Basheer, Ayoub B.M.Moori, Jamshid2018-07-272018-07-272017Basheer, A.B.M. & Moori, J. 2017. On two groups of the form 28:A9. Afrika Matematika, 28:1011-1032. [https://link.springer.com/article/10.1007/s13370-017-0500-1]1012-94052190-7668 (Online)https://link.springer.com/article/10.1007/s13370-017-0500-1http://hdl.handle.net/10394/30397This paper is dealing with two split extensions of the form 28:A9. We refer to these two groups by G¯¯¯¯1 and G¯¯¯¯2. For G¯¯¯¯1, the 8-dimensional GF(2)-module is in fact the deleted permutation module for A9. We firstly determine the conjugacy classes of G¯¯¯¯1 and G¯¯¯¯2 using the coset analysis technique. The structures of inertia factor groups were determined for the two extensions. The inertia factor groups of G¯¯¯¯1 are A9,A8,S7,(A6×3):2 and (A5×A4):2, while the inertia factor groups of G¯¯¯¯2 are A9,PSL(2,8):3 and 23:GL(3,2). We then determine the Fischer matrices for these two groups and apply the Clifford–Fischer theory to compute the ordinary character tables of G¯¯¯¯1 and G¯¯¯¯2. The Fischer matrices of G¯¯¯¯1 and G¯¯¯¯2 are all integer valued, with sizes ranging from 1 to 9 and from 1 to 4 respectively. The full character tables of G¯¯¯¯1 and G¯¯¯¯2 are 84×84 and 40×40 complex valued matrices respectively.enGroup extensionsAlternating groupInertia groupsFischer matricesCharacter tableArticle