REKERS, J., AND SCH URR, A. A graph grammar approach to graphical parsing. In Proc. IEEE Symposium on Visual Languages (VL'95) (Los Alamitos, CA, 1995), IEEE Computer Society Press, pp. 195--202.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... 2 Related work One important class of syntax definition techniques may be described as grammar based , i.e. syntactical properties are described by productions similar to the way this is done for textual languages, except that the basic structure is not a string but rather a graph (as in e.g. [16, 17]) or a hypergraph [15] These descriptions are then fed to parsers that recognize the language structures in a relatively unstructured collection of input data. Closer to our approach in the style of specification, though very different in the way it is processed, are those parsing algorithms that ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In Proc. 11th IEEE Symposium on Visual Languages, pages 195--202, 1995.

.... abstract syntax and the textual syntax can be partly defined by means of BNF grammars, or BNF like grammars (i.e. BNF grammars enhanced with simple (mathematical) structuring mechanisms such as sets or records) The most popular way of defining the graphical language is by means of graph grammars [20]. In most cases BNF like grammars are not expressive enough to exactly describe which expressions in the language are well formed. Context sensitive properties, such as the declare before use property of variables, must be expressed in a different way. These additional requirements on ....

J. Rekers and A. Sch urr. A graph grammar approach to graphical parsing. In Proceedings of the 1995.

....BNF like grammars (i.e. BNF grammars enhanced with simple (mathematical) structuring mechanisms such as sets or records) For the graphical syntax, no generally accepted format for defining the language exists. The most popular way of defining the graphical language is by means of graph grammars [21]. In most cases BNF like grammars are not expressive enough to exactly describe which expressions in the language are well formed. Context sensitive properties, such as the declare before use property of variables, must be expressed in a di#erent way. These additional requirements on ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In Proceedings of the 1995.

....formalism. 4 Interpreting forms in Higraphs Giving formal syntax and semantics to visual programs is an active research topic. Different extensions of the traditional grammatical formalisms for linear languages have been proposed, leading to a variety of new types of grammars, notably graph [RS95] relational [CGN 91] and constraint multiset [Mar94] General rewrite systems has also been tried as in [NK91] A hierarchical classification of syntax formalisms for visual languages can be found in [Mey91] A logical approach to specification of syntax and semantics has been proposed ....

M. Rekers and A. Schurr. A graph grammar approach to graphical parsing. VL, 1995.

.... S ] atomq, or undirected patom [ S ] atomq, and can also carry edge data. These simple primitives can be combined to produce complex queries. For example, the query [a b,b c] a a,a b,a c,b b,b c,c c] asks which function maps a b c to a b c (Transitive closure) The query ([3,7], 5,1,6] 5,1,6,3,7] asks what function maps the lists [3,7] and [5,1,6] to the list [5,1,6,3,7] List append) The recursive structure of the grammar allows queries to be deeply nested, although this is fairly uncommon. For example, the query [a [1]b,a [3,4]c] 1,3,4] looks for ....

....patom [ S ] atomq, and can also carry edge data. These simple primitives can be combined to produce complex queries. For example, the query [a b,b c] a a,a b,a c,b b,b c,c c] asks which function maps a b c to a b c (Transitive closure) The query ( 3,7] 5,1,6] [5,1,6,3,7] asks what function maps the lists [3,7] and [5,1,6] to the list [5,1,6,3,7] List append) The recursive structure of the grammar allows queries to be deeply nested, although this is fairly uncommon. For example, the query [a [1]b,a [3,4]c] 1,3,4] looks for an algorithm that maps a ....

[Article contains additional citation context not shown here]

J. Rekers and A. Schur. A graph grammar approach to graphical parsing. In VL'95, 1995. 8

.... example, Engels et al. From Trees to Graphs 5 can not be generated by a hyper edge replacement graph grammar, because the number of edges in the graphs generated by such a grammar is bounded [14] For this reason, visual language definitions often have to resort to non context free grammars (cf. [36, 31]) As a consequence, the concept of derivation tree as representation of the process of constructing a sentence is no longer applicable. In fact, in order to record the history of a sentence generated by a context sensitive grammar, a directed acyclic graph (DAG) is required, where the degree of ....

....grammars as well as graph grammars as long as the usual concept of non terminal is present. In the literature on graph grammars, non context free grammars and corresponding notions of concrete and abstract syntax are discussed mainly in the context of visual language definitions (see, e.g. [36, 2, 31, 4, 8] or the survey [5] The theoretical study of such grammars has received relatively little attention. see, however, 27] in this volume) Beside the idea of abstract syntax as a simplified history of the generation of a sentence, which is tightly connected to the use of grammars, in diagram ....

