1. Weak Cost Register Automata are Still Powerful.
- Author
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Almagor, Shaull, Cadilhac, Michaël, Mazowiecki, Filip, and Pérez, Guillermo A.
- Subjects
MACHINE theory ,COST ,MATHEMATICAL equivalence ,LOGICAL prediction ,CLINICAL trial registries - Abstract
We consider one of the weakest variants of cost register automata over a tropical semiring, namely copyless cost register automata over ℕ with updates using min and increments. We show that this model can simulate, in some sense, the runs of counter machines with zero-tests. We deduce that a number of problems pertaining to that model are undecidable, namely equivalence, upperboundedness, and semilinearity. In particular, the undecidability of equivalence disproves a conjecture of Alur et al. from 2012. To emphasize how weak these machines are, we also show that they can be expressed as a restricted form of linearly-ambiguous weighted automata. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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