Declare a Commutation Relationship in FeynCalc

[ShadowMeson]

Homework Statement

I am a rookie to the QFT extension in Mathematica called FeynCalc, and tried to use that into solving some quiz. Soon I met a problem upon some condition presented in a problem which declares an relation of two same tensor with different indices results in some value when commuted. I don't know how to express such relationship nor how intelligent the program is in dealing with that.

Homework Equations

Thai problem is Peskin&Schroeder 3.1.

The Attempt at a Solution

Searched the document and examples, no practical suggestions found yet.

 

[ShadowMeson]

Got the response from my kind of tutor that such operation ain't the focus of FeynCalc and I shall focus on other tools.