Peirce decomposition
In algebra, a Peirce decomposition /ˈpɜːrs/ is a decomposition of an algebra as a sum of eigenspaces of commuting idempotent elements. The Peirce decomposition for associative algebras was introduced by BenjaminPeirce (1870,proposition 41, page 13). A similar but more complicated Peirce decomposition for Jordan algebras was introduced by Albert (1947).