Rodney William Topor

Griffith University · School of Information and Communication Technology (ICT)

Ontology engineering and maintenance require (semi-)automated ontology change operations. Intensive research has been conducted on TBox and ABox changes in description logics (DLs), and various change operators have been proposed in the literature. Existing operators largely fall into two categories: syntaxbased and model-based.While each approach...

Forgetting is an important tool for reducing ontologies by eliminating some redundant concepts and roles while preserving sound and complete reasoning. Attempts have previously been made to address the problem of forgetting in relatively simple description logics (DLs), such as DL-Lite and extended . However, the issue of forgetting for ontologies...

In this study, we investigate and present a new index structure, Triangular Decomposition Tree (TD-tree), which can efficiently store and query temporal data in modern database applications. TD-tree is based on spatial representation of interval data and a recursive triangular decomposition of this space. A bounded number of intervals are stored in...

The need for efficient access and management of time dependent data in modern database applications is well recognised and researched. Existing access methods are mostly derived from the family of spatial R-tree indexing techniques. These techniques are particularly not suitable to handle data involving open ended intervals, which are common in tem...

Revising knowledge bases (KBs) in description logics (DLs) in a syntax-independent manner is an important and nontrivial problem for ontology management and DL communities. Several attempts have been made to adapt classical modelbased belief revision/update techniques to DLs, but they are restricted in several ways. In particular, they rarely inves...

In this paper, we propose two new approaches to forgetting for [Ascr ][Lscr ][Cscr ] based on the well-known tableau algorithm. The first approach computes the result of forgetting by rolling up tableaux, and also provides a decision algorithm for the existence of forgetting in [Ascr ][Lscr ][Cscr ]. When the result of forgetting does not exist, we...

Revising knowledge bases (KBs) in description logics (DLs) in a syntax-independent manner is an important, nontrivial problem for the ontology management and DL communities. Several attempts have been made to adapt classical modelbased belief revision and update techniques to DLs, but they are restricted in several ways. In particular, they do not...

Temporal and spatio-temporal data are present in many modern application systems, including monitoring moving objects. Such systems produce enormous volume of data, and therefore efficient indexing method is crucial. In this paper, we investigate and present a new concept based on virtual index structure, which can efficiently query such data. Conc...

Revising knowledge bases (KBs) in description logics (DLs) in a syntax-independent manner is an important, nontrivial problem for the ontology management and DL communities. Several attempts have been made to adapt classical model-based belief revision and update techniques to DLs, but they are restricted in several ways. In particular, they do not...

To support the reuse and combination of ontologies in Semantic Web applications, it is often necessary to obtain smaller ontologies from existing larger ontologies. In particular, applications may require the omission of certain terms, e. g., concept names and role names, from an ontology. However, the task of omitting terms from an ontology is cha...

The notion of uniform interpolation for description logic ALC\mathcal{ALC} has been introduced in [9]. In this paper, we reformulate the uniform interpolation for ALC\mathcal{ALC} from the angle of forgetting and show that it satisfies all desired properties of forgetting. Then we introduce an algorithm for computing the result of forgetting in con...

Forgetting is an important tool for reducing ontologies by eliminating some concepts and roles while preserving sound and complete reasoning. Attempts have previously been made to address the problem of forgetting in relatively simple description logics (DLs) such as DL-Lite and extended \({\mathcal {EL}}\). The ontologies used in these attempts we...

We address the revision problem for knowledge bases (KBs) in Description Logics (DLs). This problem has received much attention in the ontology management and DL communities, but the existing proposals are restricted in several ways. In this paper we develop a formal framework for revision of DL-Lite KBs, using techniques that are analogous to thos...

To support the reuse and combination of ontologies in Semantic Web applications, it is often necessary to obtain smaller ontologies from existing larger ontologies. In particular, applications may require the omission of many terms, e.g., concept names and role names, from an ontology. However, the task of omit- ting terms from an ontology is chall...

