## A Nested-Graph Model for the Representation and Manipulation of Complex Objects (1994)

Venue: | ACM Transactions on Information Systems |

Citations: | 36 - 4 self |

### BibTeX

@ARTICLE{Poulovassilis94anested-graph,

author = {Alexandra Poulovassilis and Mark Levene},

title = {A Nested-Graph Model for the Representation and Manipulation of Complex Objects},

journal = {ACM Transactions on Information Systems},

year = {1994},

volume = {12},

pages = {35--68}

}

### Years of Citing Articles

### OpenURL

### Abstract

this paper we report upon a graph-based approach to such an integration. Our use of graphs has two key advantages : firstly, graphs are formally defined, well-understood structures; secondly, it is widely accepted that graph-based formalisms considerably enhance the usability of complex systems [19]. Graphs have been used in conjunction with a number of conventional data models, for example the hierarchical and network models [35], the entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in [12, 17, 23, 25, 33, 36] as a data modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper. Directed graphs have also been the foundation of Hypertext databases [11, 33]. Such databases are graphs consisting of nodes which refer to units of stored information (typically text) and of named links. Each link connects two nodes, the "source" and the "destination". Links are traversed either forwards (from source to destination) or backwards (from destination to source). The process of traversing named links and examining the text associated with nodes is called

### Citations

10922 |
Computers and Intractability: A Guide to the Theory of NP-Completeness
- Garey, Johnson
- 1979
(Show Context)
Citation Context ...a match for a query, q, with respect to a repository, HR, is NPcomplete. PROOF. We first show NP-Hardness by showing that this problem contains sub-graph isomorphism, which is known to be NP-Complete =-=[15]-=-, as a sub-problem. Let Q be a positive query of the form G = (N+, E+), where the elements of N+ are all variables of the same type, and let there be an equation G = (N, E) in HR. The result follows s... |

1355 | The Entity-Relationship Model: Toward a Unified View
- Chen
- 1976
(Show Context)
Citation Context ... usability of complex systems [19]. Graphs have been used in conjunction with a number of conventional data models, for example the hierarchical and network models [35], the entity-relationship model =-=[9]-=- and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in [12, 17, 23, 25, 33, 36] as a da... |

1064 |
Principles of Database and Knowledge-Base Systems. Volume II: The New Technologies
- Ullman
- 1989
(Show Context)
Citation Context ... formalisms considerably enhance the usability of complex systems [19]. Graphs have been used in conjunction with a number of conventional data models, for example the hierarchical and network models =-=[35]-=-, the entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently ... |

682 |
Hypertext: an introduction and survey
- Conklin
- 1987
(Show Context)
Citation Context ...a modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper. Directed graphs have also been the foundation of Hypertext databases =-=[11, 33]. Such databases are-=- graphs consisting of nodes which refer to units of stored information (typically text) and of named links. Each link connects two nodes, the "source" and the "destination". Links ... |

544 | On Visual Formalisms
- Harel
- 1988
(Show Context)
Citation Context ...wo key advantages : firstly, graphs are formally defined, well-understood structures; secondly, it is widely accepted that graph-based formalisms considerably enhance the usability of complex systems =-=[19]-=-. Graphs have been used in conjunction with a number of conventional data models, for example the hierarchical and network models [35], the entity-relationship model [9] and a recent extension thereof... |

500 |
Graphs and Hypergraphs
- Berge
- 1973
(Show Context)
Citation Context ...e hierarchical and network models [35], the entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs =-=[6]-=- have also been used more recently in [12, 17, 23, 25, 33, 36] as a data modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper... |

297 |
Object identity as a query language primitive
- Abiteboul, Kanellakis
- 1989
(Show Context)
Citation Context ... the two paradigms. The integration has generally taken the route of extending logic-based deductive database languages with features such as object identity, sets, functions, methods and inheritance =-=[1, 2, 3, 14]-=-. In contrast, in this paper we report upon a graph-based approach to such an integration. Our use of graphs has two key advantages : firstly, graphs are formally defined, well-understood structures; ... |

259 |
The Functional Data Model and the Data Language DAPLEX
- Shipman
- 1981
(Show Context)
Citation Context ...ed, extensional, tuples. These derived tuples can be used purely for querying purposes or can be inserted into the database. Conversely, object-oriented databases start off with a semantic data model =-=[16, 20, 31]-=-, which typically supports object identity, inheritance and complex objects, and extend it with features such as methods and encapsulation from object-oriented programming [32, 37]. Thus, deductive an... |

245 | Extending the database relational model to capture moremeaning
- Codd
- 1979
(Show Context)
Citation Context ...aring in the equations of HR. For example, the four equations above satisfy the criteria for a hypernode repository. We note that condition H1 above corresponds to the entity integrity requirement of =-=[10]-=- since each equation can viewed as representing a real-world entity. Similarly, condition H2 corresponds to the referential integrity requirement of [10] since it requires that only existing entities ... |

