Random Articles (Page 6)
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๐ Canadian Traveller Problem
In computer science and graph theory, the Canadian traveller problem (CTP) is a generalization of the shortest path problem to graphs that are partially observable. In other words, the graph is revealed while it is being explored, and explorative edges are charged even if they do not contribute to the final path.
This optimization problem was introduced by Christos Papadimitriou and Mihalis Yannakakis in 1989 and a number of variants of the problem have been studied since. The name supposedly originates from conversations of the authors who learned of a difficulty Canadian drivers had: traveling a network of cities with snowfall randomly blocking roads. The stochastic version, where each edge is associated with a probability of independently being in the graph, has been given considerable attention in operations research under the name "the Stochastic Shortest Path Problem with Recourse" (SSPPR).
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- "Canadian Traveller Problem" | 2019-05-27 | 20 Upvotes 1 Comments
๐ The Clacks - discworld semaphore
The technology depicted in Terry Pratchett's Discworld novels takes two forms: magical and mechanical. Nearly all technology early in the series is at least partially magical, but in more recent books, a form of industrial revolution takes place, with numerous purely mechanical inventions being introduced. In Thud! ancient 'devices' of undisclosed origin and great power were introduced; it is not clear whether these are magical, mechanical, both or neither. Time-travel technology, the exact nature of which is usually unclear, is used by the History Monks. Most Discworld technologies have real-world equivalents, in function if not form.
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- "The Clacks - discworld semaphore" | 2009-12-09 | 20 Upvotes 3 Comments
๐ Sharp X68000
The X68000 (Japanese: ใจใใฏใน ใใใพใใฏใฃใใ, Hepburn: Ekkusu Rokuman Hassen) is a home computer created by Sharp Corporation, first released in 1987, sold only in Japan.
The first model features a 10 MHz Motorola 68000 CPU (hence the name), 1 MB of RAM, and no hard drive; the last model was released in 1993 with a 25ย MHz Motorola 68030 CPU, 4 MB of RAM, and optional 80ย MB SCSI hard drive. RAM in these systems is expandable to 12 MB, though most games and applications do not require more than 2 MB.
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- "Sharp X68000" | 2025-05-24 | 25 Upvotes 9 Comments
- "Sharp X68000" | 2019-04-21 | 64 Upvotes 25 Comments
๐ Howland Will Forgery Trial
The Howland will forgery trial was a U.S. court case in 1868 to decide Henrietta Howland Robinson's contest of the will of Sylvia Ann Howland. It is famous for the forensic use of mathematics by Benjamin Peirce as an expert witness.
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- "Howland Will Forgery Trial" | 2020-07-31 | 66 Upvotes 21 Comments
๐ Better Portable Graphics
Better Portable Graphics (BPG) is a file format for coding digital images, which was created by programmer Fabrice Bellard in 2014. He has proposed it as a replacement for the JPEG image format as the more compression-efficient alternative in terms of image quality or file size.
It is based on the intra-frame encoding of the High Efficiency Video Coding (HEVC) video compression standard. Tests on photographic images in July 2014 found that BPG produced smaller files for a given quality than JPEG, JPEG XR and WebP.
The format has been designed to be portable and work in low memory environments, and used in portable handheld and IoT devices, where those properties are particularly important. Current research works on designing and developing more energy-efficient BPG hardware which can then be integrated in portable devices such as digital cameras.
While there is no built-in native support for BPG in any mainstream browsers, websites can still deliver BPG images to all browsers by including a JavaScript library written by Bellard.
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- "Better Portable Graphics" | 2019-07-12 | 186 Upvotes 123 Comments
๐ The court case that allowed us to connect to the phone network
Hush-A-Phone v. United States, 238 F.2d 266 (D.C. Cir. 1956) was a seminal ruling in United States telecommunications decided by the D.C. Circuit Court of Appeals. Hush-A-Phone Corporation marketed a small, cup-like device which mounted on the speaking party's microphone, reducing the risk of conversations being overheard and increasing sound fidelity for the listening party. At the time, AT&T had a near-monopoly on America's phone system, even controlling the equipment attached to its network. In this era, Americans had to lease equipment from "Ma Bell" or use approved devices. At this time Hush-A-Phone had been around for 20 years without any issues. However, when an AT&T lawyer saw one in a store window, the company decided to sue on the grounds that anything attached to a phone could damage their network.
AT&T, citing the Communications Act of 1934, which stated in part that the company had the right to make changes and dictate "the classifications, practices, and regulations affecting such charges," claimed the right to "forbid attachment to the telephone of any device 'not furnished by the telephone company.'"
