Assuming we have access to a scoring function Score(•, •) that tells how well a dependency tree fits the syntactic structure of a sentence, the goal of dependency parsing is to find the treeŷ such that: The size of T x grows exponentially with the length of x, |T x | = |x| |x|−2 , making an exhaustive search for the best tree impractical in most cases.
in practice, some simplifying assumptions are made.