( ( on ( the ( other hand ) ) ) ( , ( ( ( a solution ) ( to ( a ( ( ( more and ) ( more complex ) ) problem ) ) ) ) ( ( was ( becoming ( increasingly elusive ) ) ) . ) ) ) )
(ROOT (S (PP (IN on) (NP (DT the) (JJ other) (NN hand))) (, ,) (NP (NP (DT a) (NN solution)) (PP (TO to) (NP (DT a) (ADJP (ADJP (JJR more)) (CC and) (ADJP (RBR more) (JJ complex))) (NN problem)))) (VP (VBD was) (VP (VBG becoming) (ADJP (RB increasingly) (JJ elusive)))) (. .)))
on the other hand, a solution to a more and more complex problem was becoming increasingly elusive.
(ROOT (S (PP (IN As) (NP (NN ph) (NNS increases))) (, ,) (NP (DT a) (NN solution)) (VP (VBZ becomes) (ADJP (RBR more) (JJ basic))) (. .)))