Using the grammar below, my text says that the string "the girl touches the boy with the flower" can be leftmost derived in two ways making the grammar ambiguous. When I try to find the second derivation, I fail. I really do not see how a second derivation is possible since getting the terminals follows a standard one way pattern: all go from a phrase nonterminal to a couple non-terminals that go to terminals to the terminals.
Grammar
⟨SENTENCE⟩→⟨NOUN-PHRASE⟩⟨VERB-PHRASE⟩
⟨NOUN-PHRASE⟩→⟨CMPLX-NOUN⟩ | ⟨CMPLX-NOUN⟩⟨PREP-PHRASE⟩
⟨VERB-PHRASE⟩→⟨CMPLX-VERB⟩ | ⟨CMPLX-VERB⟩⟨PREP-PHRASE⟩
⟨PREP-PHRASE⟩→⟨PREP⟩⟨CMPLX-NOUN⟩
⟨CMPLX-NOUN⟩→⟨ARTICLE⟩⟨NOUN⟩
⟨CMPLX-VERB⟩→⟨VERB⟩ | ⟨VERB⟩⟨NOUN-PHRASE⟩
⟨ARTICLE⟩ → a | the
⟨NOUN⟩ → boy | girl | flower
⟨VERB⟩ → touches | likes | sees
⟨PREP⟩ → with
Below is how I got my first leftmost derivation.
Sentence,
Noun-phrase Verb-phrase,
Cmplx-noun Verb-phrase,
Article Noun Verb-phrase,
the Noun Verb-phrase,
the girl Verb-phrase,
the girl Complx-Verb,
the girl Verb Noun-phrase,
the girl touches Noun-phrase,
the girl touches Cmplx-noun Prep-phrase,
the girl touches Article Noun Prep-phrase,
the girl touches the Noun Prep-phrase,
the girl touches the boy Prep-phrase,
the girl touches the boy Prep Cmplx-noun,
the girl touches the boy with Cmplx-noun,
the girl touches the boy with Article Noun,
the girl touches the boy with the Noun,
the girl touches the boy with the flower
At
the girl Verb-phrase
Use
⟨VERB-PHRASE⟩→⟨CMPLX-VERB⟩⟨PREP-PHRASE⟩
Then <PREP-PHRASE> will generate "with the flower".