Fractals everywhere
A survey of two-dimensional automata theory
Selected contributions of the fifth international meeting of Young Computer Scientists on Machines, language, and complexity
Efficient detection of quasiperiodicities in strings
Theoretical Computer Science
Handbook of formal languages, vol. 3
A characterization of recognizable picture languages by tilings by finite sets
Theoretical Computer Science - Special issue on Caen '97
Proceedings of the 4th International Workshop on Graph-Grammars and Their Application to Computer Science
Theoretical Computer Science - In honour of Professor Christian Choffrut on the occasion of his 60th birthday
Picture languages: tiling systems versus tile rewriting grammars
Theoretical Computer Science - In honour of Professor Christian Choffrut on the occasion of his 60th birthday
Characterizations of recognizable picture series
Theoretical Computer Science
Two-way finite automata with a write-once track
Journal of Automata, Languages and Combinatorics
ISVC '08 Proceedings of the 4th International Symposium on Advances in Visual Computing, Part II
Picture Languages: From Wang Tiles to 2D Grammars
CAI '09 Proceedings of the 3rd International Conference on Algebraic Informatics
Collage of iso-picture languages and P-systems
CompIMAGE'10 Proceedings of the Second international conference on Computational Modeling of Objects Represented in Images
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We consider a new operation on one-dimensional (resp. two-dimensional) word languages, obtained by piling up, one on top of the other, words of a given recognizable language (resp. two-dimensional recognizable language) on a previously empty one-dimensional (resp. two-dimensional) array. The resulting language is the set of words "seen from above": a position in the array is labeled by the topmost letter. We show that in the one-dimensional case, the language is always recognizable. This is no longer true in the two-dimensional case which is shown by a counter-example, and we investigate in which particular cases the result may still hold.