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A Formal Context for Acyclic Join Dependencies [chapter]

Jaume Baixeries
2017 Lecture Notes in Computer Science  
Acyclic Join Dependencies (AJD) play a crucial role in database design and normalization.  ...  In this paper, we use Formal Concept Analysis (FCA) to characterize a set of AJDs that hold in a given dataset.  ...  Conclusions and Future Work We have presented a new formal context for acyclic join dependencies.  ... 
doi:10.1007/978-3-319-60438-1_55 fatcat:5nbac4nawnb3hn2q7xncjsgjfu

Pairwise-definable subdirect decompositions of general database schemata [chapter]

Stephen J. Hegner
1991 Lecture Notes in Computer Science  
context of any decomposition into a set of views. † Much of the research reported herein was performed while the author was visiting the Mathematics Department of the University of Oslo, Norway.  ...  In this paper, we show that the thrust of these results is not specific to the relational model, but rather applies in a much more general context in which schemata are just sets and views are defined  ...  We shall always regard a multivalued dependency as a join dependency on two projections; for our purposes, the multi- For valued dependency W → → V (with W ∩ V = ∅) on attribute set U is the join dependency  ... 
doi:10.1007/3-540-54009-1_18 fatcat:bselxpzfgfdxzmtcldx2pvzumq

Page 2130 of Mathematical Reviews Vol. , Issue 85e [page]

1985 Mathematical Reviews  
{For the entire collection see MR 85e:68002.} Hull, Richard (1-SCA-C) 85¢:68015 Acyclic join dependency and data base projections. J. Comput.  ...  To obtain these results, a new characterization of acyclic join dependency, based on ‘structured edge-trees’, is given.  ... 

Characterization of desirable properties of general database decompositions

Stephen J. Hegner
1993 Annals of Mathematics and Artificial Intelligence  
, and in turn equivalent to certain acyclicity characterizations of a hypergraph underlying the schema.  ...  Even if some of the technical terms specific to our presentation are not familiar, it should be possible to get the general idea of how fragile 0.1.1 is, relative to adding even a few functional dependencies  ...  He wishes to thank in particular the members of the Computational Linguistics Group for their kind hospitality during his stay there.  ... 
doi:10.1007/bf01556353 fatcat:z452whuvqvh2dlo4l56ogxy7n4

Acyclic database schemes (of various degrees): A painless introduction [chapter]

Ronald Fagin
1983 Lecture Notes in Computer Science  
Since multivalued dependencies are simple special cases of join dependencies, it is a desirable property of a join dependency for it to be equivalent to a set of multivalued dependencies.  ...  Two of these sections. namely Sections 6 and 7 (dealing with the formal definition of acyclicity and with join dependencies) are more technical, and may be skipped without real loss for many readers.  ...  Acknowledgment The author is grateful to Moshe Vardi for helpful comments.  ... 
doi:10.1007/3-540-12727-5_3 fatcat:ullpgmbb2nem5cdzkao52mywwy

Decomposition of Distributed Nonmonotonic Multi-Context Systems [chapter]

Seif El-Din Bairakdar, Minh Dao-Tran, Thomas Eiter, Michael Fink, Thomas Krennwallner
2010 Lecture Notes in Computer Science  
Multi-Context Systems (MCS) are formalisms that enable the interlinkage of single knowledge bases, called contexts, via bridge rules.  ...  It applies pruning techniques to get economically small representations of context dependencies.  ...  One formalism are Multi-Context Systems (MCS) consisting of several theories (the contexts) that are interlinked with bridge rules which allow to add knowledge to a context depending on knowledge in other  ... 
doi:10.1007/978-3-642-15675-5_5 fatcat:dbd3uglu5na5dd5qv35xsyqns4

Page 4803 of Mathematical Reviews Vol. , Issue 86j [page]

1986 Mathematical Reviews  
In this paper, we study this problem in the context of non-two- phase locking protocols which are defined for databases in which a directed acyclic graph structure is superimposed on the data items.  ...  We give a characterization for multilevel atomicity, in terms of the absence of cycles in a dependency relation among transaction steps. Some remarks are made concerning implementation.”  ... 

