Open Interval from Wolfram Math. World. Wolfram Demonstrations Project Explore thousands of free applications across science, mathematics, engineering, technology, business, art, finance, social sciences, and more. Elementary Topology Gemignani' title='Elementary Topology Gemignani' />Topology, as a welldefined mathematical discipline, originates in the early part of the twentieth century, but some isolated results can be traced back several. The closure of a set S is the set of all points of closure of S, that is, the set S together with all of its limit points. The closure of S is denoted clS, ClS. An open interval is an interval that does not include its end points. Comfar Iii Expert Full Crack here. The open interval xaltxltb is denoted a,b, although the nonstandard notation a,b is. An interval is a connected portion of the real line. If the endpoints a and b are finite and are included, the interval is called closed and is denoted a,b.