[
    [["<Sentence>"], ["<NP>", "<VP>"]],
    [["<NP>"],       ["<Det>", "<Noun>"]],
    [["<VP>"],       ["<Verb>", "<NP>"]],
    [["<Det>"],      ["the"]],
    [["<Det>"],      ["a"]],
    [["<Noun>"],     ["dog"]],
    [["<Noun>"],     ["penguin"]],
    [["<Verb>"],     ["sees"]]
]