Complexity Theoretical Aspects of OFDDs

  • Beate Bollig
  • Martin Löbbing
  • Martin Sauerhoff
  • Ingo Wegener


Experimental results have shown that OFDDs (ordered functional decision diagrams) are a representation of Boolean functions which are sometimes superior to OBDDs (ordered binary decision diagrams). Most of the complexity theoretical problems have been solved for OBDDs. Here some results for OFDDs are proved. It is NP-complete to decide whether a function represented by some OFDD can be represented by an OFDD of size s using another variable ordering. Given an OFDD representation for an incompletely specified function, it is NP-hard to compute an optimal OFDD cover for this function respecting the same variable ordering. The replacement of variables by constants may cause an exponential blow-up of the OFDD size. Finally, it is investigated how a local change of the variable ordering may change the OFDD size. This leads to simulated annealing algorithms to improve variable orderings.


Boolean Function Variable Ordering Simulated Annealing Algorithm Reachable State Binary Decision Diagram 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Beate Bollig
    • 1
  • Martin Löbbing
    • 1
  • Martin Sauerhoff
    • 1
  • Ingo Wegener
    • 1
  1. 1.Department of Computer ScienceUniversity of DortmundDortmundGermany

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