# Co-basis

From Encyclopedia of Mathematics

A basis of a dual or adjoint space.

#### Comments

A co-basis is also called a *dual basis*. Often the terminology "dual basis" or "co-basis" of $E^*$ is used to denote a basis $(e_i^*)$ of $E^*$ such that $e_i^*(e_j)=\delta_{ij}$ (the Kronecker delta), where $(e_i)$ is a given basis of $E$. The pair $(e_i),(e_i^*)$ is referred to as a pair of dual bases.

**How to Cite This Entry:**

Co-basis.

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Co-basis&oldid=39419