With the increasing number of ontologies available on the web, the problem of merging ontologies from different sources to interoperate applications becomes important. This paper presents a novel approach for merging of light-weight ontologies based on answer set programming (ASP) and linguistic background knowledge. ASP provides a declarative exec...

With the increasing number of ontologies available on the web, the problem of merging ontologies from different sources to interoperate applications becomes important. This paper presents a novel approach for merging of light-weight ontologies based on answer set programming (ASP) and linguistic background knowledge. ASP provides a declarative exec...

Several proposals have been put forward to support distributed agent cooperation in the Semantic Web, by allowing concepts and roles in one ontology be reused in another ontology. In general, these proposals reduce the autonomy of each ontology by defining the semantics of the ontology to depend on the semantics of the other ontologies. We propose...

In this paper, we propose a new heuristic algorithm called the QIBC algorithm that improves the privacy of sensitive knowledge (as itemsets) by blocking more inference channels. We show that the existing sanitizing algorithms for such task have fundamental drawbacks. We show that previous methods remove more knowledge than necessary for unjustified...

We extend the concept of domain independence from queries and databases to disjunctive databases. Informally, a domain independent disjunctive database is one for which the set of correct answers to any domain independent query is independent of the domains of variables in the database statements. We prove that every allowed stratified disjunctive...

The language of dl-programs is a latest effort in developing an expressive representation for Web-based ontologies. It allows to build answer set programming (ASP) on top of description logic and thus some attractive features of ASP can be employed in the design of the Semantic Web architecture. In this paper we first generalize dl-programs by allo...

The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach for finding contained rewritings of unions of conjunctive queries with arbitrary built-in predicates. Our approach is based on an improved method for testing conjunctive q...

We study the design issues of data-centric XML documents where (1) there are no mixed contents, i.e., each element may have some subelements and attributes, or it may have a single value in the form of a character string, but not a mixture of strings and subelements and/or attributes, (2) the ordering of subelements is of no significance. We provid...

Mining transaction databases for association rules usually generates a large number of rules, most of which are unnecessary when used for subsequent prediction. In this paper we define a rule set for a given transaction database that is much smaller than the association rule set but makes the same predictions as the association rule set by the conf...

Health informatics is increasingly of interest due to its potential in making our health care systems safer. The term 'health or medical informatics' refers to the “application of information technologies to optimise information management within all aspects of health care delivery". A research project has been initiated to explore the effectivenes...

We define an optimal class association rule set to be the minimum rule set with the same predictive power of the complete class association rule set. Using this rule set instead of the complete class association rule set we can avoid redundant computation that would otherwise be required for mining predictive association rules and hence improve the...

This paper presents an efficient linear-time sequential algorithm for constructing Hamiltonian paths between two given vertices in meshes with horizontal size m and vertical size n. The algorithm first partitions the given mesh into a number of submeshes in constant steps, and then constructs a Hamiltonian cycle or path in each submesh and combines...

We present four efficient parallel algorithms for computing a nonequijoin, called range-join, of two relations on N-dimensional mesh-connected computers. Range-joins of relations R and S are an important generalization of conventional equijoins and band-joins and are solved by permutation-based approaches in all proposed algorithms. In general, aft...

The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach for finding contained rewritings of unions of conjunctive queries with arbitrary built-in predicates. Our approach is based on an improved method for testing conjunctive q...

The problem of rewriting queries using views has important applications in data integration, query optimization, and physical data independence maintenance. Previous researchers have proposed rewriting algorithms for queries and views that are Datalog programs or conjunctive queries with arithmetic comparisons such as x < y and y 10. We present a m...

We study the problem of computing classification rule sets from relational databases so that accurate predictions can be made on test data with missing attribute values. Traditional classifiers perform badly when test data are not as complete as the training data because they tailor a training database too much. We introduce the concept of one rule...

Mining transaction databases for association rules usually generates a large number of rules, most of which are unnecessary when used for subsequent prediction. In this paper we define a rule set for a given transaction database that is much smaller than the association rule set but makes the same predictions as the association rule set by the conf...

