Extending the Relational Algebra for Relations with Maybe Tuples and Existential and Universal Null Values

1984 ◽  
Vol 7 (1) ◽  
pp. 129-150
Author(s):  
Joachim Biskup
Keyword(s):  
Relational Algebra ◽  
Null Value ◽  
Null Values ◽  
A Minor

We study operations on generalized database relations which possibly contain maybe tuples and two types of null values. The existential null value has the meaning “value at present unknown” whereas the universal null value has the meaning “value arbitrary”. For extending a usual relational operation to generalized relations we develop three requirements: adequacy, restrictedness, and feasibility. As demonstrated for the natural join as an example, we can essetially meet these requirements although we are faced with a minor tradeoff between restrictedness and feasibility.

scholarly journals Rejecting or Accepting Parameter Values in Bayesian Estimation

2018 ◽  
Vol 1 (2) ◽  
pp. 270-280 ◽  
Author(s):  
John K. Kruschke
Keyword(s):  
Decision Rule ◽  
Bayes Factors ◽  
Posterior Distributions ◽  
P Values ◽  
Plausible Values ◽  
Null Value ◽  
Null Values ◽  
Highest Density Interval ◽  
Region Of Practical Equivalence ◽  
Parameter Values

This article explains a decision rule that uses Bayesian posterior distributions as the basis for accepting or rejecting null values of parameters. This decision rule focuses on the range of plausible values indicated by the highest density interval of the posterior distribution and the relation between this range and a region of practical equivalence (ROPE) around the null value. The article also discusses considerations for setting the limits of a ROPE and emphasizes that analogous considerations apply to setting the decision thresholds for p values and Bayes factors.

scholarly journals Resolving Interoperability Issues of Precision and Array with Null Value of Web Services Using WSIG-JADE Framework

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jaspreet Chawla ◽  
Anil Kr Ahlawat ◽  
Jyoti Gautam
Keyword(s):  
Web Services ◽  
Multiagent System ◽  
Data Sets ◽  
String Length ◽  
A Value ◽  
Empty String ◽  
Whole Number ◽  
Null Value ◽  
Null Values ◽  
Data Elements

Web services and agent technology play a significant role while resolving the issues related to platform interoperability. Web service interoperability organization (WS-I) provided the guidelines to remove the interoperability issues using basic profile 1.1/1.2 product. However, issues are still arising while transferring the precision values and an array with null values between different platforms like JAVA and .NET. As in a precision issue, JAVA supports data precision up to the 6th value and .NET up to the 5th value after the decimal and after increasing their limits, the whole number gets rounded off. In array with a null value issue, JAVA treats null as a value but .NET treats null as an empty string. To remove these issues, we use the WSIG-JADE framework that helps to build and demonstrate a multiagent system that does the mapping and conversions between agents and web services. It limits the number of digits to the 5th place after the decimal thereby increasing the precision in data sets, whereas it treats null as an empty string so that string length remains the same for both the platforms thereby helping in the correct count of data elements.

Optimizing the Accuracy of Entity-Based Data Integration of Multiple Data Sources Using Genetic Programming Methods

2012 ◽  
Vol 3 (1) ◽  
pp. 72-82 ◽  
Author(s):  
Yinle Zhou ◽  
Ali Kooshesh ◽  
John Talburt
Keyword(s):  
Genetic Programming ◽  
Data Integration ◽  
Synthetic Data ◽  
Multiple Data ◽  
Null Value ◽  
Selection Operators ◽  
Series Of Experiments ◽  
Null Values ◽  
Selection Operator ◽  
Different Sources

Entity-based data integration (EBDI) is a form of data integration in which information related to the same real-world entity is collected and merged from different sources. It often happens that not all of the sources will agree on one value for a common attribute. These cases are typically resolved by invoking a rule that will select one of the non-null values presented by the sources. One of the most commonly used selection rules is called the naïve selection operator that chooses the non-null value provided by the source with the highest overall accuracy for the attribute in question. However, the naïve selection operator will not always produce the most accurate result. This paper describes a method for automatically generating a selection operator using methods from genetic programming. It also presents the results from a series of experiments using synthetic data that indicate that this method will yield a more accurate selection operator than either the naïve or naïve-voting selection operators.

