New Articles (Page 287)
To stay up to date you can also follow on Mastodon.
π Andreas Raab passed away
The Squeak programming language is a dialect of Smalltalk. It is object-oriented, class-based, and reflective.
It was derived directly from Smalltalk-80 by a group at Apple Computer that included some of the original Smalltalk-80 developers. Its development was continued by the same group at Walt Disney Imagineering, where it was intended for use in internal Disney projects. Later on the group moved on to be supported by HP labs, SAP Labs and most recently Y Combinator.
Squeak is cross-platform. Programs produced on one platform run bit-identical on all other platforms, and versions are available for many platforms including the obvious Windows/macOS/linux versions. The Squeak system includes code for generating a new version of the virtual machine (VM) on which it runs. It also includes a VM simulator written in Squeak. For these reasons, it is easily ported.
Discussed on
- "Andreas Raab passed away" | 2013-01-17 | 19 Upvotes 2 Comments
π Wikipedia entry for Aaron Swartz-founded PAC was deleted the day he died
Demand Progress is an internet activist-related entity encompassing a 501(c)4 arm sponsored by the 1630 Fund and a 501(c)3 arm sponsored by the New Venture Fund. It specializes in online-intensive and other grassroots activism to support Internet freedom, civil liberties, transparency, and human rights, and in opposition to censorship and corporate control of government. The organization was founded through a petition in opposition to the Combating Online Infringement and Counterfeits Act, sparking the movement that eventually defeated COICA's successor bills, the Stop Online Piracy Act and the PROTECT IP Act, two highly controversial pieces of United States legislation.
The organization has continued to fight for such causes in the wake of the successful shelving of these two acts. Demand Progress has also played key roles in forwarding the passage of net neutrality rules, blocking expansion of the Computer Fraud and Abuse Act, under which co-founder Aaron Swartz was indicted, and other key legislative efforts. Estimated membership numbers in early 2015 weigh in at over two million. As of late 2013, the organization encompasses the Demand Progress, Rootstrikers and Watchdog.net wings/brands.
Discussed on
- "Wikipedia entry for Aaron Swartz-founded PAC was deleted the day he died" | 2013-01-13 | 26 Upvotes 5 Comments
π Judy arrays are patented
In computer science, a Judy array is a data structure implementing a type of associative array with high performance and low memory usage. Unlike most other key-value stores, Judy arrays use no hashing, leverage compression on their keys (which may be integers or strings), and can efficiently represent sparse data, that is, they may have large ranges of unassigned indices without greatly increasing memory usage or processing time. They are designed to remain efficient even on structures with sizes in the peta-element range, with performance scaling on the order of O(log n). Roughly speaking, Judy arrays are highly optimized 256-ary radix trees.
Judy trees are usually faster than AVL trees, B-trees, hash tables and skip lists because they are highly optimized to maximize usage of the CPU cache. In addition, they require no tree balancing and no hashing algorithm is used.
The Judy array was invented by Douglas Baskins and named after his sister.
Discussed on
- "Judy arrays are patented" | 2013-01-11 | 42 Upvotes 56 Comments
π Bernoulli discovered e by studying a question about compound interest
The number e is a mathematical constant approximately equal to 2.71828 and is the base of the natural logarithm: the unique number whose natural logarithm is equal to one. It is the limit of (1 + 1/n)n as n approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series
The constant can be characterized in many different ways. For example, it can be defined as the unique positive number a such that the graph of the function y = ax has unit slope at x = 0. The function f(x) = ex is called the (natural) exponential function, and is the unique exponential function equal to its own derivative. The natural logarithm, or logarithm to base e, is the inverse function to the natural exponential function. The natural logarithm of a number k > 1 can be defined directly as the area under the curve y = 1/x between x = 1 and x = k, in which case e is the value of k for which this area equals one (see image). There are alternative characterizations.
e is sometimes called Euler's number after the Swiss mathematician Leonhard Euler (not to be confused with Ξ³, the EulerβMascheroni constant, sometimes called simply Euler's constant), or as Napier's constant. However, Euler's choice of the symbol e is said to have been retained in his honor. The constant was discovered by the Swiss mathematician Jacob Bernoulli while studying compound interest.
