Like other analysis techniques, the ERD uses simple boxes, lines, and symbols to diagram the entities, attributes, and data relationships. The entities are the uniquely identifiable people, things, or concepts whose information is important to the business; the attributes are distinguishing characteristics of the entity; and the relationships explain how the entities share data.
In Venn diagrams, the curves are overlapped in every possible way, showing all possible relations between the sets. They are thus a special case of Euler diagrams, which do not necessarily show all relations. Venn diagrams were conceived around 1880 by John Venn. They are used to teach elementary set theory, as well as illustrate simple set relationships in probability, logic, statistics, linguistics, and computer science.
a curved line used to represent an exclusive relationship in an entity-relationship diagram
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Venn himself did not use the term "Venn diagram" and referred to his invention as "Eulerian Circles".[7] For example, in the opening sentence of his 1880 article Venn writes, "Schemes of diagrammatic representation have been so familiarly introduced into logical treatises during the last century or so, that many readers, even those who have made no professional study of logic, may be supposed to be acquainted with the general nature and object of such devices. Of these schemes one only, viz. that commonly called 'Eulerian circles,' has met with any general acceptance..."[5][6] Lewis Carroll (Charles L. Dodgson) includes "Venn's Method of Diagrams" as well as "Euler's Method of Diagrams" in an "Appendix, Addressed to Teachers" of his book Symbolic Logic (4th edition published in 1896). The term "Venn diagram" was later used by Clarence Irving Lewis in 1918, in his book A Survey of Symbolic Logic.[8][9]
Use to show the relationship to a central idea in a cycle. The first line of Level 1 text corresponds to the central shape, and its Level 2 text corresponds to the surrounding circular shapes. Unused text does not appear, but remains available if you switch layouts.
Use to show the relationship to a central idea in a cyclical progression. Each of the first four lines of Level 1 text corresponds to a wedge or pie shape, and Level 2 text appears in a rectangular shape to the side of the wedge or pie shape. Unused text does not appear, but remains available if you switch layouts.
Use to show relationships to a central idea in a cycle. The first Level 1 line of text corresponds to the central circular shape. Emphasizes the surrounding circles rather than the central idea. Unused text does not appear, but remains available if you switch layouts.
Use to show the relationship to a central idea. Emphasizes both information in the center circle and how information in the outer ring of circles contributes to the central idea. The first Level 1 line of text corresponds to the central circle, and its Level 2 text corresponds to the outer ring of circles. Unused text does not appear, but remains available if you switch layouts.
Use to show both overlapping relationships and the relationship to a central idea in a cycle. The first line of Level 1 text corresponds to the central shape and the lines of Level 2 text correspond to the surrounding circular shapes. Unused text does not appear, but remains available if you switch layouts.
Use to compare or show the relationship between two ideas. Each of the first two lines of Level 1 text corresponds to text at the top of one side of the center point. Emphasizes Level 2 text, which is limited to four shapes on each side of the center point. The balance tips towards the side with the most shapes containing Level 2 text. Unused text does not appear, but remains available if you switch layouts.
Use to show containment, gradations, or hierarchical relationships. The first five lines of Level 1 text are associated with a circle. Unused text does not appear, but remains available if you switch layouts.
Use to show overlapping or interconnected relationships. The first seven lines of Level 1 text correspond with a circle. If there are four or fewer lines of Level 1 text, the text is inside the circles. If there are more than four lines of Level 1 text, the text is outside of the circles. Unused text does not appear, but remains available if you switch layouts.
Use to show relationships of concepts or components to a central idea in a cycle. The first line of Level 1 text corresponds to the central circular shape and the lines of Level 2 text correspond to the surrounding rectangular shapes. Unused text does not appear, but remains available if you switch layouts.
Use to show containment relationships. Each of the first three lines of Level 1 text correspond to the upper left text in the shapes, and Level 2 text corresponds to the smaller shapes. Works best with minimal Level 2 lines of text. Unused text does not appear, but remains available if you switch layouts.
Use to show containment, proportional, or interconnected relationships. The first nine lines of Level 1 text appear in the triangular shapes. Unused text does not appear, but remains available if you switch layouts. Works best with Level 1 text only.
Use to show overlapping relationships. A good choice for emphasizing growth or gradation. Works best with Level 1 text only. The first seven lines of Level 1 text correspond to a circular shape. Unused text does not appear, but remains available if you switch layouts.
Use to show the relationship of components to a whole in quadrants. The first four lines of Level 1 text appear in the quadrants. Unused text does not appear, but remains available if you switch layouts.
Use to show the relationships of four quadrants to a whole. The first line of Level 1 text corresponds to the central shape, and the first four lines of Level 2 text appear in the quadrants. Unused text does not appear, but remains available if you switch layouts.
It represents at most 1 participating in the relation, so if both entities having an arrow from the relationship it will be 1 to 1 relationship and when there is a single line in both sides it will be M to M relationship.
All these examples come from different domains. Despite that, they follow the same abstract idea.That idea can be represented graphically on an entity-relationship diagram.It does not matter whether we store this information in a relational database, in an XML fileor in memory objects.
One-to-one relationships can be represented as a plain line.In a such relationship, two objects form a pair.If we have a one-to-one relationship A-B, then we have the following rules:
Graphs are most frequently used for displaying time associations and patterns in epidemiologic data. These graphs can include line graphs, histograms (epidemic curves), and scatter diagrams (see Box 6.4 for general guidelines in construction of epidemiologic graphs).
Contact diagrams are versatile tools for revealing relationships between individual cases in time. In contact diagrams (Figure 6.2, panel A) (5), which are commonly used for visualizing person-to-person transmission, different markers are used to indicate the different groups exposed or at risk.Epidemic Curves
The scatter diagram graphs pairs of numerical data, with one variable on each axis, to look for a relationship between them. If the variables are correlated, the points will fall along a line or curve. The better the correlation, the tighter the points will hug the line. This cause analysis tool is considered one of the seven basic quality tools.
In the left part of the diagram, in the middle, there is a box, with black outline and light gray background. This box is labeled "VERIFIABLE DATA REGISTRY" and contains a symbol representing a graph with nodes and arcs. From this box, one arrow, labeled "resolve()", extends upwards and points to the top half of the diagram where the grey-outlined rectangle is located. Another arrow, labeled "resolveRepresentation()", extends downwards and points to the bottom half of the diagram, where the row of three black-outlined rectangles is located. 2ff7e9595c
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