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Displaying 1-39 out of 39 total
An interview with Melanie Mitchell: Melanie Mitchell on complexity
Found in: Ubiquity
By Peter J. Ubiquity Staff, Richard T. Snodgrass, Peter J. Ubiquity Staff, Peter J. Ubiquity Staff, Richard T. Snodgrass, Richard T. Snodgrass
Issue Date:April 2011
pp. 1-6
Melanie Mitchell, a Professor of Computer Science at Portland State University and an External Professor at the Santa Fe Institute, has written a compelling and engaging book entitled Complexity: A Guided Tour, published just last year by Oxford University...
     
Valid-Time Indeterminacy in Temporal Relational Databases: Semantics and Representations
Found in: IEEE Transactions on Knowledge and Data Engineering
By Luca Anselma,Paolo Terenziani,Richard T. Snodgrass
Issue Date:December 2013
pp. 2880-2894
Valid-time indeterminacy is "don't know when" indeterminacy, coping with cases in which one does not exactly know when a fact holds in the modeled reality. In this paper, we first propose a reference representation (data model and algebra) in whi...
 
Temporal Support for Persistent Stored Modules
Found in: Data Engineering, International Conference on
By Richard T. Snodgrass,Dengfeng Gao,Rui Zhang,Stephen W. Thomas
Issue Date:April 2012
pp. 114-125
We show how to extend temporal support of SQL to the Turing-complete portion of SQL, that of persistent stored modules (PSM). Our approach requires minor new syntax beyond that already in SQL/Temporal to define and to invoke PSM routines, thereby extending...
 
A Foundation for Conventional and Temporal Query Optimization Addressing Duplicates and Ordering
Found in: IEEE Transactions on Knowledge and Data Engineering
By Giedrius Slivinskas, Christian S. Jensen, Richard T. Snodgrass
Issue Date:January 2001
pp. 21-49
<p><b>Abstract</b>—Most real-world databases contain substantial amounts of time-referenced, or temporal, data. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in tempo...
 
Query Plans for Conventional and Temporal Queries Involving Duplicates and Ordering
Found in: Data Engineering, International Conference on
By Giedrius Slivinskas, Christian S. Jensen, Richard T. Snodgrass
Issue Date:March 2000
pp. 547
No summary available.
 
Extending Existing Dependency Theory to Temporal Databases
Found in: IEEE Transactions on Knowledge and Data Engineering
By Christian S. Jensen, Richard T. Snodgrass, Michael D. Soo
Issue Date:August 1996
pp. 563-582
<p><b>Abstract</b>—Normal forms play a central role in the design of relational databases. Several normal forms for temporal relational databases have been proposed. These definitions are particular to specific temporal data models, which...
 
An Architecture for Regulatory Compliant Database Management
Found in: Data Engineering, International Conference on
By Soumyadeb Mitra, Marianne Winslett, Richard T. Snodgrass, Shashank Yaduvanshi, Sumedh Ambokar
Issue Date:April 2009
pp. 162-173
Spurred by financial scandals and privacy concerns, governments worldwide have moved to ensure confidence in digital records by regulating their retention and deletion. These requirements have led to a huge market for compliance storage servers, which ensu...
 
Efficient Sequenced Temporal Integrity Checking
Found in: Data Engineering, International Conference on
By Wei Li, Richard T. Snodgrass, Shiyan Deng, Aravindan Kasthurirangany, Vineel K. Gattu
Issue Date:April 2001
pp. 0131
Abstract: Primary key and referential integrity are the most widely used integrity constraints in relational databases. Each has a sequenced analogue in temporal databases, in which the constraint must apply independently at every point in time. In this pa...
 
Sequenced Subset Operators: Definition and Implementation
Found in: Data Engineering, International Conference on
By Joseph Dunn, Sean Davey, Anne Descour, Richard T. Snodgrass
Issue Date:March 2002
pp. 0081
Difference, intersection, semi-join and anti-semi-join may be considered binary subset operators, in that they all return a subset of their left-hand argument. These operators are useful for implementing SQL's EXCEPT, INTERSECT, NOT IN and NOT EXISTS, dist...
 