The number e has eminent importance in mathematics, alongside 0, 1, Ο, and i. All five of these numbers play important and recurring roles across mathematics, and these five constants appear in one formulation of Euler's identity. Like the constant Ο, e is also irrational (i.e. it cannot be represented as ratio of integers) and transcendental (i.e. it is not a root of any non-zero polynomial with rational coefficients). The numerical value of e truncated to 50 decimal places is
Discussed on
- "Bernoulli discovered e by studying a question about compound interest" | 2012-12-26 | 51 Upvotes 16 Comments
π The deadliest school massacre in US history occurred in 1927
The Bath School disaster, also known as the Bath School massacre, was a series of violent attacks perpetrated by Andrew Kehoe on MayΒ 18, 1927, in Bath Township, Michigan. The attacks killed 38Β elementary schoolchildren and 6Β adults, and injured at least 58Β other people. Prior to his timed explosives going off at the Bath Consolidated School building, Kehoe had murdered his wife, Nellie Price Kehoe, and firebombed his farm. Arriving at the site of the school explosion, Kehoe died when he detonated explosives concealed in his truck.
Kehoe, the 55-year-old school board treasurer, was angered by increased taxes and his defeat in the April 5, 1926, election for township clerk. He was thought by locals to have planned his "murderous revenge" after that public defeat. Kehoe had a reputation for difficulty on the school board and in personal dealings. In addition, he was notified that his mortgage was going to be foreclosed upon in June 1926. For much of the next year until May 1927, Kehoe purchased explosives. He secretly hid them on his property and under the school.
On May 18, 1927, Kehoe then set off almost simultaneous explosions at his farmstead and at the Bath Consolidated School. His explosives destroyed the farm's buildings and ripped through the north wing of the Bath Consolidated School building. As rescuers began working at the school, Kehoe drove up to the schoolyard and detonated dynamite inside his shrapnel-filled truck. The truck explosion killed Kehoe and several others nearby. Bystanders were injured. During the rescue and recovery efforts, searchers discovered an additional 500Β pounds (230Β kg) of unexploded dynamite and pyrotol in the south wing of the school that was set to explode at the same time as the initial explosions in the north wing; Kehoe had apparently intended to destroy the entire school and kill everyone in it.
Discussed on
- "The deadliest school massacre in US history occurred in 1927" | 2012-12-17 | 19 Upvotes 5 Comments
π Intellipedia (U.S. intelligence agencies' internal wiki)
Intellipedia is an online system for collaborative data sharing used by the United States Intelligence Community (IC). It was established as a pilot project in late 2005 and formally announced in April 2006. Intellipedia consists of three wikis running on the separate JWICS (Intellipedia-TS), SIPRNet (Intellipedia-S), and DNI-U (Intellipedia-U) networks. The levels of classification allowed for information on the three wikis are Top Secret Sensitive Compartmented Information (TS SCI), Secret (S), and Sensitive But Unclassified (SBU or FOUO) information, respectively. Each of the wikis is used by individuals with appropriate clearances from the 16 agencies of the US intelligence community and other national-security related organizations, including Combatant Commands and other federal departments. The wikis are not open to the public.
Intellipedia is a project of the Office of the Director of National Intelligence (ODNI) Intelligence Community Enterprise Services (ICES) office headquartered in Fort Meade, Maryland. It includes information on the regions, people, and issues of interest to the communities using its host networks. Intellipedia uses MediaWiki, the same software used by the Wikipedia free-content encyclopedia project. To the contrary of mainstream Wikipedia, its intelligence analogue encourages editing that incorporates personal points of view regardless of rank as it was decided that, "much of the self-corrective knowledge in the Intelligence Community resides in personal points of view," and that, "not all good ideas originate at the top."
The Secret version connected to SIPRNet predominantly serves Department of Defense and the Department of State personnel, many of whom do not use the Top Secret JWICS network on a day-to-day basis. Users on unclassified networks can access Intellipedia from remote terminals outside their workspaces via a VPN, in addition to their normal workstations. Open Source Intelligence (OSINT) users share information on the unclassified Intelink-U wiki.
π Shakespeare (programming language)
The Shakespeare Programming Language (SPL) is an esoteric programming language designed by Jon Γ slund and Karl HasselstrΓΆm. Like the Chef programming language, it is designed to make programs appear to be something other than programs; in this case, Shakespearean plays.
