scholarly journals IO and OI

1975 ◽  
Vol 4 (47) ◽  
Author(s):  
Joost Engelfriet ◽  
Erik Meineche Schmidt
Keyword(s):  
Fixed Point ◽  
Program Scheme ◽  
Closure Properties ◽  
Recursive Program ◽  
Tree Languages ◽  
Emptiness Problem ◽  
Free Tree ◽  
Context Free ◽  
Inside Out

A fixed point characterization of the inside-out (IO) and the outside- in (OI) context-free tree languages is given. This characterization is used to obtain a theory of nondeterministic systems of context-free equations with parameters. Several ''Mezei and Wright like'' results are obtained which relate to context-free tree languages, to recognizable tree languages and to nondeterministic recursive program(scheme)s (called by value and called by name). The emptiness problem and closure properties of the context-free tree languages are discussed. Hierarchies of higher level equational subsets of an algebra are considered.

Some results on top-context-free tree languages

2005 ◽  
pp. 157-171 ◽  
Author(s):  
Dieter Hofbauer ◽  
Maria Huber ◽  
Gregory Kucherov
Keyword(s):  
Tree Languages ◽  
Free Tree ◽  
Context Free

scholarly journals Linear context-free tree languages and inverse homomorphisms

2019 ◽  
Vol 269 ◽  
pp. 104454 ◽  
Author(s):  
Johannes Osterholzer ◽  
Toni Dietze ◽  
Luisa Herrmann
Keyword(s):  
Tree Languages ◽  
Free Tree ◽  
Context Free

A bottom-up parsing method for complete context-free tree languages

1986 ◽  
Vol 17 (3) ◽  
pp. 66-74
Author(s):  
Kyota Aoki ◽  
Kazumi Matsuura
Keyword(s):  
Bottom Up ◽  
Tree Languages ◽  
Free Tree ◽  
Context Free

Regular Approximation of Weighted Linear Context-Free Tree Languages

2017 ◽  
Vol 28 (05) ◽  
pp. 523-542
Author(s):  
Markus Teichmann
Keyword(s):  
Tree Language ◽  
Regular Tree ◽  
Tree Grammar ◽  
Regular Approximation ◽  
Leibler Divergence ◽  
Tree Languages ◽  
Free Tree ◽  
Context Free

We show how to train a weighted regular tree grammar such that it best approximates a weighted linear context-free tree grammar concerning the Kullback–Leibler divergence between both grammars. Furthermore, we construct a regular tree grammar that approximates the tree language induced by a context-free tree grammar.

scholarly journals Context-Free Tree Languages for Descendants

2005 ◽  
Vol 124 (1) ◽  
pp. 81-96
Author(s):  
P RETY ◽  
J VUOTTO
Keyword(s):  
Tree Languages ◽  
Free Tree ◽  
Context Free

scholarly journals Fixed-point characterization of context-free ∞-languages

1984 ◽  
Vol 61 (3) ◽  
pp. 247-276 ◽  
Author(s):  
Damian Niwiński
Keyword(s):  
Fixed Point ◽  
Context Free

RECOGNIZABLE PICTURE LANGUAGES

1992 ◽  
Vol 06 (02n03) ◽  
pp. 241-256 ◽  
Author(s):  
DORA GIAMMARRESI ◽  
ANTONIO RESTIVO
Keyword(s):  
Two Dimensional ◽  
Closure Properties ◽  
One Dimensional ◽  
New Family ◽  
The Family ◽  
Emptiness Problem ◽  
Picture Languages ◽  
Local Languages

The purpose of this paper is to propose a new notion of recognizability for picture (two-dimensional) languages extending the characterization of one-dimensional recognizable languages in terms of local languages and alphabetic mappings. We first introduce the family of local picture languages (denoted by LOC) and, in particular, prove the undecidability of the emptiness problem. Then we define the new family of recognizable picture languages (denoted by REC). We study some combinatorial and language theoretic properties of REC such as ambiguity, closure properties or undecidability results. Finally we compare the family REC with the classical families of languages recognized by four-way automata.

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