11. Its universe and least element are symbolized by " U " and \ emptyset, respectively. 12. A linear order where every nonempty subset has a least element is called a well-order. 13. Its universe and least element are symbolized by " U " and \ varnothing, respectively. 14. More generally, Chomp can be played on any partially ordered set with a least element . 15. A player loses by taking the least element . 16. A join-semilattice is "'bounded "'if it has a least element , the join of the empty set. 17. Every non-empty well-ordered set has a least element . 18. The notation 0 is frequently found for the least element , even when no numbers are concerned. 19. However, if there is a least element , then it is the only minimal element of the order. 20. In particular, it contains a least element and a greatest element ( also denoted " universe " ).
