title: StanfordNLP, CoreNLP, spaCy - different dependency graphs
body: <p>I'm trying to use simple rules/patterns defined over a dependency graph to extract very basic informations from sentences (e.g., triples such as subject->predicate->object). I started using <a href="https://stanfordnlp.github.io/stanfordnlp/pipeline.html" rel="nofollow noreferrer">StanfordNLP</a> since it was easy to set up and utlizes the GPU for better performance. However, I've noticed that for some sentences, the resulting dependency graph looked not as I would have expected -- I'm no expert though. I therefore tried two other solutions: <a href="https://spacy.io/usage/linguistic-features" rel="nofollow noreferrer">spaCy</a> and <a href="https://stanfordnlp.github.io/CoreNLP/" rel="nofollow noreferrer">Stanford CoreNLP</a> (I understand that these are maintained by different groups?)</p>
  
  <p>For the example sentence <em>"Tom made Sam believe that Alice has cancer."</em> I've printed the dependencies for all three approaches. CoreNLP and spaCy yield the same dependencies, and they are different from the ones of StanfordNLP. Hence, I'm inclined to swich to CoreNLP and spaCy (another advantage would be that they come with NER out of the box).</p>
  
  <p>Does anyone have some more experience or feedback that would help where to go from here? I don't expect that CoreNLP and spaCy will always yield in the same dependency graphs, but in the example sentence, considering <code>Sam</code> as <code>obj</code> as StandfordNLP is doing compared to being <code>nsubj</code> (CoreNLP, spaCy) seems to be a significant difference</p>
  
  <pre><code>Format:
  token   dependency_tag   parent_token
  
  StanfordNLP
  Tom     nsubj   made
  made    ROOT    ROOT
  Sam     obj     made
  believe ccomp   made
  that    mark    has
  Alice   nsubj   has
  has     ccomp   believe
  cancer  obj     has
  .       punct   made
  
  CoreNLP
  Tom     nsubj   made
  made    ROOT    ROOT
  Sam     nsubj   believe
  believe ccomp   made
  that    mark    has
  Alice   nsubj   has
  has     ccomp   believe
  cancer  dobj    has
  .       punct   made
  
  spaCy
  Tom     nsubj   made
  made    ROOT    ROOT
  Sam     nsubj   believe
  believe ccomp   made
  that    mark    has
  Alice   nsubj   has
  has     ccomp   believe
  cancer  dobj    has
  .       punct   made
  </code></pre>