  
  [1XC A graphical interface[0X
  
  Here we describe a Tcl/Tk interface to specify numerical semigroups.
  
  
  [1XC.1 Graphical interface[0X
  
  [1XC.1-1 XNumericalSemigroup[0m
  
  [2X> XNumericalSemigroup( [0X[3X[s][0X[2X ) _______________________________________[0Xfunction
  
  This  function  pops  up  a  Tcl/Tk window which allows the specification of
  numerical semigroups. The optional argument [3Xs[0m is a numerical semigroup whose
  definition becomes displayed in the graphical interface.
  
  The  interface is very simple, it allows to specify a numerical semigroup by
  its  generators  or  a  (proportionally)  modular numerical semigroup by its
  (proportionally)  modular condition. The [5XGAP[0m variable by which the semigroup
  will be known must also be specified.
  
  The  interface  also allows to apply some functions to the semigroup, namely
  [2XAperyListOfNumericalSemigroupWRTElement[0m                             ([14X3.1-5[0m),
  [2XDrawAperyListOfNumericalSemigroup[0m ([14X3.1-6[0m), [2XSmallElementsOfNumericalSemigroup[0m
  ([14X3.1-3[0m),                  [2XGapsOfNumericalSemigroup[0m                  ([14X3.3-1[0m),
  [2XFrobeniusNumberOfNumericalSemigroup[0m                ([14X3.2-1[0m)               and
  [2XMinimalPresentationOfNumericalSemigroup[0m   ([14X4.1-2[0m).   Finally,   it  is  also
  possible to add functions to this list and remove them.
  
  [4X---------------------------  Example  ----------------------------[0X
    [4Xgap> s:=RandomNumericalSemigroup(3,9);[0X
    [4X<Numerical semigroup with 3 generators>[0X
    [4Xgap> XNumericalSemigroup(s);[0X
  [4X------------------------------------------------------------------[0X
  
  This would pop up the following window:
  
