Electronic Journal of Differential Equations, Vol. 2012 (2012), No. 125, pp. 1-6. Title: On Pacard's regularity for the equation $-\Delta u = u^p$ Author: David R. Adams (Univ. of kentucky, Lexington, KY, USA) Abstract: It is shown that the singular set for a positive solution of the PDE $-\Delta u = u^p$ has Hausdorff dimension less than or equal to $n - 2p'$, as conjectured by Pacard [12 in 1993. Submitted June 4, 2012. Published August 02, 2012. Math Subject Classifications: 35D10, 35J60. Key Words: Weak solutions; singular set; regularity.