 A Nu1 2 Nu1 Γα Γα − 1 Γα 1 1 2 1 A 5 Nu1 3 Γα Γα − 1 Γα Γα − 1 ≤ 2 τNu1 C1 , 3.11 where C1 3 1/Γα 1/Γα − 1A is a constant. This is for all u ∈ Ω1 , uCα−1 ≤ τNu1 C1 . 3.12 If the first condition of H2 is satisfied, then we have α−1 α−2 u , D0 u max u∞ , D0 ∞ ∞ α−1 α−2 ≤ uCα−1 ≤ τ a1 u∞ b1 D0 u c1 D0 u ∞ ∞ 3.13 α−2 θ d1 D0 u r1 e1 C1 , ∞ and consequently, u∞ ≤ τ α−1 α−2 α−2 θ u c1 D0 u d1 D0 u r1 e1 b1 D0 ∞ ∞ ∞ 1 − a1 τ C1 , 1 − a1 τ α−1 D0 u ≤ ∞ τ α−2 α−2 θ u d1 D0 u r1 e1 c1 D0 ∞ ∞ 1 − a1 τ − b1 τ C1 , 1 − a1 τ − b1 τ α−1 D0 u ≤ ∞ α−2 θ τd1 D0 u∞ 1 − a1 τ − b1 τ − c1 τ τr1 e1 C1 . 1 − a1 τ − b1 τ − c1 τ 3.14 3.15 3.16 12 International Journal of Differential Equations α−1 u∞ ≤ Note that θ ∈ 0, 1 and a1 b1 c1 < 1/τ, so there exists M1 > 0 such that D0 M1 for all u ∈ Ω1 . The inequalities 3.14 and 3.15 show that there exist M2 , M3 > 0 such α−1 u∞ ≤ M2 , u∞ ≤ M3 for all u ∈ Ω1 . Therefore, for all u ∈ Ω1 , uCα−1 u∞ that D0 α−1 α−2 u∞ ≤ M1 M2 M3 , that is, Ω1 is bounded given the first condition of D0 u∞ D0 H2. If the other conditions of H2 hold, by using an argument similar to the above, we can prove that Ω1 is also bounded. Let Ω2 {u ∈ KerL | Nu ∈ ImL}. 3.17 For u ∈ Ω2 , u ∈ KerL {u ∈ domL | u atα−1 btα−2 , a, b ∈ R, t ∈ 0, 1}, and QNatα−1 btα−2 0; thus, R1 Natα−1 btα−2 R2 Natα−1 btα−2 0. By H3, a2 b2 ≤ B, that is, Ω2 is bounded. We define the isomorphism J : ImQ → KerL by J atα−1 btα−2 atα−1 btα−2 , a, b ∈ R. 3.18 If the first part of H3 is satisfied, let Ω3 u ∈ Ker L : −λJ −1 u 1 − λQNu 0, λ ∈ 0, 1 . 3.19 For every atα−1 btα−2 ∈ Ω3 , λ atα−1 btα−2 1 − λ R1 N atα−1 btα−2 tα−1 R2 N atα−1 btα−2 tα−2 . 3.20 If λ 1, then a b 0, and if a2 b2 > B, then by H3, λ a2 b2 1 − λ aR1 N atα−1 btα−2 bR2 N atα−1 btα−2 < 0, 3.21 which, in either case, obtain a contradiction. If the other part of H3 is satisfied, then we take Ω3 u ∈ Ker L : λJ −1 u 1 − λQNu 0, λ ∈ 0, 1 , 3.22 and, again, obtain a contradiction. Thus, in either case, α−1 α−2 u D0 u uCα−1 u∞ D0 atα−1 btα−2 ∞ ∞ Cα−1 atα−1 btα−2 aΓα∞ aΓαt bΓα − 1∞ ∞ ≤ 1 2Γα|a| 1 Γα − 1|b| ≤ 2 2Γα Γα − 1|a|, 3.23 International Journal of Differential Equations 13 for all u ∈ Ω3 , that is, Ω3 is bounded. In the following, we will prove that all the conditions of Theorem 1.1 are satisfied. 3 Set Ω to be a bounded open set of Y such that Ui1 Ωi ⊂ Ω. by Lemma 2.8, the operator KP I − QN : Ω → Y is compact; thus, N is L-compact on Ω, then by the above argument, we have i Lu / λNx, for every u, λ ∈ domL \ Ker L ∩ ∂Ω × 0, 1, ii Nu ∈ / ImL, for every u ∈ KerL ∩ ∂Ω. Finally, we will prove that iii of Theorem 1.1 is satisfied. Let Hu, λ ±Iu 1 − λJQNu, where I is the identity operator in the Banach space Y . According to the above argument, we know that Hu, λ / 0, ∀u ∈ ∂Ω ∩ KerL, 3.24 and thus, by the homotopy property of degree, deg JQN|KerL , Ω ∩ KerL, 0 degH. . . , 0, Ω ∩ KerL, 0 degH. . . , 1, Ω ∩ KerL, 0 3.25 deg±I, Ω ∩ KerL, 0 ±1 / 0, then by Theorem 1.1, Lu Nu has at least one solution in domL ∩ Ω, so boundary problem 1.1, 1.2 has at least one solution in the space Cα−1 0, 1. The proof is finished. Acknowledgments This work is supported by the NSFC no. 11061030, no. 11026060, the Fundamental Research Funds for the Gansu Universities, the nwnu-kjcxgc-03-69, nwnu-kjcxgc-03-61. References 1 A. A. Kilbas, H. M. Srivastava, and J. J. Trujillo, Theory and Applications of Fractional Differential Equations, Elsevier, Amsterdam, The Netherlands, 2006. 