Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2013, Article ID 432941, 8 pages http://dx.doi.org/10.1155/2013/432941 Research Article A Note on Fractional Equations of Volterra Type with Nonlocal Boundary Condition Zhenhai Liu 1,2 and Rui Wang 2 1 Guangxi Key Laboratory of Hybrid Computation and IC Design Analysis, Guangxi University for Nationalities, China 2 College of Sciences, Guangxi University for Nationalities, Nanning, Guangxi 530006, China Correspondence should be addressed to Zhenhai Liu; zhhliu@hotmail.com Received 6 March 2013; Accepted 24 June 2013 Academic Editor: Zhanbing Bai Copyright © 2013 Z. Liu and R. Wang. Tis 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 deal with nonlocal boundary value problems of fractional equations of Volterra type involving Riemann-Liouville derivative. Firstly, by defning a weighted norm and using the Banach fxed point theorem, we show the existence and uniqueness of solutions. Ten, we obtain the existence of extremal solutions by use of the monotone iterative technique. Finally, an example illustrates the results. 1. Introduction Fractional diferential equations arise in many engineering and scientifc disciplines as the mathematical modeling of systems and processes in the felds of physics, chemistry, aerodynamics, and so forth. Tere has been a signifcant theoretical development in fractional diferential equations in recent years (see [118]). Monotone iterative technique is a useful tool for analyzing fractional diferential equations. In [3], Jankowski considered the existence of the solutions of the following problem: ()= (, (),∫ 0 (,)()), 0<<1, ∈(0,], (0)=, (1) where  ∈ ([0,] ×  2 ,), (0) =  1− ()| =0 by using the Banach fxed point theorem and monotone iterative technique. Motivated by [3], in this paper we investigate the follow- ing nonlocal boundary value problem: ()= (, (),∫ 0 (,)()) ≡(), 0<<1,∈(0,], (0)=(), (2) where ∈([0,]× 2 ,), : 1− ([0, ]) →  is a conti- nuous functional,  = [0, ], (0) =  1− ()| =0 , and (,) ∈ (Δ,); here Δ={(,)∈×:0≤≤≤}. Firstly, the nonlocal condition can be more useful than the standard initial condition to describe many phys- ical and chemical phenomena. In contrast to the case for initial value problems, not much attention has been paid to the nonlocal fractional boundary value problems. Some recent results on the existence and uniqueness of nonlocal fractional boundary value problems can be found in [1, 2, 12, 14, 18]. However, discussion on nonlocal boundary value problems of fractional equations of Volterra type involving Riemann-Liouville derivative is rare. Secondly, in [3], in order to discuss the existence and uniqueness of problem (1), Jankowski divided  ∈ (0,1) into two situations to discuss; one is 0 <  ≤ 1/2 with an add- itional condition and the other is 1/2 <  < 1. In this paper, we unify the two situations without using the additional condition. Tirdly, for the study of diferential equation, monotone iterative technique is a useful tool (see [9, 10, 16, 17]). We know that it is important to build a comparison result when we use the monotone iterative technique. We transform the diferential equation into inte- gral equation and use the integral equation to build the comparison result which is diferent from [3]. It makes the calculation easier and is suitable for the more complicated forms of equations.