The even subalgebra Cℓ 2,0 ( R ), spanned by even-graded basis elements of Cℓ 2,0 ( R ), determines the space of spinors via its representations. It is made up of real linear combinations of 1 and σ 1 σ 2. As a real algebra, Cℓ 2,0 ( R ) is isomorphic to the field of complex numbers C . As a result, it admits a conjugation operation (analogous to complex conjugation), sometimes called the reverse of a Clifford element, defined by ( a + b σ σ 1 σ σ 2 ) ∗ ∗ = a + b σ σ 2 σ σ 1 . which, by the Clifford relations, can be written ( a + b σ σ 1 σ σ 2 ) ∗ ∗ = a + b σ σ 2 σ σ 1 = a − − b σ σ 1 σ σ 2 .