Let e1,e2,…,en∈V be a basis of vector space V, and let e1,…,en∈V∗ be a basis of dual space V∗. Now if eˉi=Cikek is another basis of V, then there is an induced basis eˉi=(C−1)kiek for dual space V∗.
Proof
By Kronecker-delta 1=δii
1=δii=eˉieˉi=Cikekeˉi
can see that if eˉi=ek(C−1)ki then the equality is hold. We can use Penrose notation to show the idea.