228 | Semantic database modelling: Survey, applications and research issues
- Hull, King
- 1987
(Show Context)
Citation Context ...ed, extensional, tuples. These derived tuples can be used purely for querying purposes or can be inserted into the database. Conversely, object-oriented databases start off with a semantic data model =-=[16, 20, 31]-=-, which typically supports object identity, inheritance and complex objects, and extend it with features such as methods and encapsulation from object-oriented programming [32, 37]. Thus, deductive an... |

166 | GraphLog: a visual formalism for real life recursion
- Consens, Mendelzon
(Show Context)
Citation Context ...he entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in =-=[12, 17, 23, 25, 33, 36]-=- as a data modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper. Directed graphs have also been the foundation of Hypertext d... |

166 |
The relational model with relation-valued attributes
- Schek, Scholl
- 1986
(Show Context)
Citation Context ...oded in the update programs in Hyperlog. Given a record type T, we can represent a relation type as set(T). The component types of a record type may themselves be record types and so nested relations =-=[30]-=- can also be represented. The types FLIGHT of Figure 4 and TICKET of Figure 5 illustrate nested relation types. Given types T 1 and T 2 , we can represent a mapping type T = T 1 T 2 as T = ({T 1 , T 2... |

147 | A Logical Language for Data and Knowledge Bases - Naqvi, Tsur - 1989 |

117 |
Computable queries for relational data bases
- Chandra, Harel
- 1980
(Show Context)
Citation Context ... of Hyperlog with respect to database updates. We first define what an update is in our context and then define the concept of update completeness, by analogy to previous work in relational databases =-=[1, 8]-=-. Given a type repository TR, we define the set inst(TR) to contain all hypernode repositories which are well-typed with respect to TR. We define an update to be a partial recursive mapping from inst(... |

109 |
On Closed World databases
- Reiter
- 1978
(Show Context)
Citation Context ...ion q is a match for this set of queries if it is a match for each query q i taken separately. We note that in the above definition we are assuming a Herbrand Universe and the Closed World Assumption =-=[29]-=-. This allows us to infer the negation of a node or edge in the absence of a positive match c.f. other non-monotonic formalisms [28]. For example, given a hypernode repository containing the following... |

79 |
Algorithmics: The Spirit of Computing
- Harel
- 1987
(Show Context)
Citation Context ...tionally complete and update complete. We first demonstrate the computational completeness of Hyperlog by showing that it can simulate counter programs, which are known to be computationally complete =-=[18]-=-. Counter programs manipulate natural numbers which are stored in variables called counters. Four operations are allowed on counters : X := 0, X := Y, X := X + 1 and X := X - 1, where X and Y are coun... |

73 |
Object-oriented databases: Definition and research directions
- Kim
- 1990
(Show Context)
Citation Context ...Phrases : Nested graph, complex object, types, rule-based query and update language, object store. 2 1. INTRODUCTION Recent database research has focussed on deductive [7, 14, 26] and object-oriented =-=[5, 22]-=- databases. Deductive databases extend the relational data model with rule-based computation. Rules enable the derivation of further, intentional, tuples from the stored, extensional, tuples. These de... |

60 |
Procedural and declarative database update languages
- Abiteboul, Vianu
- 1988
(Show Context)
Citation Context ... the two paradigms. The integration has generally taken the route of extending logic-based deductive database languages with features such as object identity, sets, functions, methods and inheritance =-=[1, 2, 3, 14]-=-. In contrast, in this paper we report upon a graph-based approach to such an integration. Our use of graphs has two key advantages : firstly, graphs are formally defined, well-understood structures; ... |

56 |
A New Approach to Database Logic
- Kuper, Vardi
- 1984
(Show Context)
Citation Context ...he entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in =-=[12, 17, 23, 25, 33, 36]-=- as a data modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper. Directed graphs have also been the foundation of Hypertext d... |

55 |
A data model for flexible hypertext database systems
- Tompa
- 1989
(Show Context)
Citation Context ...he entity-relationship model [9] and a recent extension thereof for complex objects [27], and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in =-=[12, 17, 23, 25, 33, 36]-=- as a data modelling tool in their own right. We give a comparison between this recent work and our own approach in Section 4 of the paper. Directed graphs have also been the foundation of Hypertext d... |

54 | Semantic Issues in Deductive Databases and Logic Programs
- Przymusinska, Przymusinski
- 1990
(Show Context)
Citation Context ...we are assuming a Herbrand Universe and the Closed World Assumption [29]. This allows us to infer the negation of a node or edge in the absence of a positive match c.f. other non-monotonic formalisms =-=[28]-=-. For example, given a hypernode repository containing the following routes : R1 = ({flight_no,605,airline,AIR1,from,to ... }, {flight_no605, airlineAIR1 ... }) R2 = ({flight_no,301,airline,AIR2,from,... |

