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๐Ÿ”— Karnaugh map

๐Ÿ”— Mathematics

The Karnaugh map (KM or K-map) is a method of simplifying Boolean algebra expressions. Maurice Karnaugh introduced it in 1953 as a refinement of Edward Veitch's 1952 Veitch chart, which actually was a rediscovery of Allan Marquand's 1881 logical diagram aka Marquand diagram but with a focus now set on its utility for switching circuits. Veitch charts are therefore also known as Marquandโ€“Veitch diagrams, and Karnaugh maps as Karnaughโ€“Veitch maps (KV maps).

The Karnaugh map reduces the need for extensive calculations by taking advantage of humans' pattern-recognition capability. It also permits the rapid identification and elimination of potential race conditions.

The required Boolean results are transferred from a truth table onto a two-dimensional grid where, in Karnaugh maps, the cells are ordered in Gray code, and each cell position represents one combination of input conditions, while each cell value represents the corresponding output value. Optimal groups of 1s or 0s are identified, which represent the terms of a canonical form of the logic in the original truth table. These terms can be used to write a minimal Boolean expression representing the required logic.

Karnaugh maps are used to simplify real-world logic requirements so that they can be implemented using a minimum number of physical logic gates. A sum-of-products expression can always be implemented using AND gates feeding into an OR gate, and a product-of-sums expression leads to OR gates feeding an AND gate. Karnaugh maps can also be used to simplify logic expressions in software design. Boolean conditions, as used for example in conditional statements, can get very complicated, which makes the code difficult to read and to maintain. Once minimised, canonical sum-of-products and product-of-sums expressions can be implemented directly using AND and OR logic operators. Diagrammatic and mechanical methods for minimizing simple logic expressions have existed since at least the medieval times. More systematic methods for minimizing complex expressions began to be developed in the early 1950s, but until the mid to late 1980s the Karnaugh map was the most common used in practice.

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๐Ÿ”— Usenet โ€“ A worldwide distributed discussion system

๐Ÿ”— Internet ๐Ÿ”— Internet culture ๐Ÿ”— Linguistics ๐Ÿ”— Linguistics/Applied Linguistics

Usenet () is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980. Users read and post messages (called articles or posts, and collectively termed news) to one or more categories, known as newsgroups. Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to Internet forums that are widely used today. Discussions are threaded, as with web forums and BBSs, though posts are stored on the server sequentially. The name comes from the term "users network".

A major difference between a BBS or web forum and Usenet is the absence of a central server and dedicated administrator. Usenet is distributed among a large, constantly changing conglomeration of servers that store and forward messages to one another via "newsย feeds". Individual users may read messages from and post messages to a local server, which may be operated by anyone.

Usenet is culturally and historically significant in the networked world, having given rise to, or popularized, many widely recognized concepts and terms such as "FAQ", "flame", sockpuppet, and "spam". In the 1990s, before access to the Internet became commonly affordable, Usenet connections via Fidonet's dial-up BBS networks made long-distance or worldwide discussions and other communication widespread, not needing a server, just (local) telephone service.

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๐Ÿ”— Pi Day

๐Ÿ”— Mathematics ๐Ÿ”— Festivals

Pi Day is an annual celebration of the mathematical constant ฯ€ (pi). Pi Day is observed on March 14 (3/14 in the month/day format) since 3, 1, and 4 are the first three significant digits of ฯ€. In 2009, the United States House of Representatives supported the designation of Pi Day. UNESCO's 40th General Conference decided Pi Day as the International Day of Mathematics in November 2019.

Pi Approximation Day is observed on July 22 (22/7 in the day/month format), since the fraction โ€‹22โ„7 is a common approximation of ฯ€, which is accurate to two decimal places and dates from Archimedes.

Two Pi Day, also known as Tau Day for the mathematical constant Tau, is observed on June 28 (6/28 in the month/day format).

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๐Ÿ”— Esquivalience

๐Ÿ”— United States ๐Ÿ”— Books ๐Ÿ”— Reference works ๐Ÿ”— English Language

The New Oxford American Dictionary (NOAD) is a single-volume dictionary of American English compiled by American editors at the Oxford University Press.

NOAD is based upon the New Oxford Dictionary of English (NODE), published in the United Kingdom in 1998, although with substantial editing, additional entries, and the inclusion of illustrations. It is based on a corpus linguistics analysis of Oxford's 200 million word database of contemporary American English.

NOAD includes a diacritical respelling scheme to convey pronunciations, as opposed to the Gimson phonemic IPA system that is used in NODE.

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๐Ÿ”— Long-term nuclear waste warning messages

๐Ÿ”— Linguistics ๐Ÿ”— Energy ๐Ÿ”— Linguistics/Philosophy of language

Long-term nuclear waste warning messages are intended to deter human intrusion at nuclear waste repositories in the far future, within or above the order of magnitude of 10,000 years. Nuclear semiotics is an interdisciplinary field of research, first done by the American Human Interference Task Force in 1981.

A 1993 report from Sandia National Laboratories recommended that such messages be constructed at several levels of complexity. They suggested that the sites should include foreboding physical features which would immediately convey to future visitors that the site was both man-made and dangerous, as well as providing pictographic information attempting to convey some details of the danger, and written explanations for those able to read it.

