COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002
C00004 ENDMK
C⊗;


(DE RESIDUE (X Y) 
       (COND ((EQ X Y) T)
	     ((AND (ATOM X) (ATOM Y)) NIL)
	     ((ATOM X)
	      ((LAMBDA (W) 
		       (COND ((EQ X (CAR W)) (CONS 'R (CDR W)))
			     (T NIL)))
	       (GOPHER Y)))
	     ((ATOM Y)
	      ((LAMBDA (W) 
		       (COND ((EQ Y (CAR W)) (CONS 'L (CDR W)))
			     (T NIL)))
	       (GOPHER X)))
	     (T ((LAMBDA (W) 
			 (COND ((NULL W) NIL)
			       ((EQ W T) (RESIDUE (CDR X) (CDR Y)))
			       ((EQ (CAR W) 'L)
				(RESIDUE (CONS (CDR W) (CDR X))
					 (CDR Y)))
			       (T (RESIDUE (CDR X)
					   (CONS (CDR W) (CDR Y))))))
		 (RESIDUE (CAR X) (CAR Y)))))) 

(DE GOPHER (U) 
       (COND ((ATOM (CAR U)) U)
	     (T (GOPHER (CONS (CAAR U) (CONS (CDAR U) (CDR U))))))) 


(DE SAMEFRINGE (X Y) (EQ (RESIDUE X Y) T))