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The product of two one- forms, written as defines a linear map which takes two vectors into the reals:

It is therefore a 0/2 tensor. denotes the outer product. It is the formal notation to show how the 0/2 tensor is formed from two one- forms.

Note that this product is non- commutitative since gives a different result [ Assignment 3 ] i.e.

The most general 0/2 tensor is a linear sum of such outer products. So

where are the components of the map f and we have used linearity.

If we take a basis for f as [ 16 components ], then

But

so we have

Under a Lorentz transformation , the components of f become:

A 0/2 tensor is symmetric if

and anti- symmetric if

It follows that any 0/2 tensor can be uniquely decomposed into a symmetric and anti- symmetric part .

with the symmetric and anti- symmetric parts given by

and