The 27 Lines
By a result of Cayley and Salmon, every nondegenerate cubic surface has exactly 27 lines.
The picture above shows the 27 lines of the surface.
For the sake of clarity, the surface has been removed from the picture.
The coloring of the lines will be explained below.
For now, it suffices to say that there are six red lines, six blue lines and 15 yellow lines.
The six red lines and the six blue lines form a Schläfli double six.
File translated from
TEX
by
TTH,
version 4.08.
On 4 Jun 2017, 11:23.