cool animation

[Bachelier]

"is there a difference between intersect and poking a hole in the surface?"



Nonius (and others) are the topologists here.



if you poke a hole in something, there is empty space there.



If two lines intersect, at that singularity, both lines have the same coordinate and both lines pass through that coordinate.



Same with planes



Same with....N dimensions.



math guys, I'm making a hash of this. Correct and enlighten us.

[chiral3]

yes, there is a difference. Mapping the points to points on the other side is fine. Putting a hole in the surface would change the genus. We can't have a sphere be the same as a torus.