REKERS, J., AND SCH URR, A. A graph grammar approach to graphical parsing. In Proc. IEEE Symposium on Visual Languages (VL'95) (Los Alamitos, CA, 1995), IEEE Computer Society Press, pp. 195--202.

.... for the Graph Grammar community a quite formal version was presented at the Workshop on Graph Grammars and their Application to Computer Science (GraGra 94) see [RS94] For the visual languages world a motivating version was presented at the 11th IEEE Symposium on Visual Languages (VL 95) see [RS95a] 3.3.4 Various Applications Lowe, Korff, and Wagner [LKW91, LKW93] extend the single pushout (SPO) approach to graph transformation to attributed graph transformation. The new theory is further developed in [Wag93] In [Kor92] and [Kor94a] conditional equations functioning as application ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In H.-J. Hoffmann, editor, Proc. VL'95 11th International IEEE Symposium on Visual Languages, 195--202, Darmstadt, Germany, September 1995. Available via ftp from ftp.wi.leidenuniv.nl as /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

.... for the Graph Grammar community a quite formal version was presented at the Workshop on Graph Grammars and their Application to Computer Science (GraGra 94) see [RS94] For the visual languages world a motivating version was presented at the 11th IEEE Symposium on Visual Languages (VL 95) see [RS95a] 4.5 Various Applications Lowe, Korff, and Wagner [LKW91, LKW93] extend the single pushout (SPO) approach to graph transformation to attributed graph transformation. The new theory is further developed in [Wag93] In [Kor92] and [Kor94] conditional equations functioning as application ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In H.-J. Hoffmann, editor, Proc. VL'95 11th International IEEE Symposium on Visual Languages, 195-- 202, Darmstadt, Germany, September 1995. Available via ftp from ftp.wi.leidenuniv.nl as /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

....nonterminal directed nonempty graph no yes implicitly def. vertex ordering by edges linear Rozenberg Welzl [89] one nonterminal directed graph without nonterminal neighbours no yes (bounded degree, connected graph) exponential (polynomial) Graph Rekers Sch urr [85] directed graph directed connected, nonempty graph directed graph extended context global layering condition for grammar exponential Zhang Zhang [120] directed graph directed connected, nonempty graph directed graph extended context confluent grammar polynomial Bunke ....

....relationships between them. Minas s parsers [69] for hypergraph grammars are also inspired by the CockeYounger Kasami parser. The first one is restricted to purely context free hypergraph grammars, the second allows to parse context free grammars with embeddings. Rekers and Schurr s parser [85] for layered graph grammars is able to deal with nearly unrestricted graph grammars. The only restriction is a layering restriction which ensures that parsing is alway terminating. Minas s as well as Rekers and Schurr s parsers are discussed in more detail in the following subsections. Zhang and ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In [113], pages 195--202, 1995. Available from ftp.wi.leidenuniv.nl, file /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

.... for the Graph Grammar community a quite formal version was presented at the Workshop on Graph Grammars and their Application to Computer Science (GraGra 94) see [RS94] For the visual languages world a motivating version was presented at the 11th IEEE Symposium on Visual Languages (VL 95) see [RS95a]. 3.3.5 Various Applications In [MP94a] Maggiolo Schettini and Peron propose graph rewriting as a proper abstract machine for defining an operational semantics for the specification formalism Statecharts. A statechart is translated into a set of graph productions and steps from configuration ....

Jan Rekers and Andy Schurr. A graph grammar approach to graphical parsing. In H.-J. Hoffmann, editor, Proc. VL'95 11th International IEEE Symposium on Visual Languages, 195--202, Darmstadt, Germany, September 1995. Available via ftp from ftp.wi.leidenuniv.nl as /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

....succeeds, otherwise it is not. For context free and restricted context sensitive hypergraph grammars, this problem is more or less efficiently decidable [12] For the general grammar, this problem is no longer decidable. For certain restricted graph grammars 4 , e.g. layered graph grammars [17], there are special parsing algorithms, however they are quite inefficient. Recently, the class off reserved graph grammars (RGGs) 28] has been proposed which allows for a straight forward way to parse hypergraphs. 5 The derivation for a hypergraph H is 4 In the literature, mainly graphs as ....

....diagrams. Flowgraphs can be considered as a special case of hypergraphs used in this paper. The chart parser can be used top down as well as bottom up for context free flow grammars only. Rekers and Schurr have proposed a graph parser for more general grammars, so called layered graph grammars [17]. Their parsing algorithm uses a bottom up and then a top down phase to (re)construct derivation sequences of the graph given. Finally, Zhang and Zhang have proposed an efficient parser even for context sensitive reserved graph grammars based on Rekers and Schurr s one [28] However, the ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In [25], pages 195--202, 1995.