Computer science can use more science
Found in: Communications of the ACM
By Clayton T. Morrison, Richard T. Snodgrass, Richard T. Snodgrass
Issue Date:June 2011
pp. 36-38
Software developers should use empirical methods to analyze their designs to predict how working systems will behave.
     
The Tiled Bitmap Forensic Analysis Algorithm
Found in: IEEE Transactions on Knowledge and Data Engineering
By Kyriacos E. Pavlou, Richard T. Snodgrass
Issue Date:April 2010
pp. 590-601
Tampering of a database can be detected through the use of cryptographically strong hash functions. Subsequently, applied forensic analysis algorithms can help determine when, what, and perhaps ultimately who and why. This paper presents a novel forensic a...
 
Parallel Algorithms for Computing Temporal Aggregates
Found in: Data Engineering, International Conference on
By Jose Alvin G. Gendrano, Bruce C. Huang, Jim M. Rodrigue, Bongki Moon, Richard T. Snodgrass
Issue Date:March 1999
pp. 418
The ability to model the temporal dimension is essential to many applications. Furthermore, the rate of increase in database size and response time requirements has out-paced advancements in processor and mass storage technology, leading to the need for pa...
 
Valid-Time Indeterminacy in Temporal Relational Databases: A Family of Data Models
Found in: Temporal Representation and Reasoning, International Syposium on
By Luca Anselma, Paolo Terenziani, Richard T. Snodgrass
Issue Date:September 2010
pp. 139-145
Valid-time indeterminacy concerns not knowing exactly when a fact holds in the modeled reality. In this paper, we first propose a reference approach (data model and algebra) in which all possible temporal scenarios induced by valid-time indeterminacy can b...
 
Validating Quicksand: Schema Versioning in \tauXSchema
Found in: Data Engineering Workshops, 22nd International Conference on
By Curtis Dyreson, Richard T. Snodgrass, Faiz Currim, Sabah Currim, Shailesh Joshi
Issue Date:April 2006
pp. 82
The W3C XML Schema recommendation defines the structure and data types for XML documents, but lacks explicit support for time-varying XML documents or for a time-varying schema. In previous work we introduced \tauXSchema which is an infrastructure and suit...
 
Spatiotemporal Aggregate Computation: A Survey
Found in: IEEE Transactions on Knowledge and Data Engineering
By Inés Fernando Vega López, Richard T. Snodgrass, Bongki Moon
Issue Date:February 2005
pp. 271-286
Spatiotemporal databases are becoming increasingly more common. Typically, applications modeling spatiotemporal objects need to process vast amounts of data. In such cases, generating aggregate information from the data set is more useful than individually...
 
Forensic analysis of database tampering
Found in: ACM Transactions on Database Systems (TODS)
By Kyriacos E. Pavlou, Richard T. Snodgrass, Richard T. Snodgrass
Issue Date:November 2008
pp. 1-47
Regulations and societal expectations have recently expressed the need to mediate access to valuable databases, even by insiders. One approach is tamper detection via cryptographic hashing. This article shows how to determine when the tampering occurred, w...
     
Adding Temporal Constraints to XML Schema
Found in: IEEE Transactions on Knowledge and Data Engineering
By Faiz A. Currim,Sabah A. Currim,Curtis E. Dyreson,Richard T. Snodgrass,Stephen W. Thomas,Rui Zhang
Issue Date:August 2012
pp. 1361-1377
HASH(0x457fbbc)
 
Using the Lock Manager to Choose Timestamps
Found in: Database Engineering and Applications Symposium, International
By David Lomet, Richard T. Snodgrass, Christian S. Jensen
Issue Date:July 2005
pp. 357-368
Our goal is to support transaction-time functionality that enables the coexistence of ordinary, non-temporal tables with transaction-time tables. In such a system, each transaction updating a transaction-time or snapshot table must include a timestamp for ...
 
