<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>27</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Alexandra Silva</style></author><author><style face="normal" font="default" size="100%">SergeyGoncharov</style></author><author><style face="normal" font="default" size="100%">Stefan Milius</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Towards a Coalgebraic Chomsky Hierarchy</style></title></titles><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">December</style></date></pub-dates></dates><publisher><style face="normal" font="default" size="100%">HASLab/INESC TEC &amp; University of Minho</style></publisher><pub-location><style face="normal" font="default" size="100%">Braga, Portugal</style></pub-location><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The Chomsky hierarchy plays a prominent role in the foundations of the theoretical computer science relating classes of formal languages of primary importance. In this paper we use recent developments on coalgebraic and monad-based semantics to obtain a generic notion of a T-automaton, where T is a monad, which allows the uniform study of various notions of machines (e.g. finite state machines, multi-stack machines, Turing machines, valence automata, weighted automata). We use the generalized powerset construction to define a generic (trace) semantics for T-automata, and we show by numerous examples that it correctly instantiates for the known classes of machines/languages captured by the Chomsky hierarchy. Moreover, our approach provides new generic techniques for proving expressivity bounds of various machine-based models.&lt;/p&gt;
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