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๐Ÿ”— Two capacitor paradox

๐Ÿ”— Electronics

The two capacitor paradox or capacitor paradox is a paradox, or counterintuitive thought experiment, in electric circuit theory. The thought experiment is usually described as follows: Two identical capacitors are connected in parallel with an open switch between them. One of the capacitors is charged with a voltage of V i {\displaystyle V_{i}} , the other is uncharged. When the switch is closed, some of the charge Q = C V i {\displaystyle Q=CV_{i}} on the first capacitor flows into the second, reducing the voltage on the first and increasing the voltage on the second. When a steady state is reached and the current goes to zero, the voltage on the two capacitors must be equal since they are connected together. Since they both have the same capacitance C {\displaystyle C} the charge will be divided equally between the capacitors so each capacitor will have a charge of Q 2 {\displaystyle {Q \over 2}} and a voltage of V f = Q 2 C = V i 2 {\displaystyle V_{f}={Q \over 2C}={V_{i} \over 2}} . At the beginning of the experiment the total initial energy W i {\displaystyle W_{i}} in the circuit is the energy stored in the charged capacitor:

W i = 1 2 C V i 2 {\displaystyle W_{i}={1 \over 2}CV_{i}^{2}} .

At the end of the experiment the final energy W f {\displaystyle W_{f}} is equal to the sum of the energy in the two capacitors

W f = 1 2 C V f 2 + 1 2 C V f 2 = C V f 2 = C ( V i 2 ) 2 = 1 4 C V i 2 = 1 2 W i {\displaystyle W_{f}={1 \over 2}CV_{f}^{2}+{1 \over 2}CV_{f}^{2}=CV_{f}^{2}=C({V_{i} \over 2})^{2}={1 \over 4}CV_{i}^{2}={1 \over 2}W_{i}}

Thus the final energy W f {\displaystyle W_{f}} is equal to half of the initial energy W i {\displaystyle W_{i}} . Where did the other half of the initial energy go?

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๐Ÿ”— Community Memory Terminal

๐Ÿ”— Internet culture

Community Memory (CM) was the first public computerized bulletin board system. Established in 1973 in Berkeley, California, it used an SDS 940 timesharing system in San Francisco connected via a 110 baud link to a teleprinter at a record store in Berkeley to let users enter and retrieve messages. Individuals could place messages in the computer and then look through the memory for a specific notice.

While initially conceived as an information and resource sharing network linking a variety of counter-cultural economic, educational, and social organizations with each other and the public, Community Memory was soon generalized to be an information flea market, by providing unmediated, two-way access to message databases through public computer terminals. Once the system became available, the users demonstrated that it was a general communications medium that could be used for art, literature, journalism, commerce, and social chatter.

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๐Ÿ”— Laws of Power: Machiavelli and Sun-Tzu brought up-to-date

๐Ÿ”— Books ๐Ÿ”— Business

The 48 Laws of Power (1998) is a non-fiction book by American author Robert Greene. The book is a bestseller, selling over 1.2 million copies in the United States, and is popular with prison inmates and celebrities.

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๐Ÿ”— Fittsโ€™s law

๐Ÿ”— Computing ๐Ÿ”— Cognitive science ๐Ÿ”— Computing/Computer science ๐Ÿ”— Humanโ€“Computer Interaction

Fitts's law (often cited as Fitts' law) is a predictive model of human movement primarily used in humanโ€“computer interaction and ergonomics. This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target. Fitts's law is used to model the act of pointing, either by physically touching an object with a hand or finger, or virtually, by pointing to an object on a computer monitor using a pointing device.

Fitts's law has been shown to apply under a variety of conditions; with many different limbs (hands, feet, the lower lip, head-mounted sights), manipulanda (input devices), physical environments (including underwater), and user populations (young, old, special educational needs, and drugged participants).

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๐Ÿ”— Delphi

๐Ÿ”— Computing ๐Ÿ”— Computing/Software

Delphi is an event-driven programming language based on Object Pascal and an associated integrated development environment (IDE) for rapid application development of desktop, mobile, web, and console software, currently developed and maintained by Embarcadero Technologies.

Delphi's compilers generate native code for Microsoft Windows, macOS, iOS, Android and Linux (x64 only). Since 2016, there have been new releases of Delphi every six months, with new platforms being added approximately every second release.

Delphi includes a code editor, a visual designer, an integrated debugger, a source code control component, and support for third-party plugins. The code editor features Code Insight (code completion), Error Insight (real-time error-checking), and refactoring. The visual forms designer has traditionally used Visual Component Library (VCL) for native Windows development, but the FireMonkey (FMX) platform was later added for cross-platform development. Database support in Delphi is very strong. A Delphi project of a million lines of code can compile in a few seconds โ€“ one benchmark compiled 170,000 lines per second.

Delphi was originally developed by Borland as a rapid application development tool for Windows as the successor of Turbo Pascal. Delphi added full object-oriented programming to the existing language, and since then the language has grown to support generics and anonymous methods, and native Component Object Model (COM) support. In 2006, Borlandโ€™s developer tools section was transferred from Borland to a wholly owned subsidiary known as CodeGear, which was sold to Embarcadero Technologies in 2008. In 2015, Embarcadero was purchased by Idera Software, but the Embarcadero mark was retained for the developer tools division.

Delphi and its C++ counterpart, C++Builder, are interoperable. They share many core components, notably the IDE, VCL, and much of the runtime library. In addition, they can be used jointly in a project. For example, C++Builder 6 and later can consume Delphi source code and C++ in one project, while packages compiled with C++Builder can be used from within Delphi. In 2007, the products were released jointly as RADย Studio, a shared host for Delphi and C++Builder, which can be purchased with either or both.

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