. In extended relational databases, queries and integrity constraints often contain interpreted variables and built-in relations. We extend previous work on semantic query containment for extended relational databases to handle disjunctive constrained tuple-generating dependencies (DCTGDs) which include almost all well-known classes of integrity co...

In this paper, we present two efficient parallel algorithms for computing a non-equijoin, range-join, of two relations an N-dimensional mesh-connected computers. The proposed algorithms uses the data-shifting approach to effectively permute every sorted subset of relation S to each processor in turn recursively in dimensions from low to high, where...

We define an optimal class association rule set to be the minimum rule set with the same predictive power of the complete class association rule set. Using this rule set instead of the complete class association rule set we can avoid redundant computation that would otherwise be required for mining predictive association rules and hence improve the...

Mining transaction databases for association rules usually generates a large number of rules, most of which are unnecessary when used for subsequent prediction. In this paper we define a rule set for a given transaction database that is much smaller than the association rule set but makes the same predictions as the association rule set by the conf...

Mining quantitative association rules is an important topic of data mining since most real world databases have both numerical and categorical attributes. Typical solutions involve partitioning each numerical attribute into a set of disjoint intervals, interpreting each interval as an item, and applying standard boolean association rule mining. Com...

We present global and local algorithms for generating traversals of arbitrary trees with the property that the maximum number of edges between successive nodes in any traversal is three, and that this is the best possible result. We describe the application of such traversals to parallel computing. Keywords Algorithms, concurrent tree traversal, in...

We describe the relationship between inheritance with overriding in an object-oriented database language, Gulog, and negation. We present a translation from Gulog programs to Datalog programs with negation and show that evaluating queries in the translation yields correct answers with respect to the original program. Keywords: object-oriented, inhe...

. In object-oriented languages, multiple inheritance can cause ambiguities when methods of the same name are inherited from more than one superclass of a given class. In C++, qualifiers can be used to explicitly state which method should be inherited. We describe a mathematical foundation for an object-oriented language that uses qualifiers or role...

We present a simple model for deductive objectoriented systems with inheritance and overriding. In this model we define a declarative semantics based on preferred minimal models, we present bottom-up and top-down procedures for query evaluation, and we note that these procedures are sound with respect to the declarative semantics. 1 Introduction Th...

This paper proposes a parallel algorithm to compute the range-join of two relations on N -dimensional torus computers. The algorithm efficiently permutes all subsets of one relation to each processor in turn, where they are joined with the subset of the other relation at that processor using a local range-join algorithm. The analysis shows that the...

This paper presents an efficient parallel algorithm for computing the mutual range-join of N sets of data on shared-nothing hypercube computers. The algorithm repeatedly joins each set to the join result of the preceding sets. Each join is performed on all processors of the hypercube in parallel. The algorithm efficiently partitions the first set e...

this paper, we analyse and compare the performance of two extreme forms of pipeline parallelism, assuming a limited amount of main memory available on a distributed shared memory computer. We show how to construct an intermediate form of pipeline parallelism that fully exploits the available main memory to achieve better performance than either ext...

We present a simple algorithm for constructing Hamiltonian cycles on trees together with additional edges between leaves, compute the number of such additional edges required for complete k-ary trees of given depth, show this number is minimal over all Hamiltonian cycles, and present an algorithm that determines the successor of each node in the cy...

This paper presents an improved parallel hash-based join algorithm on a hypercube computer in the presence of double skew. We describe a load balancing technique to evenly distribute both join relations across all processors in order to deal with double skew effectively. Moreover, we propose a permutation join method which reduces main memory requi...

This paper presents an efficient parallel algorithm for computing the mutual range-join of N sets of numbers on shared-nothing hypercube computers. The algorithm iteratively joins each set to the mutual range-join of the preceding sets. Each join is performed on all processors of the hypercube in parallel. The algorithm uses a global sorting method...

