University of Isfahan International Journal of Group Theory 2251-7650 2 1 2013 03 01 On some invariants of finite groups 109 115 2642 10.22108/ijgt.2013.2642 EN Jan Krempa Institute of Mathematics, University of Warsaw Agnieszka Stocka Institute of Mathematics University of Białystok Journal Article 2012 12 18 A normal subgroup $N$ of a group $G$ is said to be an‎ <em>omissible</em> subgroup of $G$ if it has the following property‎: ‎whenever $X\leq G$ is such that $G=XN$‎, ‎then $G=X$‎. ‎In this note we construct various groups $G$‎, ‎each of which has an omissible subgroup $N\neq 1$ such that $G/N\cong SL_2(k)$ where $k$ is a field of positive characteristic‎. https://ijgt.ui.ac.ir/article_2642_9f742c032856a8f0dcd5a8b7de56b25b.pdf