Class Field Theory
《Class Field Theory》 · 第 8 页 · Chapter 1，Section 1.2.3「Generalized Orthogonal and Lorentz Groups」
The set of $(n+k) imes(n+k)$ real matrices $A$ which preserve this form [...] is the generalized orthogonal group $\mathrm{O}(n;k)$. [...] Of particular interest in physics is the Lorentz group $\mathrm{O}(3;1)$.