### Abstract

Two ways of introducing alternation for context-free grammars and pushdown automata are compared. One is the usual way which combines "states" with alternation [1], [4], [7], and the other is the way used in [6] to define the alternating context-free grammar, i.e., alternation is governed by the variables of the grammar. In this paper the latter way is taken over to define a new type of alternating pushdown automaton by combining the "pushdown symbols" of the pushdown automaton with alternation. We have derived a characterization of the original alternating context-free grammars in terms of such a new type of alternating pushdown automaton without states. It is also shown that, if (non-alternating) states are introduced as an additional feature for this type of pushdown automaton, then the resulting alternating pushdown automaton has exactly the same expressive power as the original alternating pushdown automaton.

Original language | English |
---|---|

Pages (from-to) | 889-894 |

Number of pages | 6 |

Journal | IEICE Transactions on Information and Systems |

Volume | E90-D |

Issue number | 6 |

DOIs | |

Publication status | Published - 2007 Jun |

### Fingerprint

### Keywords

- Alternating context-free grammar
- Alternating pushdown automaton
- Alternation
- Statealternating context-free grammar

### ASJC Scopus subject areas

- Electrical and Electronic Engineering
- Software
- Artificial Intelligence
- Hardware and Architecture
- Computer Vision and Pattern Recognition

### Cite this

*IEICE Transactions on Information and Systems*,

*E90-D*(6), 889-894. https://doi.org/10.1093/ietisy/e90-d.6.889

**Two ways of introducing alternation into context-free grammars and pushdown automata.** / Moriya, Etsuro; Otto, Friedrich.

Research output: Contribution to journal › Article

*IEICE Transactions on Information and Systems*, vol. E90-D, no. 6, pp. 889-894. https://doi.org/10.1093/ietisy/e90-d.6.889

}

TY - JOUR

T1 - Two ways of introducing alternation into context-free grammars and pushdown automata

AU - Moriya, Etsuro

AU - Otto, Friedrich

PY - 2007/6

Y1 - 2007/6

N2 - Two ways of introducing alternation for context-free grammars and pushdown automata are compared. One is the usual way which combines "states" with alternation [1], [4], [7], and the other is the way used in [6] to define the alternating context-free grammar, i.e., alternation is governed by the variables of the grammar. In this paper the latter way is taken over to define a new type of alternating pushdown automaton by combining the "pushdown symbols" of the pushdown automaton with alternation. We have derived a characterization of the original alternating context-free grammars in terms of such a new type of alternating pushdown automaton without states. It is also shown that, if (non-alternating) states are introduced as an additional feature for this type of pushdown automaton, then the resulting alternating pushdown automaton has exactly the same expressive power as the original alternating pushdown automaton.

AB - Two ways of introducing alternation for context-free grammars and pushdown automata are compared. One is the usual way which combines "states" with alternation [1], [4], [7], and the other is the way used in [6] to define the alternating context-free grammar, i.e., alternation is governed by the variables of the grammar. In this paper the latter way is taken over to define a new type of alternating pushdown automaton by combining the "pushdown symbols" of the pushdown automaton with alternation. We have derived a characterization of the original alternating context-free grammars in terms of such a new type of alternating pushdown automaton without states. It is also shown that, if (non-alternating) states are introduced as an additional feature for this type of pushdown automaton, then the resulting alternating pushdown automaton has exactly the same expressive power as the original alternating pushdown automaton.

KW - Alternating context-free grammar

KW - Alternating pushdown automaton

KW - Alternation

KW - Statealternating context-free grammar

UR - http://www.scopus.com/inward/record.url?scp=56449123223&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=56449123223&partnerID=8YFLogxK

U2 - 10.1093/ietisy/e90-d.6.889

DO - 10.1093/ietisy/e90-d.6.889

M3 - Article

VL - E90-D

SP - 889

EP - 894

JO - IEICE Transactions on Information and Systems

JF - IEICE Transactions on Information and Systems

SN - 0916-8532

IS - 6

ER -