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πŸ”— Proofs from the Book

πŸ”— Mathematics πŸ”— Books

Proofs from THE BOOK is a book of mathematical proofs by Martin Aigner and GΓΌnter M. Ziegler. The book is dedicated to the mathematician Paul ErdΕ‘s, who often referred to "The Book" in which God keeps the most elegant proof of each mathematical theorem. During a lecture in 1985, ErdΕ‘s said, "You don't have to believe in God, but you should believe in The Book."

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πŸ”— Main Core – database of US citizens believed to be threats to national security

πŸ”— United States/U.S. Government πŸ”— United States πŸ”— Human rights πŸ”— Mass surveillance πŸ”— Espionage πŸ”— United States/FBI

Main Core is the code name of an American governmental database that is believed to have been in existence since the 1980s. It is believed that Main Core is a federal database containing personal and financial data of millions of United States citizens believed to be threats to national security.

πŸ”— Theory of Constraints

πŸ”— Technology πŸ”— Business πŸ”— Marketing & Advertising

The theory of constraints (TOC) is a management paradigm that views any manageable system as being limited in achieving more of its goals by a very small number of constraints. There is always at least one constraint, and TOC uses a focusing process to identify the constraint and restructure the rest of the organization around it. TOC adopts the common idiom "a chain is no stronger than its weakest link". That means that organizations and processes are vulnerable because the weakest person or part can always damage or break them, or at least adversely affect the outcome.

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πŸ”— Stanford Bunny

πŸ”— Computing πŸ”— Computer graphics

The Stanford bunny is a computer graphics 3D test model developed by Greg Turk and Marc Levoy in 1994 at Stanford University. The model consists of 69,451 triangles, with the data determined by 3D scanning a ceramic figurine of a rabbit. This figurine and others were scanned to test methods of range scanning physical objects.

The data can be used to test various graphics algorithms, including polygonal simplification, compression, and surface smoothing. There are a few complications with this dataset that can occur in any 3D scan data: the model is manifold connected and has holes in the data, some due to scanning limits and some due to the object being hollow. These complications provide a more realistic input for any algorithm that is benchmarked with the Stanford bunny, though by today's standards, in terms of geometric complexity and triangle count, it is considered a simple model.

The model was originally available in .ply (polygons) file format with 4 different resolutions.

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πŸ”— Republic of Molossia – A Micronation in the US

πŸ”— United States πŸ”— Nevada πŸ”— Micronations

The Republic of Molossia, also known as Molossia, is a micronation claiming sovereignty over 1.28 acres of land near Dayton, Nevada. The micronation has not received recognition from any of the member states of the United Nations. It was founded by Kevin Baugh. On April 16, 2016, Baugh hosted a tour of Molossia, sponsored by the website Atlas Obscura. He continues to pay property taxes on the land to Storey County (the recognized local government), although he calls it "foreign aid". He has stated "We all want to think we have our own country, but you know the U.S. is a lot bigger".

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πŸ”— Fractional calculus

πŸ”— Mathematics

Fractional calculus is a branch of mathematical analysis that studies the several different possibilities of defining real number powers or complex number powers of the differentiation operator D

D f ( x ) = d d x f ( x ) , {\displaystyle Df(x)={\frac {d}{dx}}f(x)\,,}

and of the integration operator J

J f ( x ) = ∫ 0 x f ( s ) d s , {\displaystyle Jf(x)=\int _{0}^{x}f(s)\,ds\,,}

and developing a calculus for such operators generalizing the classical one.

In this context, the term powers refers to iterative application of a linear operator D to a function f, that is, repeatedly composing D with itself, as in D 2 ( f ) = ( D ∘ D ) ( f ) = D ( D ( f ) ) {\displaystyle D^{2}(f)=(D\circ D)(f)=D(D(f))} .

