Electronic Journal of Differential Equations, Vol. 2011 (2011), No. 120, pp. 1-11. Title: Solvability of a second-order multi-point boundary-value problems at resonance on a half-line with dim ker L=2 Authors: Weihua Jiang (Hebei Univ. of Science and Tech., Hebei, China) Bin Wang (Hebei Professional and Tech. College, Hebei, China) Zhenji Wang (Hebei Professional and Tech. College, Hebei, China) Abstract: We show the existence of solutions for a second-order multi-point boundary-value problem at resonance on a half-line, where the dimension of the kernel of the differential operator is 2. Our main tools are the coincidence degree theory due to Mawhin, suitable operators, and algebraic methods. Our results are illustrated with an example. Submitted June 30, 2011. Published September 19, 2011. Math Subject Classifications: 34B10, 34B15. Key Words: Resonance; Fredholm operator; multi-point boundary-value problem; coincidence degree theory.