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Comparison with the FSM library

We also provide the results for AT&T's FSM library again. FSM is designed to treat weighted automata for very general weight sets. The initial implementation of the library consisted of an on-the-fly computation of the epsilon-closures combined with determinisation. This was abandoned for two reasons: it could not be generalised to the case of general weight sets, and it was not outputting the intermediate epsilon-removed machine (which might be of interest in itself). In the current version $\epsilon $-moves must be removed before determinisation is possible. This mechanism thus is comparable to our per graph variant. Apparently, FSM employs an algorithm equivalent to our per graphs,a. The resulting determinised machines are generally larger than the machines produced by our integrated variants and the variants which incorporate $\epsilon $-moves on the target side of transitions. The timings below are obtained for the pipe

\begin{displaymath}
\mbox{\tt fsmrmepsilon \vert fsmdeterminize }
\end{displaymath}

This is somewhat unfair since this includes the time to write and read the intermediate machine. Even so, it is interesting to note that the FSM library is a constant factor faster than our per graphs,a; for larger numbers of jumps the per state and per subset variants consistently beat the FSM library.


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Next: Experiment: Automata generated by Up: Experiments Previous: Random automata.

2000-07-10