MBOT Moses Translation System

Type Tool
Title MBOT Moses Translation System
Author Fabienne Braune, Nina Seemann, Daniel Quernheim, Andreas Maletti


The MBOT Moses Translation System is a statistical machine translation system based on multi bottom-up tree transducers (MBOT). An MBOT is a synchronous grammar that models discontinuities by allowing a sequence of target tree fragments on the right hand side of its rules. A formal description can be found in [1].

We implemented various rule extractions to test the power of MBOT in different settings:  

  • minimal tree-to-tree rules as described in [1] and [2]
  • non-minimal string-to-tree rules as described in [3]
  • non-minimal tree-to-tree and string-to-string rules as described in [4]
  • non-minimal tree-to-string rules

Furthermore, we developed a method that allows one to transform dependency parse trees into constituent-like tree representations. The method and evaluation is given in [5]. The dependency parser we used yielded sometimes non-projective dependency parse trees. Those need to be converted into projective ones. If you are interested in this code, please contact Anders Björkelund [Link].


  1. Andreas Maletti. How to Train your Multi Bottom-up Tree Transducer. Proc. 49th ACL, 2011. 
  2. Fabienne Braune, Nina Seemann, Daniel Quernheim & Andreas Maletti. Shallow Local Multi Bottom-up Tree Transducers in Statistical Machine Translation. Proc. 51st ACL., 2013.
  3. Nina Seemann, Fabienne Braune & Andreas Maletti. String-To-Tree Multi Bottom-up Tree Transducers. Proc. 53rd ACL,  2015.
  4. Nina Seemann, Fabienne Braune & Andreas Maletti. A Systematic Evaluation of MBOT in Statistical Machine Translation. Proc. MT Summit XV, 2015.
  5. Nina Seemann & Andreas Maletti. Discontinuous Statistical Machine Translation with Target-Side Dependency Syntax. Proc. 10th WMT,  2015.


  • Download the latest version of the decoder from git:
       git clone -b mbotTestedDecoder git://
  • minimal tree-to-tree: Code for rule extraction, lexical scoring, etc. Instructions on training and tuning.  [download]
  • non-minimal tree-to-tree, string-to-tree, tree-to-string, and string-to-string: Instructions on preprocessing, training and tuning. [download]
  • Instructions and code for transforming dependency parse trees. [download]