Realising Dead Path Elimination in BPMN

Matthias Weidlich, Alexander Grosskopf, Alistair Barros
2009 2009 IEEE Conference on Commerce and Enterprise Computing  
We provide a generic formal definition of DPE and discuss resulting control flow requirements independent of specific process description languages.  ...  Although this is straightforward for the majority of concepts, it is tricky for the full BPEL standard, partly due to the insufficiently specified BPMN execution semantics.  ...  The context is a set of guard conditions, which have to hold in order for the rule to apply.  ... 
doi:10.1109/cec.2009.32 dblp:conf/wecwis/WeidlichGB09 fatcat:qp5gdungl5cc3mxkvhwql57tzy

A New Semantics for the Inclusive Converging Gateway in Safe Processes [chapter]

Hagen Völzer
2010 Lecture Notes in Computer Science  
We propose a new semantics for the inclusive converging gateway (also known as Or-join).  ...  A key insight is that not all situations where two or more Or-joins seem to be mutually dependent (known as 'vicious circles') are necessarily symmetric.  ...  We would like to thank Alistair Barros and the other members of the BPMN 2.0 RFP taskforce, in particular Matthias Kloppmann and Stephen A.  ... 
doi:10.1007/978-3-642-15618-2_21 fatcat:rgsg3giewzfs7f2xzcjjtf7qea

Distributed Evaluation of Nonmonotonic Multi-context Systems

Minh Dao-Tran, Thomas Eiter, Michael Fink, Thomas Krennwallner
2015 The Journal of Artificial Intelligence Research  
Multi-context Systems (MCSs) are a formalism for systems consisting of knowledge bases (possibly heterogeneous and non-monotonic) that are interlinked via bridge rules, where the global system semantics  ...  While MCSs and related formalisms are inherently targeted for distributed set- tings, no truly distributed algorithms for their evaluation were available.  ...  Our approach, however, allows for cyclic dependency between contexts.  ... 
doi:10.1613/jair.4574 fatcat:p6xuouc3bja5tlwqscsx4fvtjm

Why is the snowflake schema a good data warehouse design?

Mark Levene, George Loizou
2003 Information Systems  
We then define a normal form for snowflake schemas which captures its intuitive meaning with respect to a set of functional and inclusion dependencies.  ...  We formalise the concept of a snowflake schema in terms of an acyclic database schema whose join tree satisfies certain structural properties.  ...  The authors would like to thank the referees for their constructive comments. We especially thank one of the referees who suggested the extension of snowflake schema detailed in Section 4.  ... 
doi:10.1016/s0306-4379(02)00021-2 fatcat:z6wsjg627fh5bcheb2am2f2v7u

Modelling contextuality by probabilistic programs with hypergraph semantics

Peter D. Bruza
2017 Theoretical Computer Science  
The use of hypergraphs opens the door for a theoretically succinct and efficient computational semantics sensitive to modelling both contextual and non-contextual phenomena.  ...  Each such context delivers a partial model of the phenomenon based on the associated experimental condition described by the measurement context.  ...  Acknowledgements Thanks to the three anonymous reviewers, Bevan Koopman and Ana Belen Sainz for their constructive input and suggestions.  ... 
doi:10.1016/j.tcs.2017.11.028 fatcat:ofkqryvzs5bgrnghywemdp5o6q

On the implication problem for probabilistic conditional independency

S.K.M. Wong, C.J. Butz, D. Wu
2000 IEEE transactions on systems, man and cybernetics. Part A. Systems and humans  
The implication problem is to test whether a given set of independencies logically implies another independency. This problem is crucial in the design of a probabilistic reasoning system.  ...  Index Terms-Bayesian networks, embedded multivalued dependency, implication problem, probabilistic conditional independence, relational databases.  ...  Moreover, a Markov network is in fact a generalization of an acyclic join dependency.  ... 
doi:10.1109/3468.895901 fatcat:c4mshemp35bfhjgfqc5dueohcq

Querying Relational Databases without Explicit Joins [chapter]

Ramon Lawrence, Ken Barker
2002 Lecture Notes in Computer Science  
Database semantics are described using a global dictionary and semantic specifications that are combined to form an integrated, context view.  ...  Although graphical tools for query construction mask some of the complexity, complex database schema challenge even experienced database users during query formulation because a user is responsible for  ...  and appropriate join conditions.  ... 
doi:10.1007/3-540-46140-x_22 fatcat:twae5vsmnnclbey3z5am5vagxm

A simplied universal relation assumption and its properties

Ronald Fagin, Alberto O. Mendelzon, Jeffrey D. Ullman
1982 ACM Transactions on Database Systems  
We propose a simpler method of describing the real world, where constraints are given by functional dependencies and a single join dependency.  ...  We characterize in terms of hypergrapbs those multivalued dependencies that are the consequence of a given join dependency.  ...  ACKNOWLEDGMENTS The authors are grateful to Catriel Beeri, Maria Klawe, David Maier, and Moshe Vardi for useful suggestions.  ... 
doi:10.1145/319732.319735 fatcat:ixuyssaaq5f7zfw7sqyuopjpie
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