On logics, tilings, and automata
Proceedings of the 18th international colloquium on Automata, languages and programming
T-structures, T-functions, and texts
Theoretical Computer Science
Monadic second-order definable graph transductions: a survey
Theoretical Computer Science - Selected papers of the 17th Colloquium on Trees in Algebra and Programming (CAAP '92) and of the European Symposium on Programming (ESOP), Rennes, France, Feb. 1992
Acta Informatica
On a monadic NP vs monadic co-NP
Information and Computation
Text languages in an algebraic framework
Fundamenta Informaticae - Special issue on formal language theory
Handbook of formal languages, vol. 3: beyond words
Handbook of formal languages, vol. 3: beyond words
Languages, automata, and logic
Handbook of formal languages, vol. 3
On Piecewise Testable, Starfree, and Recognizable Picture Languages
FoSSaCS '98 Proceedings of the First International Conference on Foundations of Software Science and Computation Structure
The monadic quantifier alternation hierarchy over grids and graphs
Information and Computation - Special issue: LICS'97
Journal of Automata, Languages and Combinatorics
Definable transductions and weighted logics for texts
DLT'07 Proceedings of the 11th international conference on Developments in language theory
Definable transductions and weighted logics for texts
Theoretical Computer Science
Two variables and two successors
MFCS'10 Proceedings of the 35th international conference on Mathematical foundations of computer science
| Hi-index | 5.23 |
As is well known, a language of finite words, considered as labeled linear orders, is definable in monadic second-order logic (MSO) iff it is definable in the existential fragment of MSO, that is the quantifier alternation hierarchy collapses. Even more, it does not make a difference if we consider existential MSO over a linear order or a successor relation only. In this note we show that somewhat surprisingly the latter does not hold if we just add a second linear order and consider finite relational structures with two linear orders, so-called texts.