@techreport{Shant:TR2010-0009,
  AUTHOR = {Shant Karakashian and Berthe Y. Choueiry},
  TITLE = {{Tree-Based Algorithms for Computing $k$-Combinations and $k$-Compositions}}, 
  YEAR = 2010,
  TYPE = {Technical Report},
  NUMBER = {TR-UNL-CSE-2010-0009},
  INSTITUTION = {Constraint Systems Laboratory, University of Nebraska-Lincoln},
  ADDRESS = {Lincoln, NE},
  KEYWORDS = {}}