....complexity Kaul [82,83] one nonterminal directed nonempty graph no yes implicitly def. vertex ordering by edges linear Rozenberg Welzl [84] one nonterminal directed graph without nonterminal neighbours no yes (bounded degree, connected graph) exponential (polynomial) Graph Rekers Sch urr [85] directed graph directed connected, nonempty graph directed graph extended context global layering condition for grammar exponential Zhang Zhang [86] directed graph directed connected, nonempty graph directed graph extended context confluent grammar polynomial Bunke Haller [87] one ....

....relationships between them. Minas s parsers [88] for hypergraph grammars are also inspired by the CockeYounger Kasami parser. The first one is restricted to purely context free hypergraph grammars, the second allows to parse context free grammars with embeddings. Rekers and Schurr s parser [85] for layered graph grammars is able to deal with nearly unrestricted graph grammars. The only restriction is a layering restriction which ensures that parsing is alway terminating. Minas s as well as Rekers and Schurr s parsers are discussed in more detail in the following subsections. Zhang and ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In [1], pages 195--202, 1995. Available from ftp.wi.leidenuniv.nl, file /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

....are based on extensions of string grammar formalisms. A complete and recent overview is out of scope of this paper. However, we like to mention a few approaches: generalizations of attributed grammars (e.g. picture layout grammars [20] positional grammars (e.g. 21] and graph grammars (e.g. [22, 23, 24]) Other approaches closely related to this one use (constraint) logic or relational formalisms (e.g. 25, 26, 27, 28, 29, 30] to represent spatial relationships. Experience has shown (reported by Wittenburg in [29] that some grammar approaches have limitations (e.g. no arbitrary ordering of ....

J. Rekers and A. Schurr, "A Graph Grammar Approach to Graphical Parsing", In VL'95 [36], pp. 195--202.

....oval touch oval inside inside Appl oval touch oval inside arrow Fun touch VEX inside inside oval touch oval inside arrow Fun touch Var inside inside Figure 8: A sample derivation using the VEX grammar. longer decidable. For certain restricted graph grammars 3 as the layered graph grammars (Rekers and Schurr, 1995) there are special parsing algorithms, however they are quite inefficient. Recently, the class off reserved graph grammars (RGGs) Zhang and Zhang, 1997) has been proposed which allows for a straight forward way to parse hypergraphs. 4 The derivation for a hypergraph H is reconstructed by ....

Rekers, J. and Schurr, A. (1995). A graph grammar approach to graphical parsing. In VL'95 (1995), pages 195--202.

....as a special kind of diagrams. Flowgraphs can be considered as a special case of hypergraphs used in this paper. The chart parser can be used top down as well as bottom up for context free flow grammars only. Rekers and Schurr have proposed a graph parser not restricted to context free grammars [17]. Their parsing algorithm uses a bottom up and then a top down phase to (re)construct derivation sequences of the graph given. In opposition to the parser proposed in this paper, they have not focussed on incremental parsing and analyzing syntactically incorrect graphs with correct sub graphs. The ....

J. Rekers and A. Schurr, "A graph grammar approach to graphical parsing", In VL'95 [21], pp. 195--202.

....Mostly, these approaches extend string grammar formalisms. A complete and recent overview is out of scope of this paper. However, we like to mention a few approaches: generalizations of attributed grammars (e.g. picture layout grammars [12] positional grammars (e.g. 13] graph grammars (e.g. [14, 15, 16]) and algebraic or type theoretic formalisms (e.g. 17, 18] Other work closely related to our approach uses (constraint) logic or relational formalisms (e.g. 19, 20, 21, 22, 23, 24, 25] for representing spatial relationships. A more detailed review of closely related work on VL theory can be ....

J. Rekers and A. Schurr, "A Graph Grammar Approach to Graphical Parsing", In VL'95 [29], pp. 195-- 202.

....AE97] Graph Rewrite Systems and Visual Database Languages. Use of attributed and labeled graphs (PROGRES [Zun92, SZW95] defines syntax and semantics of a visual database language; without considerations wrt. graphical structure. 4. Rekers Schurr Engels Andries in [Rek94, Sch94, RS95b, RS95a, AER96, RS96] How to represent a Visual Program and A graph based framework for the implementation of visual environments Use of attributed and labeled graphs (PROGRES [Zun92, SZW95] defines syntax of visual languages, graphical parsing, and a graph based framework; with considerations ....