A character list in the beginning of the program declares a number of stacks, naturally with names like "Romeo" and "Juliet". These characters enter into dialogue with each other in which they manipulate each other's topmost values, push and pop each other, and do I/O. The characters can also ask each other questions which behave as conditional statements. On the whole, the programming model is very similar to assembly language but much more verbose.
Discussed on
- "Shakespeare (programming language)" | 2012-12-12 | 34 Upvotes 10 Comments
- "Shakespeare programming language" | 2011-10-29 | 36 Upvotes 8 Comments
π CipherSaber - A 'political' encryption cipher
CipherSaber is a simple symmetric encryption protocol based on the RC4 stream cipher. Its goals are both technical and political: it gives reasonably strong protection of message confidentiality, yet it's designed to be simple enough that even novice programmers can memorize the algorithm and implement it from scratch. According to the designer, a CipherSaber version in the QBASIC programming language takes just sixteen lines of code. Its political aspect is that because it's so simple, it can be reimplemented anywhere at any time, and so it provides a way for users to communicate privately even if government or other controls make distribution of normal cryptographic software completely impossible.
Discussed on
- "CipherSaber - A 'political' encryption cipher" | 2012-12-11 | 42 Upvotes 14 Comments
π Nomic
Nomic is a game created in 1982 by philosopher Peter Suber in which the rules of the game include mechanisms for the players to change those rules, usually beginning through a system of democratic voting.
Nomic is a game in which changing the rules is a move. In that respect it differs from almost every other game. The primary activity of Nomic is proposing changes in the rules, debating the wisdom of changing them in that way, voting on the changes, deciding what can and cannot be done afterwards, and doing it. Even this core of the game, of course, can be changed.
The initial ruleset was designed by Peter Suber, and first published in Douglas Hofstadter's column Metamagical Themas in Scientific American in June 1982. The column discussed Suber's then-upcoming book, The Paradox of Self-Amendment, which was published some years later. Nomic now refers to many games, all based on the initial ruleset.
The game is in some ways modeled on modern government systems. It demonstrates that in any system where rule changes are possible, a situation may arise in which the resulting laws are contradictory or insufficient to determine what is in fact legal. Because the game models (and exposes conceptual questions about) a legal system and the problems of legal interpretation, it is named after Ξ½ΟΞΌΞΏΟ (nomos), Greek for "law".
While the victory condition in Suber's initial ruleset is the accumulation of 100 points by the roll of dice, he once said that "this rule is deliberately boring so that players will quickly amend it to please themselves". Players can change the rules to such a degree that points can become irrelevant in favor of a true currency, or make victory an unimportant concern. Any rule in the game, including the rules specifying the criteria for winning and even the rule that rules must be obeyed, can be changed. Any loophole in the ruleset, however, may allow the first player to discover it the chance to pull a "scam" and modify the rules to win the game. Complicating this process is the fact that Suber's initial ruleset allows for the appointment of judges to preside over issues of rule interpretation.
Discussed on
- "Nomic" | 2012-12-08 | 242 Upvotes 84 Comments
- "Nomic: a game in which changing the rules is a move" | 2009-06-21 | 22 Upvotes 9 Comments
π Valid Email Addresses
An email address identifies an email box to which email messages are delivered. A wide variety of formats were used in early email systems, but only a single format is used today, following the specifications developed for Internet mail systems since the 1980s. This article uses the term email address to refer to the addr-spec defined in RFC 5322, not to the address that is commonly used; the difference is that an address may contain a display name, a comment, or both.
An email address such as John.Smith@example.com is made up of a local-part, an @ symbol, then a case-insensitive domain. Although the standard requires the local part to be case-sensitive, it also urges that receiving hosts deliver messages in a case-independent fashion, e.g., that the mail system at example.com treat John.Smith as equivalent to john.smith; some mail systems even treat them as equivalent to johnsmith. Mail systems often limit their users' choice of name to a subset of the technically valid characters, and in some cases also limit which addresses it is possible to send mail to.
With the introduction of internationalized domain names, efforts are progressing to permit non-ASCII characters in email addresses.
Discussed on
- "Valid Email Addresses" | 2012-11-30 | 50 Upvotes 59 Comments