This is, up to a similarity transformation, the (⁠ 1 / 2 ⁠,0) ⊕ (0, ⁠ 1 / 2 ⁠) Dirac spinor representation of s o ( 3 ; 1 ) . It acts on the 4-component elements (Ψ L, Ψ R) of (V L ⊕ V R), called bispinors, by matrix multiplication. The representation may be obtained in a more general and basis independent way using Clifford algebras. These expressions for bispinors and Weyl spinors all extend by linearity of Lie algebras and representations to all of s o ( 3 ; 1 ) . Expressions for the group representations are obtained by exponentiation.