In "OpenGIS® Implementation Standard for Geographic information - Simple feature access - Part 1: Common architecture" is stated:
A Curve is a 1-dimensional geometric object that is the homeomorphic image of a real, closed, interval in the coordinate space.
Looking at definition of homeomorphism:
A homeomorphism, also called a continuous transformation, is an equivalence relation and one-to-one correspondence between points in two geometric figures or topological spaces that is continuous in both directions
and taking as an example a LinearRing that is a LineString (which is a Curve with linear interpolations between points) which has a common point of the start (s) of the starting line segment and the end (e) of the ending line segment I cannot understand or prove to myself that a LinerRing is a homeomorphic image of an interval.
Any help is highly appreciated.
UPDATE:
I have read the definitions more carefully (Wikipedia) and they have clarified the situation.
If it is defined so then I may conclude: the curve is only 1-dimensional when there is a homeomorphism from interval to the topological space, a ring cannot be mapped in this way and therefore is not 1-dimensional. Moreover, not every curve is 1-dimensional.
The OpenGIS document does not define the closed curve (or a ring) explicitly and therefore the text where it is written is confusing. My confusion was mainly connected with the following logical consequence: 1) A curve is a homeomorphism from interval to a coordinate space therefore 2) the curve is 1-dimensional. 3) A ring is a curve with starting and ending point of an interval mapped to the same point (closed curve) and 4) since a ring is a simple (there is not intersections) and closed curve then it is 1-dimensional. In fact, it is nowhere stated in the document that a closed curve is 1-dimensional. I understood that when I have explicitly found definition of the closed curve.
Typically, a curve is one-dimensional because you only need a single number to describe a point's position on the curve: distance from an end point or chosen origin.
Describing the space the curve occupies in a larger world is another matter completely :) but you could place a point on a straight number line, a point on the curve, and for every unit of movement of one point, move the other point a corresponding distance.