A Fully Precise Null Extended Nested Relational Algebra

1993 ◽  
Vol 19 (3-4) ◽  
pp. 303-342
Author(s):  
Mark Levene ◽  
George Loizou
Keyword(s):  
Normal Form ◽  
General Class ◽  
Relational Algebra ◽  
Relational Model ◽  
Detailed Structure ◽  
Complex Objects ◽  
Nested Relations ◽  
Null Values

The nested relational model extends the fiat relational model by relaxing the first normal form assumption in order to allow the modelling of complex objects. Recently many extended algebras have been suggested for the nested relational model, but only few have incorporated null values into the attribute domains. Furthermore, some of the previously defined extended algebras are defined only over a subclass of nested relations, and all of them are difficult to use, since the user must know the detailed structure of the nested relations being queried. Herein, we define an extended algebra for nested relations, which may contain null values, called the null extended algebra. The null extended algebra is defined over the general class of nested relations with null values and, in addition, allows queries to be formulated without the user having to know the detailed structure of the nested relations being queried. In this sense, our null extended join operator of the null extended algebra is unique in the literature, since it joins two nested relations by taking into account all their common attributes at all levels of their structure, whilst operating directly on the two nested relations. All the operators of the null extended algebra are proved to be faithful and precise. The null extended algebra is a complete extended algebra in the context of nested relations, and, in addition, it includes the null extended powerset operator, which provides recursion and iteration facilities.

scholarly journals Rejecting or accepting parameter values in Bayesian estimation

2018 ◽  
Author(s):  
John K. Kruschke
Keyword(s):  
Decision Rule ◽  
Bayes Factors ◽  
Posterior Distributions ◽  
P Values ◽  
Plausible Values ◽  
Null Value ◽  
Null Values ◽  
Highest Density Interval ◽  
Region Of Practical Equivalence ◽  
Parameter Values

This article explains a decision rule for accepting or rejecting null values of parameters, based on Bayesian posterior distributions. The decision rule considers a range of plausible values indicated by the highest density interval (HDI) of the posterior distribution, and its relation to a region of practical equivalence (ROPE) around the null value. The article discusses considerations for setting the limits of a ROPE and emphasizes that analogous considerations apply to setting the decision thresholds for p values and Bayes factors.

Rating Post-Operative Backs (Part I)

1997 ◽  
Vol 2 (4) ◽  
pp. 1-3
Author(s):  
James B. Talmage
Keyword(s):  
Spinal Stenosis ◽  
Foot Drop ◽  
Neurogenic Claudication ◽  
Root Damage ◽  
Fourth Edition ◽  
Minor Strain ◽  
Injury Model ◽  
Strain Type ◽  
A Minor ◽  
Anterior Tibialis

Abstract The AMA Guides to the Evaluation of Permanent Impairment, Fourth Edition, uses the Injury Model to rate impairment in people who have experienced back injuries. Injured individuals who have not required surgery can be rated using differentiators. Challenges arise when assessing patients whose injuries have been treated surgically before the patient is rated for impairment. This article discusses five of the most common situations: 1) What is the impairment rating for an individual who has had an injury resulting in sciatica and who has been treated surgically, either with chemonucleolysis or with discectomy? 2) What is the impairment rating for an individual who has a back strain and is operated on without reasonable indications? 3) What is the impairment rating of an individual with sciatica and a foot drop (major anterior tibialis weakness) from L5 root damage? 4) What is the rating for an individual who is injured, has true radiculopathy, undergoes a discectomy, and is rated as Category III but later has another injury and, ultimately, a second disc operation? 5) What is the impairment rating for an older individual who was asymptomatic until a minor strain-type injury but subsequently has neurogenic claudication with severe surgical spinal stenosis on MRI/myelography? [Continued in the September/October 1997 The Guides Newsletter]

Pelvic Impairments

2018 ◽  
Vol 23 (4) ◽  
pp. 9-10
Author(s):  
James Talmage ◽  
Jay Blaisdell
Keyword(s):  
Pelvic Ring ◽  
Reproductive Organs ◽  
High Impact ◽  
Pelvic Fractures ◽  
Motor Dysfunction ◽  
Impact Event ◽  
Concomitant Injuries ◽  
Rating Process ◽  
Pass Through ◽  
A Minor

Abstract Pelvic fractures are relatively uncommon, and in workers’ compensation most pelvic fractures are the result of an acute, high-impact event such as a fall from a roof or an automobile collision. A person with osteoporosis may sustain a pelvic fracture from a lower-impact injury such as a minor fall. Further, major parts of the bladder, bowel, reproductive organs, nerves, and blood vessels pass through the pelvic ring, and traumatic pelvic fractures that result from a high-impact event often coincide with damaged organs, significant bleeding, and sensory and motor dysfunction. Following are the steps in the rating process: 1) assign the diagnosis and impairment class for the pelvis; 2) assign the functional history, physical examination, and clinical studies grade modifiers; and 3) apply the net adjustment formula. Because pelvic fractures are so uncommon, raters may be less familiar with the rating process for these types of injuries. The diagnosis-based methodology for rating pelvic fractures is consistent with the process used to rate other musculoskeletal impairments. Evaluators must base the rating on reliable data when the patient is at maximum medical impairment and must assess possible impairment from concomitant injuries.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Sign in / Sign up

Export Citation Format

Share Document