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On shuffle products, acyclic automata and piecewise-testable languages (1810.02953v2)
Published 6 Oct 2018 in cs.FL
Abstract: We show that the shuffle $L \unicode{x29E2} F$ of a piecewise-testable language $L$ and a finite language $F$ is piecewise-testable. The proof relies on a classic but little-used automata-theoretic characterization of piecewise-testable languages. We also discuss some mild generalizations of the main result, and provide bounds on the piecewise complexity of $L \unicode{x29E2} F$.