Ray is a geometric concept that refers to each of the two portions where the right is divided by any of its points. It is important to clarify that the correct term is half-right (with a hyphen) and not not demidroite.
However, the ray is the part of a line that is formed by all the points that lie on one side of a fixed point: This means that XLine has a first point (origin), but it extends to infinity. The right, on the other hand, has no start or end point.
In other words, the right is an infinite succession of points. The Ray has a point of origin from which constantly follow points. The segment, in turn, depends on the intersection of the set of two integration points (there is a beginning and an end).
The closed line designation is not more wrong, since it includes the point of origin unless it extends to infinity, to the image of the ray.
Concerning the bijection between a right and real, we can say that positive real numbers correspond to one of the surface while the negative real numbers correspond to the other. Zero, for its part, is the border (origin) of the two rays.
To understand what XLine, simply imagine a rule that starts with the digit 0 and extends in a natural order to infinity (0, 1, 2, 3, 4, 5, etc.).