On the Complexity of the Evaluation of Transient Extensions of Boolean Functions

Janusz Brzozowski
(University of Waterloo)
Baiyu Li
(University of Waterloo)
Yuli Ye
(University of Toronto)

Transient algebra is a multi-valued algebra for hazard detection in gate circuits. Sequences of alternating 0's and 1's, called transients, represent signal values, and gates are modeled by extensions of boolean functions to transients. Formulas for computing the output transient of a gate from the input transients are known for NOT, AND, OR and XOR gates and their complements, but, in general, even the problem of deciding whether the length of the output transient exceeds a given bound is NP-complete. We propose a method of evaluating extensions of general boolean functions. We introduce and study a class of functions with the following property: Instead of evaluating an extension of a boolean function on a given set of transients, it is possible to get the same value by using transients derived from the given ones, but having length at most 3. We prove that all functions of three variables, as well as certain other functions, have this property, and can be efficiently evaluated.

In Ian McQuillan and Giovanni Pighizzini: Proceedings Twelfth Annual Workshop on Descriptional Complexity of Formal Systems (DCFS 2010), Saskatoon, Canada, 8-10th August 2010, Electronic Proceedings in Theoretical Computer Science 31, pp. 27–37.
Published: 7th August 2010.

ArXived at: http://dx.doi.org/10.4204/EPTCS.31.5 bibtex PDF

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