catflap.org Online Dictionary Query

  SET
       
          1.  Secure Electronic Transaction.
       
          2.  Single Electron Tunneling.
       
          3.  Standard d'Echange et de Transfert.
       
          (1999-03-26)
       
       

  set
       
          A collection of objects, known as the elements of the set,
          specified in such a way that we can tell in principle whether
          or not a given object belongs to it.  E.g. the set of all prime
          numbers, the set of zeros of the cosine function.
       
          For each set there is a predicate (or property) which is
          true for (posessed by) exectly those objects which are
          elements of the set.  The predicate may be defined by the set
          or vice versa.  Order and repetition of elements within the
          set are irrelevant so, for example, 1, 2, 3 = 3, 2, 1 =
          1, 3, 1, 2, 2.
       
          Some common set of numbers are given the following names:
       
          N = the natural numbers 0, 1, 2, ...
       
          Z = the integers ..., -2, -1, 0, 1, 2, ...
       
          Q = the rational numbers p/q where p, q are in Z and q /= 0.
       
          R = the real numbers
       
          C = the complex numbers.
       
          The empty set is the set with no elements.  The intersection
          of two sets X and Y is the set containing all the elements x
          such that x is in X and x is in Y.  The union of two sets is
          the set containing all the elements x such that x is in X or x
          is in Y.
       
          See also set complement.
       
          (1995-01-24)