# Nonstochastic languages as projections of 2-tape quasideterministic languages

Contributed Papers Logic - Semantics - Automata

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## Abstract

A language *L* ^{ (n) } of *n*-tuples of words which is recognized by a *n*-tape rational finite-probabilistic automaton with probability 1-*ε*, for arbitrary *ε* > 0, is called quasideterministic. It is proved in [Fr 81], that each rational stochastic language is a projection of a quasideterministic language *L* ^{ (n) } of *n*-tuples of words. Had projections of quasideterministic languages on one tape always been rational stochastic languages, we would have a good characterization of the class of the rational stochastic languages. However we prove the opposite in this paper. A two-tape quasideterministic language exists, the projection of which on the first tape is a nonstochastic language.

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## References

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