Journal Home Page Cumulative Index List of all Volumes Complete Contentsof this Volume Previous Article Journal of Lie Theory 22 (2012), No. 3, 839--844Copyright Heldermann Verlag 2012 Reflections on S3 and Quaternionic Möbius Transformations Clarisson Canlubo Institute of Mathematics, University of the Philippines, Diliman, Philippines 1101 crpcanlubo@math.upd.edu.ph Edgar Reyes Dept. of Mathematics, Southeastern Louisiana University, Hammond, LA 70402, U.S.A. ereyes@selu.edu [Abstract-pdf] Let $S^3$ be the set of unit quaternions, let ${\cal H}$ be the algebra of quaternions, and let ${\cal H}^{\ast}$ be the space of pure quaternions. It is an elementary fact that $S^3$ and ${\cal H}^{\ast}\cup \{\infty\}$ are homeomorphic spaces by a stereographic projection. We show that a reflection in $S^3$ induces a linear fractional transformation on ${\cal H}^{\ast}\cup \{\infty\}$ that is defined by a matrix in a symplectic group $Sp(2)$. In addition, we identify the left eigenvalues of such a matrix, and show the subgroup $G$ generated by these matrices satisfies $G/ (\pm I_2)\simeq O(4)$. Keywords: Moebius transformation, quaternion. MSC: 51B10, 15B33 [ Fulltext-pdf  (247  KB)] for subscribers only.