Initially, the Federal Communications Commission (FCC) ruled in AT&T's favor. It found that the device was a "foreign attachment" subject to AT&T control and that unrestricted use of the device could, in the commission's opinion, result in a general deterioration of the quality of telephone service.
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- "The court case that allowed us to connect to the phone network" | 2024-02-22 | 15 Upvotes 2 Comments
๐ Holographic Data Storage
Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium, holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage.
๐ Kleroterion
A kleroterion (Ancient Greek: ฮบฮปฮทฯฯฯฮฎฯฮนฮฟฮฝ) was a randomization device used by the Athenian polis during the period of democracy to select citizens to the boule, to most state offices, to the nomothetai, and to court juries.
The kleroterion was a slab of stone incised with rows of slots and with an attached tube. Citizens' tokensโpinakiaโwere placed randomly in the slots so that every member of each of the tribes of Athens had their tokens placed in the same column. There was a pipe attached to the stone which could then be fed dice that were coloured differently (assumed to be black and white) and could be released individually by a mechanism that has not survived to posterity (but is speculated to be by two nails; one used to block the open end and another to separate the next die to fall from the rest of the dice above it). When a die was released, a complete row of tokens (so, one citizen from each of the tribes of Athens) was either selected if the die was coloured one colour, or discarded if it was the alternate colour. This process continued until the requisite number of citizens was selected.
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- "Kleroterion" | 2019-09-04 | 99 Upvotes 22 Comments
๐ F-Law
Management f-Laws are subversive epigrams about common management practices. Based on observation and experience, they are used to draw attention to entrenched ways of thinking about management and business that are often at odds with common sense or our actual experience.
Systems theorist Russell L. Ackoff, his co-author Herbert J. Addison and Sally Bibb invented the term in 2006 to describe their series of over 100 distilled observations of bad leadership and the misplaced wisdom that often surrounds management in organizations. Ackoff and Addison's f-Laws might seem counter-intuitive. They are designed to challenge organizations' unquestioning adherence to established management habits or beliefs. Many of the f-Laws describe a relationship of inverse proportionality, in example: "The lower the rank of managers, the more they know about fewer things."
The f-Laws advocate adopting a positive, forward-looking and interactive approach to structural or systematic change within organizations, following the principles of idealized design. This is a process that "involves redesigning the organization on the assumption that it was destroyed last night... The most effective way of creating the future is by closing or reducing the gap between the current state and the idealized design".
Three collections of f-Laws entitled A Little Book of f-Laws: 13 Common Sins of Management, Management f-Laws: How Organizations Really Work and Systems Thinking for Curious Managers have been published. While, if read in isolation, each f-Law is a witty and thought-provoking axiom, the books provide a context that draws upon systems thinking and the debate over the importance of developing soft skills in business environments.
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- "F-Law" | 2020-11-07 | 19 Upvotes 2 Comments
๐ Mass Noun
In linguistics, a mass noun, uncountable noun, non-count noun, uncount noun, or just uncountable, is a noun with the syntactic property that any quantity of it is treated as an undifferentiated unit, rather than as something with discrete elements. Non-count nouns are distinguished from count nouns.
Given that different languages have different grammatical features, the actual test for which nouns are mass nouns may vary between languages. In English, mass nouns are characterized by the impossibility of being directly modified by a numeral without specifying a unit of measurement and by the impossibility of being combined with an indefinite article (a or an). Thus, the mass noun "water" is quantified as "20 litres of water" while the count noun "chair" is quantified as "20 chairs". However, both mass and count nouns can be quantified in relative terms without unit specification (e.g., "so much water", "so many chairs").
Mass nouns have no concept of singular and plural, although in English they take singular verb forms. However, many mass nouns in English can be converted to count nouns, which can then be used in the plural to denote (for instance) more than one instance or variety of a certain sort of entity โ for example, "Many cleaning agents today are technically not soaps [i.e. types of soap], but detergents," or "I drank about three beers [i.e. bottles or glasses of beer]".
Some nouns can be used indifferently as mass or count nouns, e.g., three cabbages or three heads of cabbage; three ropes or three lengths of rope. Some have different senses as mass and count nouns: paper is a mass noun as a material (three reams of paper, one sheet of paper), but a count noun as a unit of writing ("the students passed in their papers").
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- "Mass Noun" | 2023-04-21 | 65 Upvotes 85 Comments