sentence1_binary_parse: ( d ( is ( the ( lens thickness ) ) ) )
sentence1_parse: (ROOT (S (NP (SYM d)) (VP (VBZ is) (NP (DT the) (NN lens) (NN thickness)))))
sentence1: d is the lens thickness
sentence2_parse: (ROOT (S (NP (DT A) (JJ concave) (NN lens)) (VP (VBZ is) (NP (NP (JJR thicker)) (PP (IN at) (NP (DT the) (NNS edges)))) (SBAR (IN than) (S (NP (PRP it)) (VP (VBZ is) (PP (IN in) (NP (DT the) (NN middle))))))) (. .)))
sentence2: A concave lens is thicker at the edges than it is in the middle.