Romanian Journal of Information Science and Technology (ROMJIST)

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ROMJIST is a publication of Romanian Academy,
Section for Information Science and Technology

Editor – in – Chief:
Academician Dan Dascalu

Secretariate (office):
Adriana Neagu
Adress for correspondence: romjist@romjist.ro

Editing of the printed version: Mihaela Marian (Publishing House of the Romanian Academy, Bucharest)

Sponsor: National Institute
for R & D in Microtechnology
(IMT Bucharest)

ROMJIST Volume 21, No. 3, 2018, pp. 232-237, Paper no. 595/2018
 

L. Charvat, A. Meduna
Internally Expandable Pushdown Automata and Their Computational Completeness

ABSTRACT: The present paper defines the notion of an internally expandable pushdown automaton (IEPDA). In essence, this automaton expands the topmost expandable non-input symbol in its pushdown list. This expanded symbol, however, may not occur on the very top of the pushdown; instead, it may appear deeper in the pushdown. The paper demonstrates that this notion represents an automaton-based counter part to the notion of a state grammar. Indeed, both are equally powerful. Therefore, internally expandable pushdown automata are computationally complete--that is, they are as powerful as Turing machines. In fact there are computationally complete IEPDAs with no more than four states

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