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Topic Review
Focal Point (Game Theory)
In game theory, a focal point (or Schelling point) is a solution that people tend to choose by default in the absence of communication. The concept was introduced by the American economist Thomas Schelling in his book The Strategy of Conflict (1960). Schelling states that "(p)eople can often concert their intentions or expectations with others if each knows that the other is trying to do the same" in a cooperative situation (at page 57), so their action would converge on a focal point which has some kind of prominence compared with the environment. However, the conspicuousness of the focal point depends on time, place and people themselves. It may not be a definite solution.
  • 5.0K
  • 14 Nov 2022
Topic Review
Prince of Wales's Feathers
Template:Infobox Coat of arms The Prince of Wales's feathers is the heraldic badge of the Prince of Wales. It consists of three white ostrich feathers emerging from a gold coronet. A ribbon below the coronet bears the motto Ich dien (German: [ɪç ˈdiːn], "I serve"). As well as being used in royal heraldry, the badge is sometimes used to symbolise Wales, particularly in Welsh rugby union and Welsh regiments of the British Army.
  • 5.0K
  • 27 Nov 2022
Topic Review
Records Continuum Model
The Records Continuum Model (RCM) was created in the 1990s by Monash University academic Frank Upward with input from colleagues Sue McKemmish and Livia Iacovino as a response to evolving discussions about the challenges of managing digital records and archives in the discipline of Archival Science. The RCM was first published in Upward’s 1996 paper "Structuring the Records Continuum – Part One: Postcustodial principles and properties". Upward describes the RCM within the broad context of a continuum where activities and interactions transform documents into records, evidence and memory that are used for multiple purposes over time. Upward places the RCM within a post-custodial, postmodern and structuration conceptual framework. Australian academics and practitioners continue to explore, develop and extend the RCM and records continuum theory, along with international collaborators, via the Records Continuum Research Group (RCRG) at Monash University.
  • 5.0K
  • 09 Nov 2022
Topic Review
Correlation and Dependence
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. In the broadest sense correlation is any statistical association, though it commonly refers to the degree to which a pair of variables are linearly related. Familiar examples of dependent phenomena include the correlation between the height of parents and their offspring, and the correlation between the price of a good and the quantity the consumers are willing to purchase, as it is depicted in the so-called demand curve. Correlations are useful because they can indicate a predictive relationship that can be exploited in practice. For example, an electrical utility may produce less power on a mild day based on the correlation between electricity demand and weather. In this example, there is a causal relationship, because extreme weather causes people to use more electricity for heating or cooling. However, in general, the presence of a correlation is not sufficient to infer the presence of a causal relationship (i.e., correlation does not imply causation). Formally, random variables are dependent if they do not satisfy a mathematical property of probabilistic independence. In informal parlance, correlation is synonymous with dependence. However, when used in a technical sense, correlation refers to any of several specific types of mathematical operations between the tested variables and their respective expected values. Essentially, correlation is the measure of how two or more variables are related to one another. There are several correlation coefficients, often denoted [math]\displaystyle{ \rho }[/math] or [math]\displaystyle{ r }[/math], measuring the degree of correlation. The most common of these is the Pearson correlation coefficient, which is sensitive only to a linear relationship between two variables (which may be present even when one variable is a nonlinear function of the other). Other correlation coefficients – such as Spearman's rank correlation – have been developed to be more robust than Pearson's, that is, more sensitive to nonlinear relationships. Mutual information can also be applied to measure dependence between two variables.
  • 5.0K
  • 14 Oct 2022
Topic Review
Gramian Matrix
In linear algebra, the Gram matrix (or Gramian matrix, Gramian) of a set of vectors [math]\displaystyle{ v_1,\dots, v_n }[/math] in an inner product space is the Hermitian matrix of inner products, whose entries are given by [math]\displaystyle{ G_{ij}=\langle v_i, v_j \rangle }[/math]. An important application is to compute linear independence: a set of vectors are linearly independent if and only if the Gram determinant (the determinant of the Gram matrix) is non-zero. It is named after Jørgen Pedersen Gram.
