P. J. Rodgers and P. J. H. King. A graph-rewriting visual language for database programming. Journal of Visual Languages and Computing, 8:641--674, 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the LH pattern as being a subgraph of the forms schema. The reason for this is that some productions require particular nodes and edges to be absent from a forms schema for a successful embedding to occur. To deal with this situation a scheme of positive and negative nodes and edges is adopted [16] (negative nodes edges are shown in bold in figure 3(a) Under this scheme an embedding of a graph in a host graph is successful if only postive nodes and edges are found to be a subgraph of the host graph. The substituted pattern in figure 4, for example, can be embedded in the forms schema of ....

P. J. Rodgers and P. J. H. King. A graph-rewriting visual language for database programming. Journal of Visual Languages and Computing, 8:641--674, 1997.

....do not capture the concept of hierarchy (except for inheritance) Both these models lack the possibility to represent explicit relationships and query them as first class objects in the system, and do not offer a means to represent overlapping classifications. Graph models (e.g. PL94] Gemis96] [RK97]) provide the hierarchical aspect, the possibility of graph traversing exploration of the content of the database (e.g. BDS95] and the modelling of data of any degree of complexity. However, this model lacks expressiveness. Indeed, graph models are generally simple data models and are not ....

P. J. Rodgers, P. J. H. King, "A graph rewriting visual language for database programming", Journal of Visual Languages & Computing Vol. 8 Issue 5/6, pp 641-674 (1997)

....guides user applications when data is inserted in the database. As a taxonomic classification hierarchy is a tree like structure, it would seem an intuitive choice to model it using a structure that is inherently hierarchic. Candidate graph systems are GOOD [Gemis96] Hyperlog [PL94] and Spider [RK97]. Graph oriented databases are a recent area of research, and there is no unanimously accepted model or system. Rather, there are many proposed models that differ slightly from each other (e.g. they differ on where the information is stored, on labelled nodes (e.g. Hyperlog) on labelled edges, or ....

P. J. Rodgers, P. J. H. King, "A graph rewriting visual language for database programming", Journal of Visual Languages & Computing Vol. 8 Issue 5/6, pp 641-674 (1997)

....provide taxonomists with means of manipulating taxonomic data naturally and effectively. Since taxonomists are not computing specialists, the choice of graphs also has the advantage of being naturally represented graphically and easily coupled with a graphical programming language (e.g. PL94] [RK97]) First we define briefly the Prometheus model in section 2, then we explain the operations necessary on graphs in section 3. In section 4 we describe the structure and the properties of our patterns and in section 5 we build a database example and show how it works. Finally we conclude in ....

P. J. Rodgers, P. J. H. King, "A graph rewriting visual language for database programming", Journal of Visual Languages & Computing Vol. 8 Issue 5/6, pp 641-674 (1997)

....have to be considered. Finally, it is worth mentioning that there are other potential applications of visual languages to NLP. In particular, a visual approach to parsing seems promising as both the connection between parsing and graph grammars [11] and between graph grammars and visual languages [15, 16] has already been made. Another application area concerns graph based semantic network representations which are widely used for knowledge representation by NLP systems [17] Visual languages that examine the structure of graphs [3] could be used when manipulating such data. Acknowledgements The ....

P. Rodgers and P. King. A Graph Rewriting Visual Language for Database Programming. The Journal of Visual Languages and Computing, In press.

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