sel s N cons X sel N XS from X cons X sel 0 cons X X minus X 0 0 minus s X s Y minus X Y quot 0 s Y 0 quot s X s Y s quot minus X Y s Y zWquot XS nil nil zWquot nil XS nil zWquot cons X cons Y cons quot X Y sel 2 s 1 cons 1 from 1 0 0 minus 2 quot 2 zWquot 2 nil 0 FULL ./TRS/TRCSR/Ex4_7_37_Bor03_L.trs