  • 4.9K
  • 27 Oct 2022
Topic Review
Transmission Dynamics of COVID-19
COVID-19 is pneumonia caused by a novel coronavirus which is an emerging infectious disease, and outbreaks in more than 200 countries around the world. Consequently, the spread principles and prevention and control measures of COVID-19 have become a global problem to be solved. Here, we pose a series of dynamical models to reveal the transmission mechanisms of COVID-19. Based on these mathematical models, data fitting and spread trend of COVID-19 are explored to show the propagation law between human populations. We hope that our work may provide some useful insights for effective control of the COVID-19.
  • 4.9K
  • 28 Oct 2020
Topic Review
Connectivity Architecture
Connectivity architecture connects main functional blocks or entities of a system with well-defined interfaces enabling interoperability, fluent data flows and information sharing in timely manner. Local connectivity architecture defines e.g. the architecture inside an autonomous ship. The wider-scale architecture includes geographically distributed entities such as vessels, databases, and remote operations centers.
  • 4.9K
  • 17 Aug 2020
Topic Review
Limit Point
In mathematics, a limit point (or cluster point or accumulation point) of a set [math]\displaystyle{ S }[/math] in a topological space [math]\displaystyle{ X }[/math] is a point [math]\displaystyle{ x }[/math] that can be "approximated" by points of [math]\displaystyle{ S }[/math] in the sense that every neighbourhood of [math]\displaystyle{ x }[/math] with respect to the topology on [math]\displaystyle{ X }[/math] also contains a point of [math]\displaystyle{ S }[/math] other than [math]\displaystyle{ x }[/math] itself. A limit point of a set [math]\displaystyle{ S }[/math] does not itself have to be an element of [math]\displaystyle{ S. }[/math] There is also a closely related concept for sequences. A cluster point or accumulation point of a sequence [math]\displaystyle{ (x_n)_{n \in \mathbb{N}} }[/math] in a topological space [math]\displaystyle{ X }[/math] is a point [math]\displaystyle{ x }[/math] such that, for every neighbourhood [math]\displaystyle{ V }[/math] of [math]\displaystyle{ x, }[/math] there are infinitely many natural numbers [math]\displaystyle{ n }[/math] such that [math]\displaystyle{ x_n \in V. }[/math] This definition of a cluster or accumulation point of a sequence generalizes to nets and filters. In contrast to sets, for a sequence, net, or filter, the term "limit point" is not synonymous with a "cluster/accumulation point"; by definition, the similarly named notion of a limit point of a filter (respectively, a limit point of a sequence, a limit point of a net) refers to a point that the filter converges to (respectively, the sequence converges to, the net converges to). The limit points of a set should not be confused with adherent points for which every neighbourhood of [math]\displaystyle{ x }[/math] contains a point of [math]\displaystyle{ S }[/math]. Unlike for limit points, this point of [math]\displaystyle{ S }[/math] may be [math]\displaystyle{ x }[/math] itself. A limit point can be characterized as an adherent point that is not an isolated point. Limit points of a set should also not be confused with boundary points. For example, [math]\displaystyle{ 0 }[/math] is a boundary point (but not a limit point) of set [math]\displaystyle{ \{ 0 \} }[/math] in [math]\displaystyle{ \R }[/math] with standard topology. However, [math]\displaystyle{ 0.5 }[/math] is a limit point (though not a boundary point) of interval [math]\displaystyle{ [0, 1] }[/math] in [math]\displaystyle{ \R }[/math] with standard topology (for a less trivial example of a limit point, see the first caption). This concept profitably generalizes the notion of a limit and is the underpinning of concepts such as closed set and topological closure. Indeed, a set is closed if and only if it contains all of its limit points, and the topological closure operation can be thought of as an operation that enriches a set by uniting it with its limit points.
  • 4.8K
  • 25 Oct 2022
Topic Review
Synthetic Aperture Radar
SAR constellations 
  • 4.8K
  • 24 Aug 2020
Topic Review
The Sims 3 Stuff Packs
Stuff packs are minor expansion packs for The Sims 3 that add new items, clothing, and furniture to the game without implementing any significant changes to gameplay.
  • 4.8K
  • 11 Nov 2022
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