This paper proposes three efficient parallel algorithms for computing the range-join of two relations on a two-dimensional n Theta m mesh-connected computer, where n and m are the numbers of the rows and columns respectively. The proposed algorithms sort all subsets of both relations, and then efficiently permute all sorted subsets of one relation...

This paper presents an efficient parallel algorithm for computing the mutual range-join of N sets of numbers on shared-nothing hypercube computers. The algorithm iteratively joins each set to the mutual range-join of the preceding sets. Each join is performed on all processors of the hypercube in parallel. The algorithm uses a global sorting method...

We extend our previous mathematical foundation for a deductive object-oriented language called Gulog to include arithmetic and aggregate operators. We describe the semantics of the extended language and present a corresponding query evaluation procedure.

This paper proposes three efficient parallel algorithms for computing the range-join of two relations on two-dimensional n x m mesh-connected computers, where n and m are the numbers of the rows and columns respectively. After sorting all subsets of both relations, all proposed algorithms permute all sorted subsets of one relation to each processor...

We consider the problem of repeatedly evaluating the same (computationally expensive) query to a database that is being updated between successive query requests. In this situation, it should be possible to use the difference between successive database states and the answer to the query in one state to reduce the cost of evaluating the query in th...

We consider the problem of repeatedly evaluating the same (computationally expensive) query to a database that is being updated between successive query requests. In this situation, it should be possible to use the difference between successive database states and the answer to the query in one state to reduce the cost of evaluating the query in th...

We consider the theory of database queries on a relational data model that includes a set of fixed relations used to model arithmetic comparisons and operations. We describe how to extend several natural query languages such as first-order logic, Datalog, and stratified Datalog to apply to databases in this model, and show that their relative expre...

Object-oriented database systems provide expressive power and the potential for reuse, extensibility and modifiability. Relational and deductive database systems provide a simple logical semantics and the ability to represent complex derived information. Many proposals have been made for database systems that offer both sets of features, and some c...

We present declarative and procedural semantics for a deductive object-oriented language, Gulog. The declarative semantics is based on preferred minimal models. We describe both bottom-up and top-down query evaluation procedures and show that they are sound with respect to the declarative semantics. The results contribute to our understanding of th...

This paper proposes a parallel algorithm to compute the range-join of two relations on N-dimensional torus computers. The algorithm efficiently permutes all subsets of one relation to each processor in turn, where they are joined with the subset of the other relation at that processor using a local range-join algorithm. The analysis shows that the...

We present a proposed query language for extended entity relationship schemas. The language improves on previous proposals by using only concepts explicitly in a given schema. It includes quantiers and aggregates to allow complex queries to be expressed, and it allows derived subtypes, attributes and relation- ships to be dened and used in queries....

We consider the addition of set-valued methods and multiple inheritance to a simple deductive object-oriented language we defined and studied previously. We show how the previously defined declarative semantics can be extended to provide a natural semantics for inheritance and overriding in this more general setting, and similarly extend our previo...

We consider the theory of database queries on a relational data model that includes a set of fixed relations used to model arithmetic comparisons and operations. We describe how to extend several natural query languages such as first-order logic, Datalog, and stratified Datalog to to apply to databases in this model, and show that their relative ex...

We present a procedure for deriving the weakest precondition for a data- base update and an integrity constraint. We show how to simplify the weak- est precondition to produce a condition to be evaluated before the update is performed. This provides an ecient means to ensure that database updates maintain integrity constraints.

Not all queries in relational calculus can be answered sensibly when disjunction, negation, and universal quantification are allowed. The class of relation calculus queries or formulas that have sensible answers is called the domain independent class which is known to be undecidable. Subsequent research has focused on identifying large decidable su...

Not all queries in relational calculus can be answered sensibly when disjunction, negation, and universal quantification are allowed. The class of relation calculus queries or formulas that have sensible answers is called the domain independent class which is known to be undecidable. Subsequent research has focused on identifying large decidable su...

