Searching for authors named "Denis Lapoire" – sorted by Relevance.
4 documents found, showing 1 through 4.
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Treewidth and Duality for Planar Hypergraphs.
- …We prove a conjecture of Robertson and Seymour (Graph Minors. III. Planar tree-width): the treewidth of a planar graph is at most the treewidth of its dual plus one. To this purpose, we study hypermaps, which represent hypergraphs on a surface. We dene a parallel composition on hypermaps which v…
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Recognizability equals Monadic Second-Order definability, for sets of graphs of bounded tree-width.
- …We prove that for each k, there exists a MSO-transduction that associates with every graph of tree-width at most k one of its treedecompositions of width at most k. Courcelle proves in (The Monadic secondorder logic of graphs, I: Recognizable sets of finite graphs) that every set of graphs is recogn…
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Facial Circuits of Planar Graphs and Context-Free Languages.
- …It is known that a language is context-free iff it is the set of borders of the trees of recognizable set, where the border of a (labelled) tree is the word consisting of its leaf labels read from left to right. We give a generalization of this result in terms of planar graphs of bounded tree-wi…
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Criteria to Disprove Context-Freeness of Collage Languages
- …. Collage grammars generate picture languages in a context-free way. The generating process is based on the replacement of atomic nonterminal items and can be seen as an adaptation of the notion of hyperedge replacement known from the area of context-free graph generation. While a pumping lemma hold…
- Cited by 5 (4 self) – Add To MetaCart
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