Hypergraph systems generating graph languages

Author(s):  
D. Janssens ◽  
G. Rozenberg



2001 ◽  
Vol 11 (5) ◽  
pp. 637-688 ◽  
Author(s):  
ANNEGRET HABEL ◽  
JÜRGEN MÜLLER ◽  
DETLEF PLUMP

In this paper we investigate and compare four variants of the double-pushout approach to graph transformation. As well as the traditional approach with arbitrary matching and injective right-hand morphisms, we consider three variations by employing injective matching and/or arbitrary right-hand morphisms in rules. We show that injective matching provides additional expressiveness in two respects: for generating graph languages by grammars without non-terminals and for computing graph functions by convergent graph transformation systems. Then we clarify for each of the three variations whether the well-known commutativity, parallelism and concurrency theorems are still valid and – where this is not the case – give modified results. In particular, for the most general approach with injective matching and arbitrary right-hand morphisms, we establish sequential and parallel commutativity by appropriately strengthening sequential and parallel independence.



1987 ◽  
Vol 16 (1) ◽  
pp. 59-73 ◽  
Author(s):  
Grzegorz Rozenberg ◽  
Emo Welzl


Author(s):  
Philip R. Holland
Keyword(s):  




10.37236/9802 ◽  
2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Peter Cameron ◽  
Saul Freedman ◽  
Colva Roney-Dougal

For a nilpotent group $G$, let $\Xi(G)$ be the difference between the complement of the generating graph of $G$ and the commuting graph of $G$, with vertices corresponding to central elements of $G$ removed. That is, $\Xi(G)$ has vertex set $G \setminus Z(G)$, with two vertices adjacent if and only if they do not commute and do not generate $G$. Additionally, let $\Xi^+(G)$ be the subgraph of $\Xi(G)$ induced by its non-isolated vertices. We show that if $\Xi(G)$ has an edge, then $\Xi^+(G)$ is connected with diameter $2$ or $3$, with $\Xi(G) = \Xi^+(G)$ in the diameter $3$ case. In the infinite case, our results apply more generally, to any group with every maximal subgroup normal. When $G$ is finite, we explore the relationship between the structures of $G$ and $\Xi(G)$ in more detail.



2011 ◽  
Vol 09 (01) ◽  
pp. 547-554
Author(s):  
HONG XIE ◽  
MEI-XIANG CHEN

A scheme is proposed for generating graph-state entanglement between many atomic ensembles. In this scheme, the photons are transferred from the single-"spin" excitations of the atomic ensembles via the dipole blockade mechanism, which act as ancillary qubits and interfere with each other on linear optics apparatus. The quantum-entangled state of the atomic ensembles can be obtained under the conditional detection of the photons. Since the single-"spin" excitations can be deterministically created via strong long-range dipole–dipole interaction and the transferred efficiency is enhanced by the many-atom interference effects, our scheme can work with a high probability of success.



Author(s):  
Sei'ichi Tani ◽  
Koichi Yamazaki
Keyword(s):  




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