Singular perturbation for nonlinear boundary-value problems.
In this paper we present some new existence results for singular positone and semipositone boundary value problems of second order delay differential equations. Throughout our nonlinearity may be singular in its dependent variable.
This work is devoted to the existence of solutions for a class of singular third-order boundary value problem associated with a -Laplacian operator and posed on the positive half-line; the nonlinearity also depends on the first derivative. The upper and lower solution method combined with the fixed point theory guarantee the existence of positive solutions when the nonlinearity is monotonic with respect to its arguments and may have a space singularity; however no Nagumo type condition is assumed....
In this paper, we are concerned with the existence of solutions of the following multi-point boundary value problem consisting of the higher-order differential equation and the following multi-point boundary value conditions Sufficient conditions for the existence of at least one solution of the BVP and at resonance are established. The results obtained generalize and complement those in [13, 14]. This paper is directly motivated by Liu and Yu [J. Pure Appl. Math. 33 (4)(2002), 475–494...