DEFINITION MODULE EClasses;

   (* EXPORT QUALIFIED EClass, EClazz; *)

   FROM NRIVect IMPORT IVector; 

   TYPE EquivFunction = PROCEDURE (INTEGER, INTEGER): BOOLEAN;

   PROCEDURE EClass(NF, LISTA, LISTAB: IVector); 
   (*
     Given m equivalences between pairs of n individual elements
     in the form of the input arrays LISTA[0, m-1] and LISTB[0, m-1], this routine
     returns in NF[0, n-1] the number of the equivalence class of each of the
     n elements, integers between 1 and n (not all such integers used).
   *)

   PROCEDURE EClazz(NF: IVector; equiv: EquivFunction); 
   (*
     Given a user-supplied boolean function equiv that tells
     whether a pair of elements, each in the range 1...n, are related,
     return in NF[0, n-1] equivalence class numbers for each element.
   *)

END EClasses.