El Bakkioui

The book of the general linear group occupies a prominent place in algebra and its applications, as it represents the group of all invertible linear transformations of a finite-dimensional vector space. Within this structure, certain subgroups stand out due to their intrinsic properties, their natural appearance in various contexts, and their profound connections with geometry, analysis, and mathematical physics. These are often referred to as remarkable subgroups of the linear group.This work is devoted to a detailed exploration of these subgroups, with particular emphasis on their definitions, fundamental characteristics, and theoretical significance. Among the most important are the special linear group, which captures the essence of volume-preserving transformations; the orthogonal and unitary groups, which embody notions of symmetry and invariance with respect to quadratic and Hermitian forms; and the symplectic group, which plays a central role in the mathematical formulation of classical and quantum mechanics.