/*
  The function Fabr changes letters 'A' to 'B' in a string and appends 'B' to the result.
  If the usual order of generalization is applied, the generalization produces a parameter, which is always empty.
  Using word equations during generalization as rewrite rules, we avoid the redundant parameters.
*/

/***********************************************/
/*           the input program                 */
/***********************************************/
$ENTRY Go {
  e.X = <Fabr (e.X 'A') ()>;
}

Fabr {
  (e.Left 'A') (e.Right) = <Fabr (e.Left) ('B' e.Right)>;
  (e.Left s.X) (e.Right) = <Fabr (e.Left) (s.X e.Right)>;
  () (e.Right) = e.Right;
}

/***********************************************/
/*          the residual program               */
/***********************************************/

/*
$ENTRY Go {
 e.x1 =  <Fabr_123_0 (e.x1) ()>;
}


Fabr_123_0 {
 (e.x1 'A') (e.x2) =  <Fabr_123_0 (e.x1) ('B' e.x2)>;
 (e.x1 s.z1) (e.x2) =  <Fabr_123_0 (e.x1) (s.z1 e.x2)>;
 () (e.x1) =  e.x1 'B';
}

*/