We introduce and study the concept of domain independence to characterize the class of reasonable databases. A domain independent database is one for which the set of correct answers to an atomic query is independent of the domains of variables in the database statements. In particular, we prove that every “allowed” stratified database is domain in...

We propose criteria that any rule for inferring negative information from disjunctive databases should satisfy, and examine existing rules from this viewpoint. We then present a new inference rule, the ‘disjunctive database rule’ (DDR), and compare it to the existing rules with respect to the criteria. In particular, the DDR is equivalent to the CW...

We prove the correctness of a simplification method for checking static integrity constraints in stratified deductive databases.

This paper studies the class of deductive databases for which the result of query evaluation is independent of the domains of variables in database clauses. We first describe the class of domain-independent formulas in proof-theoretic terms. A new recursive subclass of ‘allowed’ formulas is defined and its properties studied. It is shown that every...

Not all queries in relational calculus can be answered “sensibly” once disjunction, negation, and universal quantification are allowed. The class of relational calculus queries, or formulas, that have “sensible” answers is called the domain independent class, which is known to be undecidable. Subsequent research has focused on identifying large dec...

This paper is the third in a series providing a theoretical basis for deductive database systems. A deductive database consists of closed typed first order logic formulas of the form A ← W, where A is an atom and W is a typed first order formula. A typed first order formula can be used as a query, and a closed typed first order formula can be used...

This paper provides a theoritical basis for deductive database systems. A deductive database consists of closed typed first order logic formulas of the form A ← W, where A is an atom and W is a typed first order formula. A typed first order formula can be used as a query, and a closed typed first order formula can be used as an integrity constraint...

This paper introduces extended programs and extended goals for logic programming. A clause in an extended program can have an arbitrary first-order formula as its body. Similarly, an extended goal can have an arbitrary first-order formula as its body. The main results of the paper are the soundness of the negation as failure rule and SLDNF-resoluti...

A simple derivation of a general solution to the problem of detecting the termination of a distributed computation is presented.

Previous algorithms presented to solve the eight queens problem have generated the set of all solutions. Many of these solutions are identical after applying sequences of rotations and reflections. In this paper we present a simple, clear, efficient algorithm to generate a set of fundamental (or distinct) solutions to the problem.

Several functional programs for generating permutations represented as linear linked lists are presented. Exact formulas for the storage used by some of these programs are derived and compared with the theoretical lower bound. Two different programs are shown to be optimal with respect to this measure. Problems considered include generation of all...

Parameter passing mechanisms are developed for optional, repeatable, and varying type parameters. For optional parameters, a programmer-defined default value is passed when the actual parameter is not present; in addition, the called procedure may determine ...

This paper presents a relatively simple proof of a nontrivial algorithm for marking all the nodes of a list structure. The proof separates properties of the algorithm from properties of the data on which it operates and is a significant application of the method of intermittent assertions.

This thesis is concerned with ways of proving the correctness of computer programs. The first part of the thesis presents a new method for doing this. The method, called continuation induction, is based on the ideas of symbolic execution, the description of a given program by a virtual program, and the demonstration that these two programs are equi...

We consider the problem of repeatedly evaluating the same (computationally expensive) query to a database that is being updated between successive query requests. In this situation, it should be possible to use the difference between successive database states and the answer to the query in one state to reduce the cost of evaluating the query in th...

No Yes

We propose a framework for heterogeneous multi-context systems, in which a special kind of semantic/implicit bridge rules are introduced. Traditional bridge rules in heterogeneous multi-context systems may make the syntax and the semantics of a context more complex, e.g., in the approach of [3] an agent may have to facing a context composed by a de...

Forgetting is a useful tool for tailoring ontologies by reducing the number of concepts and roles, while preserving sound and complete reasoning. Some attempts have been made to address the problem of forgetting in some relatively simple description logics (DLs) such as DL-Lite and extended EL . Ontologies in those works are mostly expressed as TBo...