 
Summary: IEEE TRANSACTION ON COMPUTER AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS, VOL. 19, NO. 7, JULY 2000 819
though the proposed method is sound, it is not a complete method, i.e.,
there are pairs of equivalent circuits for which it cannot prove equiv
alence. The method can be used as an effective preprocessing step for
a general method such as [10]. It is interesting to note that for some
synthesis steps, the method is complete. This is, e.g., the case for cir
cuits optimized with combinational synthesis techniques, and also for
retimed circuits.
The proposed method assumes that an initial state is designated for
both circuits. This initial state is used in two ways: It acts as a reference
point to allow the detection of antivalent signals, and it is used to calcu
late the initial partition T0 of the set F. The approach of [4] shows that
the assumption of a designated initial state can be weakened. It should
be possible to extend their work such that it also applies to the method
presented in this paper.
ACKNOWLEDGMENT
The author would like to thank W. Kunz and D. Stoffel for providing
the circuits of [25].
REFERENCES
[1] P. Ashar, A. Gupta, and S. Malik, "Using complete1distinguishability