40 |
Fixpoint extensions of first-order logic and Dataloglike languages
- Abiteboul, Vianu
- 1989
(Show Context)
Citation Context ... the two paradigms. The integration has generally taken the route of extending logic-based deductive database languages with features such as object identity, sets, functions, methods and inheritance =-=[1, 2, 3, 14]-=-. In contrast, in this paper we report upon a graph-based approach to such an integration. Our use of graphs has two key advantages : firstly, graphs are formally defined, well-understood structures; ... |

28 |
Non-well-founded sets. Center for the Study of Language and Information
- Aczel
- 1988
(Show Context)
Citation Context ...niverse of well-founded sets since hypernode equations may be cyclicly defined (for example, the equations defining P1 and P2 above). However, we can appeal to Aczel's theory of non-well-founded sets =-=[4]-=- to solve hypernode repositories. Nonwell -founded sets subsume well-founded sets by including circular sets i.e. sets that may contain themselves. It is shown in [4] that a set of set-defining equati... |

28 |
Untyped sets, inventions, and computable queries
- Hull, Su
- 1989
(Show Context)
Citation Context ...in all hypernode repositories which are well-typed with respect to TR. We define an update to be a partial recursive mapping from inst(TR) to inst(TR) that is C-generic. Cgenericity was introduced in =-=[21]-=- and intuitively means that, apart from a set of distinguished constants C (which may be the empty set), only the structure of a database is relevant to an update, not the values of the constants in t... |

18 |
Formal Models for Object Oriented Databases, in Deductive and ObjectOriented
- Beeri
- 1990
(Show Context)
Citation Context ...Phrases : Nested graph, complex object, types, rule-based query and update language, object store. 2 1. INTRODUCTION Recent database research has focussed on deductive [7, 14, 26] and object-oriented =-=[5, 22]-=- databases. Deductive databases extend the relational data model with rule-based computation. Rules enable the derivation of further, intentional, tuples from the stored, extensional, tuples. These de... |

14 |
A transient hypergraph-based model for data access
- WATTERS, A
- 1990
(Show Context)
Citation Context |

13 |
The hypernode model and its associated query language
- Levene, Poulovassilis
- 1990
(Show Context)
Citation Context ...ance is also supported naturally by nested graph structures (in that paper, we used nested hypergraphs but our treatment is equally applicable to the simpler nested graphs of the Hypernode Model). In =-=[24]-=- we also showed how methods can be supported as parametrised Hyperlog programs. The Hypernode Model supports the main features of Hypertext databases : Strings of arbitrary length are supported as a p... |

11 |
RL: Three principles of representation for semantic networks
- Griffith
- 1982
(Show Context)
Citation Context ...ed, extensional, tuples. These derived tuples can be used purely for querying purposes or can be inserted into the database. Conversely, object-oriented databases start off with a semantic data model =-=[16, 20, 31]-=-, which typically supports object identity, inheritance and complex objects, and extend it with features such as methods and encapsulation from object-oriented programming [32, 37]. Thus, deductive an... |

10 |
An object-oriented data model formalised through hypergraphs
- Levene, Poulovassilis
- 1991
(Show Context)
Citation Context |

7 |
Spaccapietra: Complex Objects Modeling: An EntityRelationship Approach
- Parent, Spaccapietra
- 1989
(Show Context)
Citation Context ...ed in conjunction with a number of conventional data models, for example the hierarchical and network models [35], the entity-relationship model [9] and a recent extension thereof for complex objects =-=[27]-=-, and various semantic data models [16, 20, 31]. Graphs or hypergraphs [6] have also been used more recently in [12, 17, 23, 25, 33, 36] as a data modelling tool in their own right. We give a comparis... |

4 |
A storage manager for the hypernode model
- Tuv, Poulovassilis, et al.
- 1992
(Show Context)
Citation Context ...(N i ,E i ), nsN i , (iii) given a label, G, return the set of labels {G 1 , ..., G r } such that for each equation G i = (N i ,E i ), GsN i . A detailed description of the Storage Manager appears in =-=[34]-=-. Briefly, the Storage Manager supports a number of object stores, each object store containing graphs of one type. Two object stores are reserved for the storage of types and programs. Associated wit... |

1 |
A hypertext database implemented using the Hypernode Model
- Dearden
- 1990
(Show Context)
Citation Context ...t a primitive node) : we initialise the previous contents of CUR_DOWN and use the rule 26 CUR_DOWN = ({Y,none ANY },)sCUR_NODE = ({X},), X = ({Y},) Browsing using Hyperlog was investigated further in =-=[13]-=-. In particular, it was shown that Hyperlog can support the declarative querying of the content and structure of a Hypertext database. This database was constructed by associating hypernodes with frag... |

1 |
Gucht D.V. A graph-oriented object database model
- Gyssens, Paredaens, et al.
- 1990
(Show Context)
Citation Context |