Rham

Rham is a term that can refer to several topics in mathematics, botany, and onomastics. In mathematics, it is commonly encountered in connection with de Rham cohomology, a foundational tool in differential geometry and topology that assigns to a differentiable manifold a sequence of algebraic invariants derived from differential forms. The theory is named after Georges de Rham, a Swiss mathematician who formulated it in the mid-20th century.

In botany, Rhamnus is a genus of shrubs and small trees in the buckthorn family, Rhamnaceae. Notable species include Rhamnus cathartica, the common buckthorn. Alder buckthorn was traditionally placed in Rhamnus as Rhamnus frangula, but is now usually classified in the separate genus Frangula. The genus is native to Europe, Asia, and Africa, and several species have become invasive in parts of North America.

As a surname or part of a surname, Rham appears infrequently. The most prominent bearer linked to the term is Georges de Rham (1903–1990), a Swiss mathematician whose work on differential geometry is associated with de Rham cohomology. In general usage, Rham may also appear as a component of longer names or in academic references to related mathematical or botanical topics.