Quick Notation Question

[robousy]

Hey, I'm going through Hawking and Ellis and want to confirm I have understood some notation correctly.

Are the following correct?

V_{(c;d)}=\nabla_c V^d + \nabla_d V^c

and

V_{[c;d]}=\nabla_c V^d - \nabla_d V^c

Also, do these have specific names?

Thanks in advance!!

Richard

[robphy]

Hey, I'm going through Hawking and Ellis and want to confirm I have understood some notation correctly.

Are the following correct?

V_{(c;d)}=\nabla_c V^d + \nabla_d V^c

and

V_{[c;d]}=\nabla_c V^d - \nabla_d V^c

Also, do these have specific names?

Thanks in advance!!

Richard


V_{(c;d)}=\frac{1}{2!} \left( \nabla_d V_c + \nabla_c V_d \right)

and

V_{[c;d]}=\frac{1}{2!}\left( \nabla_d V_c - \nabla_c V_d \right)

The combinatorial factor is a convenient convention.
With it, you can call these the symmetric and antisymmetric parts of V_{c;d}.
You could call the antisymmetric part the "curl" of V_c.


Note that the operation
{(something)}_{;d} is the same as \nabla_d (something)

[robousy]

Ok Rob! Thanks a lot for clarifying that for me. Very much appreciated.

:smile: