Polyhedral aspects of score equivalence in Bayesian network structure learning

Full Length Paper Series A

DOI: 10.1007/s10107-016-1087-2

Cite this article as:
Cussens, J., Haws, D. & Studený, M. Math. Program. (2016). doi:10.1007/s10107-016-1087-2


This paper deals with faces and facets of the family-variable polytope and the characteristic-imset polytope, which are special polytopes used in integer linear programming approaches to statistically learn Bayesian network structure. A common form of linear objectives to be maximized in this area leads to the concept of score equivalence (SE), both for linear objectives and for faces of the family-variable polytope. We characterize the linear space of SE objectives and establish a one-to-one correspondence between SE faces of the family-variable polytope, the faces of the characteristic-imset polytope, and standardized supermodular functions. The characterization of SE facets in terms of extremality of the corresponding supermodular function gives an elegant method to verify whether an inequality is SE-facet-defining for the family-variable polytope. We also show that when maximizing an SE objective one can eliminate linear constraints of the family-variable polytope that correspond to non-SE facets. However, we show that solely considering SE facets is not enough as a counter-example shows; one has to consider the linear inequality constraints that correspond to facets of the characteristic-imset polytope despite the fact that they may not define facets in the family-variable mode.


Family-variable polytope Characteristic-imset polytope Score equivalent face/facet Supermodular set function 

Mathematics Subject Classification

52B12 90C27 68Q32 

Copyright information

© Springer-Verlag Berlin Heidelberg and Mathematical Optimization Society 2016

Authors and Affiliations

  1. 1.Department of Computer Science and York Centre for Complex Systems AnalysisUniversity of YorkDeramore LaneUK
  2. 2.Thomas J. Watson Research CenterYorktown HeightsUSA
  3. 3.Institute of Information Theory and Automation of the CASPragueCzech Republic