Global bifurcation and nodal solutions for fourth-order problems with sign-changing weight

In this paper, we shall establish unilateral global bifurcation result for a class of fourthorder eigenvalue problems with sign-changing weight. Under some natural hypotheses on perturbation function, we show that lk;0 is a bifurcation point of the above problems and there are two distinct unbounded continua, Ck þ and Ck , consisting of the bifurcation branch Ck from lk;0 , wher e lk is the kth positive or negative eigenvalue of the linear problem corresponding to the abov e problems, m 2 fþ; g. As the applications of the above result, we study the existence of nodal solutions for a class of fourth-order eigenvalue problems with sign-changing weight. Moreover, we also establish the Sturm type comparison theorem for fourth-order problems with sign-changing weight. 2013 Elsevier Inc. All rights reserved.