I don't agree with the notion that lines and straight lines mean the same thing, Sam, mainly because we're then at a loss to account for curves.    Geodesic      http://mathworld.wolfram.com/Geodesic.html     A geodesic is a locally length-minimizing curve. Equivalently, it    is a path that a particle which is not accelerating would follow.    In the plane, the geodesics are straight lines. On the sphere, the    geodesics are great circles  (like the equator). The geodesics in    a space depend on the Riemannian metric, which affects the notions    of distance and acceleration .

[...] What is your background in mathematics, Lester? You have asked: what is the empty set . The empty set was my only source of amusement in my proofs class. - Ukryj cytowany tekst -- Poka? cytowany tekst - Bob Kolker

If the point is defined by the intersection what happens to the point and what defines the point when the lines don't intersect? On the other hand if the point is not defined by the intersection of lines how can one assume the line is made up of things which aren't defined? hahahahaha you are poor philosopher. Obviously. That's why I became a mathematician. You did? Gosh, congratulations! Brian Chandler http://imaginatorium.org (just wanting to be part of this golden thread, this irridescent braid, this)