French mathematician known chiefly for his contributions to real analysis (analysis). He is credited with being the founder of the theory of abstract spaces.

Fréchet was professor of mechanics at the University of Poitiers (1910–19) before moving to the University of Strasbourg, where he was professor of higher calculus (1920–27). Joining the faculty of the University of Paris, he served as lecturer on the calculus of probabilities (1928–33), professor of general mathematics (1933–35), professor of differential and integral calculus (1935–40), and professor of the calculus of probabilities (1940–48).

Fréchet made important contributions to the adaptation of the intuitive notions of Euclidean space beyond the study of geometric figures. The resulting abstract spaces (such as metric spaces (metric space), topological spaces (topological space), and vector spaces (vector analysis)) are characterized by their particular elements, axioms, and relationships. In particular, Fréchet devised a method of applying the notion of limits (limit) from calculus to the treatment of functions as elements of a vector space and a way of measuring lengths and distances among the functions to produce a metric space, which led to the profoundly fruitful subject now known as functional analysis (analysis). Fréchet was also a pioneer topologist ( topology is the branch of mathematics dealing with the properties of figures that remain unchanged upon elastic deformation) and contributed notably to statistics and to differential and integral calculus.

His major works include Les Espaces abstraits (1928; “Abstract Spaces”), Récherches théoriques modernes sur la théorie des probabilités (1937–38; “Modern Theoretical Researches on the Theory of Probabilities”), Les Probabilités associées à un système d'évenements compatibles et dependants (1939–43; “The Probabilities Associated with a System of Compatible and Dependent Events”), Pages choisies d'analyse générale (1953; “Chosen Pages of General Analysis”), and Les Mathématiques et le concret (1955; “Mathematics and the Concrete”).