greatest lower bound
GLB
infimum
Meet

    (glb, meet, infimum) The greatest lower bound of two
   elements, a and b is an element c such that c <= a and c <= b
   and if there is any other lower bound c' then c' <= c.

   The greatest lower bound of a set S is the greatest element b
   such that for all s in S, b <= s.  The glb of mutually
   comparable elements is their minimum but in the presence of
   incomparable elements, if the glb exists, it will be some
   other element less than all of them.

   glb is the dual to least upper bound.

   (In LaTeX "<=" is written as \sqsubseteq, the glb of two
   elements a and b is written as a \sqcap b and the glb of set
   S as \bigsqcap S).

   (1995-02-03)