....(called abstract syntax) as well as to define the view (called spatial relations) of diagrammatic expressions. Sch94] provides triple graph grammars to hold theses two structures, which is said to define a visual language. Within following articles graphical (context sensitive) parsing ( RS95b, RS95a] is regarded, and it is more concrete defined how to represent a visual program ( AER96] corresponding to the two structures mentioned above. Figure 6 illustrates the several representations of a visual program. Within the last contribution ( RS96] a graph based framework for the ....

J. Rekers and A. Schurr. A Graph Grammar Approach to Graphical Parsing. In [VL'95], 1995.

....of a string to a box, or a circle being contained in another circle) as edges between them. See figure 1 for a simple example. The second stage, the actual parser, analyzes the resulting graph by interpreting it as an expression in a graph grammar using an algorithm developed by Rekers and Schurr [17, 14, 15, 13]. It is this algorithm that this report focuses on. The aim is to determine the practical usefulness of the approach, and of the parsing algorithm in particular, by providing an implementation and studying its behaviour, as well as the friendliness of the language formalism used. It will become ....

....by the parser is a relatively meaningless data structure and it may well be desirable to further process it before feeding it back to the application, kneading it into a more useful form. Several suggestions for such further processing (generally described as high level parsing) are summarized in [15], the most interesting perhaps being that of coupled graph grammars. This approach could be used to formalize the translation from a parse tree to an abstract syntax tree which is usually much closer to the application s perception of the structure of its input. Figure 2 shows a small but ....

[Article contains additional citation context not shown here]

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In Proceedings 11th IEEE Symposium on Visual Languages -- VL'95, pages 195--202, 1995. Available from ftp.wi.leidenuniv.nl, file /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

.... Arrow State State State Transition State from to String labels repr repr repr repr repr repr starts ends 1 2 3 4 1 2 3 4 Figure 2: Graph grammar definition of a Transition meaning of a visual database query language may be specified by means of a graph grammar; Rekers and Schurr [11] use a single graph grammar to specify the syntax of visual languages. Here we take this work further by making the distinction between spatial relations graph and abstract syntax graph. A quick overview of graph grammars: A graph grammar GG consists of an axiom graph A and a collection of ....

....graph. ffl Direct manipulation of the graphical objects 2 is allowed within the limits imposed by the constraints and is guaranteed not to change the interpretation of the diagram. ffl Free editing of the diagram can be implemented with help of the graph parser as developed by Rekers and Schurr[11]. This parser then works according to the SRG part of the grammar, and the ASG can be reconstructed as side effect. In the introduction we have made a very strict distinction between the Spatial Relations Graph, the Abstract Syntax Graph, and their connection, while the graph grammar definition ....

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In Proceedings 11th IEEE symposium on Visual Languages -- VL'95, pages 195-- 202, 1995. Available from ftp.wi.leidenuniv.nl, file /pub/CS/TechnicalReports/1995/tr95-15.ps.gz.

....thus to define the syntax of visual languages. This claim is supported by prior work of the authors of this paper: Andries and Engels [And96, AE96] demonstrate how both abstract syntax and meaning of a visual database query language may be specified by means of a graph grammar; Rekers and Schurr [RS95] use a single graph grammar to specify the syntax of visual languages. Here we take this work further by making the distinction between spatial relations graph and abstract syntax graph. A quick overview of graph grammars: A graph grammar GG consists of an axiom graph A and a collection of ....

....ffl Direct manipulation of the graphical objects 2 is allowed within the limits imposed by the constraints and is guaranteed not to change the interpretation of the diagram. ffl Free editing of the diagram can be implemented with help of the graph parser as developed by Rekers and Schurr [RS95]. This parser then works according to the SRG part of the grammar, while the ASG can be reconstructed as side effect. Due to the context sensitiveness of the PROGRES graph grammar, the parsing algorithm is in general of exponential time complexity. But, in addition to the arguments given in this ....

[Article contains additional citation context not shown here]

J. Rekers and A. Schurr. A graph grammar approach to graphical parsing. In Proceedings 11th IEEE Symposium on Visual Languages -- VL'95, pages 195--202, 1995. Available from ftp.wi.leidenuniv.nl, file /pub/CS/TechnicalReports/1995/tr9515. ps.gz.

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REKERS, J., AND SCH URR, A. A graph grammar approach to graphical parsing. In Proc. IEEE Symposium on Visual Languages (VL'95) (Los Alamitos, CA, 1995), IEEE Computer Society Press, pp. 195--202.

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