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πŸ”— Swiss Railway Clock

πŸ”— Time πŸ”— Switzerland πŸ”— Trains πŸ”— Trains/Stations

The Swiss railway clock was designed in 1944 by Hans Hilfiker, a Swiss engineer and Swiss Federal Railways (SBB) employee, together with Moser-Baer, a Swiss clock manufacturer, for use by the SBB as a station clock. In 1953, Hilfiker added a red second hand in the shape of the baton used by train dispatch staff., giving the clock its current appearance.

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πŸ”— Gridcoin: An open source cryptocurrency that rewards work performed on the BOINC

πŸ”— Computing πŸ”— Computing/Software πŸ”— Numismatics πŸ”— Numismatics/Cryptocurrency πŸ”— Cryptocurrency

Gridcoin (ticker: GRC) is an open source cryptocurrency which securely rewards volunteer computing performed on the BOINC, a distributed computing platform that is home to over 30 science projects spanning a range of scientific disciplines.

Gridcoin attempts to address and ease the environmental energy impact of cryptocurrency mining through its proof-of-research and proof-of-stake protocols, as compared to the proof of work system used by Bitcoin.

πŸ”— Hitler and Mannerheim Recording

πŸ”— Germany πŸ”— Military history πŸ”— Military history/World War II πŸ”— Military history/German military history πŸ”— European history πŸ”— Military history/Nordic military history πŸ”— Finland πŸ”— Military history/European military history

The Hitler and Mannerheim recording is a recording of a private conversation between Adolf Hitler, FΓΌhrer of Nazi Germany, and Field Marshal Carl Gustaf Emil Mannerheim, Commander-in-Chief of the Finnish Defence Forces. It took place on a secret visit made to Finland by Hitler to honour Mannerheim's 75th birthday on 4 June 1942, during the Continuation War, a sub-theatre of World War II. Thor Damen, a sound engineer for the Finnish broadcaster Yleisradio (YLE) who had been assigned to record the official birthday proceedings, recorded the first eleven minutes of Hitler and Mannerheim's private conversationβ€”without Hitler's knowledge. It is the only known recording of Hitler speaking in an unofficial tone.

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πŸ”— Garfield's proof of the Pythagorean Theorem

πŸ”— United States πŸ”— Mathematics

Garfield's proof of the Pythagorean theorem is an original proof of the Pythagorean theorem discovered by James A. Garfield (November 19, 1831 – September 19, 1881), the 20th president of the United States. The proof appeared in print in the New-England Journal of Education (Vol. 3, No.14, April 1, 1876). At the time of the publication of the proof Garfield was a congressman from Ohio. He assumed the office of President on March 4, 1881, and served in that position until his death on September 19, 1881, having succumbed to injuries sustained when he was shot in an assassination in July. Garfield is thus far the only President of the United States to have contributed anything original to mathematics. The proof is nontrivial and, according to the historian of mathematics William Dunham, "Garfield's is really a very clever proof." The proof appears as the 231st proof in The Pythagorean Proposition, a compendium of 370 different proofs of the Pythagorean theorem.

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πŸ”— They Live

πŸ”— Film πŸ”— Film/American cinema πŸ”— Science Fiction

They Live is a 1988 American science fiction action horror film written and directed by John Carpenter, based on the 1963 short story "Eight O'Clock in the Morning" by Ray Nelson. Starring Roddy Piper, Keith David, and Meg Foster, the film follows an unnamed drifter who discovers through special sunglasses that the ruling class are aliens concealing their appearance and manipulating people to consume, breed, and conform to the status quo via subliminal messages in mass media.

Having acquired the film rights to the Nelson-penned short story prior to the production of They Live, Carpenter used the story as the basis for the screenplay's structure, which he wrote under the pseudonym "Frank Armitage". Carpenter has stated that the themes of They Live stemmed from his dissatisfaction with the economic policies of then-U.S. President Ronald Reagan, as well as what Carpenter saw as increasing commercialization in both popular culture and politics.

They Live was a minor success upon release, debuting at #1 at the North American box office. It initially received negative reviews from critics, who lambasted its social commentary, writing, and acting; however, it later gained a cult following and experienced a significantly more favorable critical reception. It is now regarded by many as one of Carpenter's best films. The film has also entered the pop culture lexicon, notably having a lasting effect on street art (particularly that of Shepard Fairey).

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πŸ”— VRML – Virtual Reality Markup Language

πŸ”— Computing πŸ”— Computing/Software πŸ”— Computing/Websites

VRML (Virtual Reality Modeling Language, pronounced vermal or by its initials, originallyβ€”before 1995β€”known as the Virtual Reality Markup Language) is a standard file format for representing 3-dimensional (3D) interactive vector graphics, designed particularly with the World Wide Web in mind. It has been superseded by X3D.

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πŸ”— Pattern theory

πŸ”— Mathematics

Pattern theory, formulated by Ulf Grenander, is a mathematical formalism to describe knowledge of the world as patterns. It differs from other approaches to artificial intelligence in that it does not begin by prescribing algorithms and machinery to recognize and classify patterns; rather, it prescribes a vocabulary to articulate and recast the pattern concepts in precise language. Broad in its mathematical coverage, Pattern Theory spans algebra and statistics, as well as local topological and global entropic properties.

In addition to the new algebraic vocabulary, its statistical approach is novel in its aim to:

  • Identify the hidden variables of a data set using real world data rather than artificial stimuli, which was previously commonplace.
  • Formulate prior distributions for hidden variables and models for the observed variables that form the vertices of a Gibbs-like graph.
  • Study the randomness and variability of these graphs.
  • Create the basic classes of stochastic models applied by listing the deformations of the patterns.
  • Synthesize (sample) from the models, not just analyze signals with them.

The Brown University Pattern Theory Group was formed in 1972 by Ulf Grenander. Many mathematicians are currently working in this group, noteworthy among them being the Fields Medalist David Mumford. Mumford regards Grenander as his "guru" in Pattern Theory.

πŸ”— A*

πŸ”— Computing πŸ”— Computer science πŸ”— Mathematics

A* (pronounced "A-star") is a graph traversal and path search algorithm, which is often used in computer science due to its completeness, optimality, and optimal efficiency. One major practical drawback is its O ( b d ) {\displaystyle O(b^{d})} space complexity, as it stores all generated nodes in memory. Thus, in practical travel-routing systems, it is generally outperformed by algorithms which can pre-process the graph to attain better performance, as well as memory-bounded approaches; however, A* is still the best solution in many cases.

Peter Hart, Nils Nilsson and Bertram Raphael of Stanford Research Institute (now SRI International) first published the algorithm in 1968. It can be seen as an extension of Edsger Dijkstra's 1959 algorithm. A* achieves better performance by using heuristics to guide its search.

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  • "A*" | 2019-08-10 | 50 Upvotes 6 Comments