LAUSR

This article recalls some facts about the conformal group $${{\rm Conf}(V, Q)}$$Conf(V,Q) of a quadratic space (V, Q); in particular, there is a surjective group morphism $${{\rm O}(V^{\dag}, Q^{\dag}) \rightarrow {\rm Conf}(V, Q)}$$O(V†,Q†)→Conf(V,Q), where $${(V^{\dag}, Q^{\dag})}$$(V†,Q†) is the orthogonal sum of (V, Q) and a hyperbolic plane; its kernel is a group of order two. Then it explains how the elements of $${{\rm O}(V^{\dag}, Q^{\dag})}$$O(V†,Q†) and $${{\rm Conf}(V, Q)}$$Conf(V,Q) can be represented by Vahlen matrices. And finally, it recalls some properties of Vahlen matrices.