Positive solutions of singular sublinear fourth-order boundary value problems.

We give some necessary and sufficient conditions for the existence of C a 2 [0,1] and C 3 [0,1] positive solutions to the singular boundary value problem where: λ∈  (0,1) is given; and p   :  (0,1)→  [0,∞) can be singular at both ends t   =  0 and t   =  1. We also give a sufficient condition for the existence of C 1 [0,1] positive solutions to the above problem. The proofs are based upon the method of lower and upper solutions for singular fourth-order boundary value problems. [ABSTRACT FROM AUTHOR]