have strip-mined the monty formula mercilessly since 1997 . 
(ROOT (S (VP (VB have) (VP (NN strip) (HYPH -) (VBN mined) (NP (DT the) (NN monty) (NN formula)) (ADVP (RB mercilessly)) (PP (IN since) (NP (CD 1997))))) (. .)))
(ROOT (S (VP (VB ) (VP (NN ) (HYPH ) (VBN ) (NP (DT ) (NN ) (NN )) (ADVP (RB )) (PP (IN ) (NP (CD ))))) (. )))