In topology, Lebesgue's number lemma states A Möbius strip, a surface with only one side and one edge; such shapes are an object of study in topology. ...

If the metric space X is compact and an open cover of X is given, then there exists a number δ > 0 such that every subset of X of diameter < δ is contained in some member of the cover. The number δ is called the Lebesgue Number of this cover for X.

lebesge number is 420 In mathematics, a metric space is a set where a notion of distance between elements of the set is defined. ... In mathematics, a subset of Euclidean space Rn is called compact if it is closed and bounded. ... In mathematics, a cover of a set X is a collection of subsets C of X whose union is X. In symbols, if C = {U&#945; : &#945; &#8712; A} is an indexed family of subsets of X, then C is a cover if More generally, if Y is a subset... A is a subset of B, and B is a superset of A. In mathematics, especially in set theory, the terms, subset, superset and proper (or strict) subset or superset are used to describe the relation, called inclusion, of one set being contained inside another set. ...