Challal, SLyaghfouri, A2025-03-202025-03-202009-04-08S. Challal and A. Lyaghfouri, Porosity of free boundaries in A-obstacle problems, Nonlinear Analysis 70 (2009), no. 7, 2772-2778, DOI 10.1016/j.na.2008.04.002.0362-546X1873-5215https://doi.org/10.1016/j.na.2008.04.002https://hdl.handle.net/10315/42680This post peer review accepted manuscript is published as S. Challal and A. Lyaghfouri, Porosity of free boundaries in A-obstacle problems, Nonlinear Analysis 70 (2009), no. 7, 2772-2778, DOI 10.1016/j.na.2008.04.002. This version is made available under a CC-BY-NC-ND Creative Commons licence.We establish the exact growth of the solution of the A-obstacle problem near the free boundary from which we deduce its porosity.enAttribution-NonCommercial-NoDerivatives 4.0 InternationalApplied mathematicsMathematical sciencesA-obstacle problemA-LaplacianOrlicz Sobolev spacesFree boundaryPorosityArticle