Lines in space. 2. The line formulation

In part 1, we were talking about points, planes, and lines in 3D, more particularly in projective 3-space. The idea is to find algebraic expressions for the various geometric relationships between these objects. We were just on the verge of discovering what would be a good algebraic formulation for lines in projective 3D space. My goal here is to update my original paper to see how the results look using tensor diagram notation. I start by reviewing what we did last time, but will say some things a bit differently. You might pick up more insight from this different viewpoint.