Adjective
non-empty (not comparable)
(set theory) Of a set, containing at least one element; not the empty set.
An example of an NP-complete problem is the subset sum problem : given a finite set of integers, is there a non-empty subset that sums to zero? Source: Internet
Also: if a non-empty complete metric space is the countable union of closed sets, then one of these closed sets has non-empty interior. Source: Internet
A serial relation can be equivalently characterized as every element having a non-empty successor neighborhood (see the previous section for the definition of this notion). Source: Internet
A non-compact surface M has a non-empty space of ends E(M), which informally speaking describes the ways that the surface "goes off to infinity". Source: Internet
An important property of the natural numbers is that they are well-ordered : every non-empty set of natural numbers has a least element. Source: Internet
A set X is well-ordered by a strict total order if every non-empty subset of X has a least element under the ordering. Source: Internet