# Unexpected behavior of combine()

Hi,

When I apply the command combine() on

$( \Gamma ^ { a } ) _ { \beta } { } ^ { \gamma } ( \Gamma _ { c d } ) _ { \gamma }{ }^{ \alpha }$,

I get

$( \Gamma _ {c d} \Gamma ^ {a} ) ^ { \alpha } { } _ { \beta }$

while expecting

$( \Gamma ^ {a} \Gamma _ { c d } ) _ { \beta }{ } ^ { \alpha }$.

Am i doing something wrong?
(In case not rendering tex, i added image )

In addition, Is there any way to tell such structures to Cadabra;

$A _ {a} B ^ {a} = - A ^ {a} B _ {a}$.

Since our metric is antisymmetric, the shape of the contraction matters.

Thanks in advance :)