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MFCS
1998
Springer

Blockwise Variable Orderings for Shared BDDs

13 years 7 months ago
Blockwise Variable Orderings for Shared BDDs
In this paper we consider the problem of characterizing optimal variable orderings for shared OBDDs of two Boolean functions fi = gi i hi, i = 1, 2, where i is an operator from the Base B 2 and gi (resp. hi) depends only on x-variables (resp. y-variables). Tree-like circuits provide an example for such functions. In the special case f1 = f2, Sauerhoff, Wegener and Werchner [6] proved that there is some optimal ordering where all x-variables are tested before all y-variables or vice versa. We show that this is also true for arbitrary f1, f2 provided that 1 = and 2 = , and for shared OBDDs with complemented edges and arbitrary f1, f2 provided that 1 = and 2 = . For all other combinations of 1 und 2 we give counterexamples.
Harry Preuß, Anand Srivastav
Added 06 Aug 2010
Updated 06 Aug 2010
Type Conference
Year 1998
Where MFCS
Authors Harry Preuß, Anand Srivastav
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