2 K. S. Miller, “Fractional differential equations,” Journal of Fractional Calculus, vol. 3, pp. 49–57, 1993. 3 Z. Bai and H. Lü, “Positive solutions for boundary value problem of nonlinear fractional differential equation,” Journal of Mathematical Analysis and Applications, vol. 311, no. 2, pp. 495–505, 2005. 4 A. Babakhani and V. Daftardar-Gejji, “Existence of positive solutions of nonlinear fractional differential equations,” Journal of Mathematical Analysis and Applications, vol. 278, no. 2, pp. 434–442, 2003. 5 V. Daftardar-Gejji and A. Babakhani, “Analysis of a system of fractional differential equations,” Journal of Mathematical Analysis and Applications, vol. 293, no. 2, pp. 511–522, 2004. 6 F. Meng and Z. Du, “Solvability of a second-order multi-point boundary value problem at resonance,” Applied Mathematics and Computation, vol. 208, no. 1, pp. 23–30, 2009. 14 International Journal of Differential Equations 7 Y. H. Zhang and Z. B. Bai, “Exitence of solutions for nonlinear fractional three-point boundary value problem at resonance,” Journal of Applied Mathematics and Computing, vol. 36, no. 1-2, pp. 417–440, 2011. 8 H. Jafari and V. Daftardar-Gejji, “Positive solutions of nonlinear fractional boundary value problems using Adomian decomposition method,” Applied Mathematics and Computation, vol. 180, no. 2, pp. 700–706, 2006. 9 C. Yu and G. Z. Gao, “On the solution of nonlinear fractional order differential equation,” Nonlinear Analysis, vol. 63, no. 5–7, pp. e971–e976, 1998. 10 N. Kosmatov, “A multi-point boundary value problem with two critical conditions,” Nonlinear Analysis, vol. 65, no. 3, pp. 622–633, 2006. 11 B. Liu and Z. Zhao, “A note on multi-point boundary value problems,” Nonlinear Analysis, vol. 67, no. 9, pp. 2680–2689, 2007. 12 R. P. Agarwal, V. Lakshmikantham, and J. J. Nieto, “On the concept of solution for fractional differential equations with uncertainty,” Nonlinear Analysis, vol. 72, no. 6, pp. 2859–2862, 2010. 13 Y.-K. Chang and J. J. Nieto, “Some new existence results for fractional differential inclusions with boundary conditions,” Mathematical and Computer Modelling, vol. 49, no. 3-4, pp. 605–609, 2009. 14 A. M. A. El-Sayed, “Nonlinear functional-differential equations of arbitrary orders,” Nonlinear Analysis, vol. 33, no. 2, pp. 181–186, 1998. 15 D. Guo and J. Sun, Nonlinear Integral Equations, Shandong Science and Technology Press, Jinan, China, 1987. 16 V. Lakshmikantham and S. Leela, “Nagumo-type uniqueness result for fractional differential equations,” Nonlinear Analysis, vol. 71, no. 7-8, pp. 2886–2889, 2009. 17 V. Lakshmikantham and S. Leela, “A Krasnoselskii-Krein-type uniqueness result for fractional differential equations,” Nonlinear Analysis, vol. 71, no. 7-8, pp. 3421–3424, 2009. 18 J. Mawhin, “Topological degree and boundary value problems for nonlinear differential equations,” in Topological Methods for Ordinary Differential Equations, P. M. Fitzpatrick, M. Martelli, J. Mawhin, and R. Nussbaum, Eds., vol. 1537 of Lecture Notes in Mathematics, pp. 74–142, Springer, Berlin, Germany, 1991. 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