The Failure of the Strong Pumping Lemma for Multiple Context-Free Languages
Seki et al. (Theor. Comput. Sci. 88(2):191–229, 1991 ) showed that every m -multiple context-free language L is weakly 2 m -iterative in the sense that either L is finite or L contains a subset of the form , where w 1 ⋯ w 2 n ≠ ε . Whether every m -multiple context-free language L is 2 m -iterative,...
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| Published in: | Theory of computing systems Vol. 55; no. 1; pp. 250 - 278 |
|---|---|
| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Boston
Springer US
01.07.2014
Springer Nature B.V Springer Verlag |
| Subjects: | |
| ISSN: | 1432-4350, 1433-0490 |
| Online Access: | Get full text |
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| Summary: | Seki et al. (Theor. Comput. Sci. 88(2):191–229,
1991
) showed that every
m
-multiple context-free language
L
is weakly 2
m
-iterative in the sense that either
L
is finite or
L
contains a subset of the form
, where
w
1
⋯
w
2
n
≠
ε
. Whether every
m
-multiple context-free language
L
is 2
m
-iterative, that is to say, whether all but finitely many elements
z
of
L
can be written as
z
=
u
0
w
1
u
1
⋯
w
2
m
u
2
m
with
w
1
⋯
w
2
m
≠
ε
and
, has been open. We show that there is a 3-multiple context-free language that is not
k
-iterative for any
k
. |
|---|---|
| Bibliography: | SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-2 content type line 23 |
| ISSN: | 1432-4350 1433-0490 |
| DOI: | 10.1007/s00224-014-9534-z |