Drag the points below they are shown as dots so you can see them but a point really has no size at all Points usually have a name often a letter like A or B etc. 2010 Mathematics Subject Classification. Or drag the point K.
The set Int A Ac 18 is called the interior of A.
A point that is in the interior of S is an interior point of S. A point that lies in the interior of a line segment divides the segment into 2 segments. Interior closure and boundary We wish to develop some basic geometric concepts in metric spaces which make precise certain intuitive ideas centered on the themes of interior and boundary of a subset of a metric space. Basic Point-Set Topology 3 means that fx is not in OOn the other hand x0 was in f 1O so fx 0 is in OSince O was assumed to be open there is an interval cd about fx0 that is contained in OThe points fx that are not in O are therefore not in cd so they remain at least a fixed positive distance from fx0To summarize.