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Question: How to extract terms that are a product of a commutative part and an operator part form the expression?

Question:How to extract terms that are a product of a commutative part and an operator part form the expression?

Andriy 270
structured physics type operator
November 23 2014
2

Hello.
I am trying to extract the terms that are a product of a commutative part and an operator part from the input expression. That is I am trying to extract a terms like a*A.B where A and B are quantum pperators.

I am trying to do it by creating corresponding structured type:

restart; 
with(Physics); 
Physics[Setup](op = {A, B}, quiet); 

`type/ProdComOp` := `&*`(commutative, specfunc(anything, Physics:-`*`)); 
z0 := u*A.B-A+k*B+B.A.B+g; 
z1 := z0+v*A.B.A;
S1 := indets(z1, ProdComOp);

and all it is Ok. The result is 
But if

z2 := z0-v*A.B.A; 
S2 := indets(z2, ProdComOp);

then
however I expected to receive the same as S1.

How to handle the sign of the commutative part? Thank you.
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