Efficiently Supporting Temporal Granularities
Found in: IEEE Transactions on Knowledge and Data Engineering
By Curtis E. Dyreson, William S. Evans, Hong Lin, Richard T. Snodgrass
Issue Date:July 2000
pp. 568-587
<p><b>Abstract</b>—<it>Granularity</it> is an integral feature of temporal data. For instance, a person's age is commonly given to the granularity of <it>years</it> and the time of their next airline flight to the ...
 
Capturing Telic/Atelic Temporal Data Semantics: Generalizing Conventional Conceptual Models
Found in: IEEE Transactions on Knowledge and Data Engineering
By Vijay Khatri,Sudha Ram,Richard T. Snodgrass,Paolo Terenziani
Issue Date:March 2014
pp. 528-548
Time provides context for all our experiences, cognition, and coordinated collective action. Prior research in linguistics, artificial intelligence, and temporal databases suggests the need to differentiate between temporal facts with goal-related semantic...
 
Temporal Implications of Database Information Accountability
Found in: 2012 19th International Symposium on Temporal Representation and Reasoning (TIME)
By Kyriacos E. Pavlou,Richard T. Snodgrass
Issue Date:September 2012
pp. 125-132
Information restriction controls access and renders records immutable, information accountability requires data transparency to easily and efficiently determine when a particular use is appropriate. Information accountability in the context of relational d...
 
Application of Micro-specialization to Query Evaluation Operators
Found in: 2012 IEEE International Conference on Data Engineering Workshops (ICDEW)
By Rui Zhang,Richard T. Snodgrass,Saumya Debray
Issue Date:April 2012
pp. 315-321
Relational database management systems support a wide variety of data types and operations. Such generality involves much branch condition checking, which introduces inefficiency within the query evaluation loop. We previously introduced micro-specializati...
 
Achieving Database Information Accountability in the Cloud
Found in: 2012 IEEE International Conference on Data Engineering Workshops (ICDEW)
By Kyriacos E. Pavlou,Richard T. Snodgrass
Issue Date:April 2012
pp. 147-150
Regulations and societal expectations have recently emphasized the need to mediate access to valuable databases. Fraud occurs when a person (mostly an insider) tampers illegally with a database. Data owners would like to be assured that such tampering has ...
 
DRAGOON: An Information Accountability System for High-Performance Databases
Found in: Data Engineering, International Conference on
By Kyriacos E. Pavlou,Richard T. Snodgrass
Issue Date:April 2012
pp. 1329-1332
Regulations and societal expectations have recently emphasized the need to mediate access to valuable databases, even access by insiders. Fraud occurs when a person, often an insider, tries to hide illegal activity. Companies would like to be assured that ...
 
Micro-Specialization in DBMSes
Found in: Data Engineering, International Conference on
By Rui Zhang,Richard T. Snodgrass,Saumya Debray
Issue Date:April 2012
pp. 690-701
Relational database management systems are general in the sense that they can handle arbitrary schemas, queries, and modifications, this generality is implemented using runtime metadata lookups and tests that ensure that control is channelled to the approp...
 
Towards a Science of Temporal Databases
Found in: Temporal Representation and Reasoning, International Syposium on
By Richard T. Snodgrass
Issue Date:June 2007
pp. 6-7
Computer science has long been considered to emphasize three distinct perspectives: mathematics, science, and engineering. While the database field has some very strong mathematical and engineering work, the scientific perspective has been much less promin...
   
Augmenting a Conceptual Model with Geospatiotemporal Annotations
Found in: IEEE Transactions on Knowledge and Data Engineering
By Vijay Khatri, Sudha Ram, Richard T. Snodgrass
Issue Date:November 2004
pp. 1324-1338
While many real-world applications need to organize data based on space (e.g., geology, geomarketing, environmental modeling) and/or time (e.g., accounting, inventory management, personnel management), existing conventional conceptual models do not provide...
 
Guest Editors' Introduction to Special Section On Temporal and Real-Time Databases
Found in: IEEE Transactions on Knowledge and Data Engineering
By Gultekin Ozsoyoglu, Richard T. Snodgrass
Issue Date:August 1995
pp. 511-512
No summary available.
 