For example, one may ask for a meaningful interpretation of:

D = D 1 2 {\displaystyle {\sqrt {D}}=D^{\frac {1}{2}}}

as an analogue of the functional square root for the differentiation operator, that is, an expression for some linear operator that when applied twice to any function will have the same effect as differentiation. More generally, one can look at the question of defining a linear functional

D a {\displaystyle D^{a}}

for every real-number a in such a way that, when a takes an integer value n ∈ β„€, it coincides with the usual n-fold differentiation D if n > 0, and with the βˆ’nth power of J when n < 0.

One of the motivations behind the introduction and study of these sorts of extensions of the differentiation operator D is that the sets of operator powers { Da |a ∈ ℝ } defined in this way are continuous semigroups with parameter a, of which the original discrete semigroup of { Dn | n ∈ β„€ } for integer n is a denumerable subgroup: since continuous semigroups have a well developed mathematical theory, they can be applied to other branches of mathematics.

Fractional differential equations, also known as extraordinary differential equations, are a generalization of differential equations through the application of fractional calculus.

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πŸ”— Brabant Killers

πŸ”— Crime πŸ”— Organized crime πŸ”— Belgium

The Brabant killers, also named the Nijvel Gang in Dutch-speaking media (Dutch: De Bende van Nijvel), and the mad killers of Brabant in French-speaking media (French: Les Tueurs fous du Brabant), are believed to be responsible for a series of violent attacks that mainly occurred in the Belgian province of Brabant between 1982 and 1985. A total of 28 people died and 22 were injured. The actions of the gang, believed to consist of a core of three men, made it Belgium's most notorious unsolved crime spree. The active participants were known as The Giant (a tall man who may have been the leader); the Killer (the main shooter) and the Old Man (a middle aged man who drove). The identities and whereabouts of the "Brabant killers" are unknown. Although significant resources are still dedicated to it, the most recent arrests in the case were of the now-retired original senior detectives. Failure to catch the gang resulted in a parliamentary inquiry. There have been many theories of ulterior motives behind the crimes.

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πŸ”— Musth

πŸ”— Mammals

Musth or must (an Urdu word, from Persian, lit. drunk) is a periodic condition in bull (male) elephants characterized by highly aggressive behavior and accompanied by a large rise in reproductive hormones.

Testosterone levels in an elephant in musth can be on average 60 times greater than in the same elephant at other times (in specific individuals these testosterone levels can even reach as much as 140 times the normal). However, whether this hormonal surge is the sole cause of musth, or merely a contributing factor, is unknown.

Scientific investigation of musth is problematic because even the most placid elephants become highly violent toward humans and other elephants during musth.

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  • "Musth" | 2020-04-06 | 77 Upvotes 15 Comments

πŸ”— The High Cost of Free Parking

πŸ”— Books πŸ”— Urban studies and planning

The High Cost of Free Parking is an urban planning book by UCLA professor Donald Shoup dealing with the costs of free parking on society. It is structured as a criticism of the planning and regulation of parking and recommends that parking be built and allocated according to its fair market value. It incorporates elements of Shoup's Georgist philosophy.

The book was originally published in 2005 by the American Planning Association and the Planners Press. A revised edition was released in 2011 by Routledge.

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πŸ”— Ken Leishman

πŸ”— Biography πŸ”— Aviation πŸ”— Aviation/Aviation accident πŸ”— Canada πŸ”— Finance & Investment πŸ”— Aviation/aerospace biography πŸ”— Crime and Criminal Biography πŸ”— Crime and Criminal Biography/Organized crime

Kenneth Leishman (June 20, 1931 – December 14, 1979), also known as the Flying Bandit or the Gentleman Bandit was a Canadian criminal responsible for multiple robberies between 1957 and 1966. Leishman was the mastermind behind the largest gold theft in Canadian history. This record stood for over 50 years, until it was surpassed by the Toronto Pearson airport heist in 2023. After being caught and arrested by the Royal Canadian Mounted Police (RCMP), Leishman managed to escape twice, before being caught and serving the remainder of his various sentences.

In December 1979, while flying a Mercy Flight to Thunder Bay, Leishman's aircraft crashed about 40 miles (64Β km) north of Thunder Bay.