This group gathers the atlas's core theorems of real analysis, the rigorous study of limits, continuity, differentiation, and infinite series on the real line. It covers the foundational results proved in a first course, including the intermediate and mean value theorems, Rolle's theorem, and the fundamental theorem of calculus, together with the theory of sequences and series such as the Bolzano-Weierstrass and Heine-Borel theorems, the calculus of several variables, including the implicit and inverse function theorems, and further classical results on differentiability, convergence, and elementary special functions.