On experimental algorithmics: an interview with Catherine McGeoch and Bernard Moret
Found in: Ubiquity
By Richard T. Snodgrass
Issue Date:December 2013
pp. 1-14
How does technology change learning and teaching in formal and informal education?
     
Generalizing database forensics
Found in: ACM Transactions on Database Systems (TODS)
By Kyriacos E. Pavlou, Richard T. Snodgrass
Issue Date:June 2013
pp. 1-43
In this article we present refinements on previously proposed approaches to forensic analysis of database tampering. We significantly generalize the basic structure of these algorithms to admit new characterizations of the “where” axis of the c...
     
On experimental algorithmics: an interview with Catherine McGeoch and Bernard Moret
Found in: Ubiquity
By Richard T. Snodgrass
Issue Date:August 2011
pp. 1-14
Computer science is often divided into two camps, systems and theory, but of course the reality is more complicated and more interesting than that. One example is the area of "experimental algorithmics," also termed "empirical algorithmics." This fascinati...
     
Forensic analysis of database tampering
Found in: Proceedings of the 2006 ACM SIGMOD international conference on Management of data (SIGMOD '06)
By Kyriacos Pavlou, Richard T. Snodgrass
Issue Date:June 2006
pp. 109-120
Mechanisms now exist that detect tampering of a database, through the use of cryptographically-strong hash functions. This paper addresses the next problem, that of determining who, when, and what, by providing a systematic means of performing forensic ana...
     
Skew handling techniques in sort-merge join
Found in: Proceedings of the 2002 ACM SIGMOD international conference on Management of data (SIGMOD '02)
By Dengfeng Gao, Richard T. Snodgrass, Wei Li
Issue Date:June 2002
pp. 169-180
Joins are among the most frequently executed operations. Several fast join algorithms have been developed and extensively studied; these can be categorized as sort-merge, hash-based, and index-based algorithms. While all three types of algorithms exhibit e...
     
Adaptable query optimization and evaluation in temporal middleware
Found in: Proceedings of the 2001 ACM SIGMOD international conference on Management of data (SIGMOD '01)
By Christian S. Jensen, Giedrius Slivinskas, Richard T. Snodgrass
Issue Date:May 2001
pp. 256-266
Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built-in temporal support in the DBMS. To achieve this, temporal query optimiza...
     
Temporal statement modifiers
Found in: ACM Transactions on Database Systems (TODS)
By Christian S. Jensen, Michael H. Bohlen, Richard T. Snodgrass
Issue Date:March 1988
pp. 407-456
A wide range of database applications manage time-varying data. Many temporal query languages have been proposed, each one the result of many carefully made yet subtly interacting design decisions. In this article we advocate a different approach to articu...
     
Supporting valid-time indeterminacy
Found in: ACM Transactions on Database Systems (TODS)
By Curtis E. Dyreson, Richard T. Snodgrass
Issue Date:March 1988
pp. 1-57
In valid-time indeterminacy it is known that an event stored in a database did in fact occur, but it is not known exactly when. In this paper we extend the SQL data model and query language to support valid-time indeterminacy. We represent the occurrence t...
     
The inefficiency of misalignment
Found in: ACM Computing Surveys (CSUR)
By Richard T. Snodgrass
Issue Date:March 1988
pp. 89-es
Floating-point divide and square-root operations are essential to many scientific and engineering applications, and are required in all computer systems that support the IEEE floating-point standard. Yet many current microprocessors provide only weak supp...
     
Evaluation of relational algebras incorporating the time dimension in databases
Found in: ACM Computing Surveys (CSUR)
By L. Edwin McKenzie, Richard T. Snodgrass
Issue Date:March 1988
pp. 501-543
At high data transmission rates, the packet transmission time of a local area network (LAN) could become comparable to or less than the medium propagation delay. The performance of many LAN schemes degrades rapidly when the packet transmission time becomes...
     
Rights and responsibilities in ACM publishing
Found in: Communications of the ACM
By Richard T. Snodgrass
Issue Date:January 1988
pp. 97-101
Progress on ACM's Becoming the Preferred Publisher
     
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