What is the addition of subspaces in linear algebra?

[moonbounce7]

What exactly is the "addition of subspaces?" It is obviously not the same as the "union of subspaces," since the union of subspaces A and B in V is a subspace of V only if A is contained in B (or B is contained in A).

 

[NoMoreExams]

You should probably only ask the same question in one place.

 

[Fredrik]

It probably refers to the direct sum of two vector spaces. Link.

 

[NoMoreExams]

This is exactly why I think starting multiple threads with the same question is bad: https://www.physicsforums.com/showthread.php?t=287527