@InProceedings{RS89, author = { Ronald L. Rivest and Robert E. Schapire }, title = { Inference of Finite Automata Using Homing Sequences }, pages = { 411--420 }, doi = { 10.1145/73007.73047 }, acm = { 71 }, booktitle = { Proceedings Twenty-First Annual ACM Symposium on Theory of Computation }, publisher = { ACM }, editor = { D. S. Johnson }, date = { 1989 }, OPTyear = { 1989 }, OPTmonth = { May }, eventdate = { 1989-05-15/1989-05-17 }, eventtitle = { STOC '89 }, venue = { Seattle, Washington }, OPTorganization = { ACM }, abstract = { We present new algorithms for inferring an unknown finite-state automaton from its input/output behavior \emph{in the absence of a means of resetting the machine to a start state}. A key technique used is inference of a \emph{homing sequence} for the unknown automaton. \par Our inference procedures experiment with the unknown machine, and from time to time require a teacher to supply counterexamples to incorrect conjectures about the structure of the unknown automaton. In this setting, we describe a learning algorithm which, with probability $1-\delta$, outputs a correct description of the unknown machine in time polynomial in the automaton's size, the length of the longest counterexample, and $\log(1/\delta)$. We present an analogous algorithm which makes use of a diversity-based representation of the finite-state system. \emph{Our algorithms are the first which are provably effective for these problems, in the absence of a ``reset.''} \par We also present probabilistic algorithms for permutation automata which do not require a teacher to supply counterexamples. For inferring a permutation automaton of diversity $D$, we improve the best previous time bound by a roughly a factor of $D^3/\log D$. }, }