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Zone File
A Domain Name System (DNS) zone file is a text file that describes a DNS zone. A DNS zone is a subset, often a single domain, of the hierarchical domain name structure of the DNS. The zone file contains mappings between domain names and IP addresses and other resources, organized in the form of text representations of resource records (RR). A zone file may be either a DNS master file, authoritatively describing a zone, or it may be used to list the contents of a DNS cache.
  • 537
  • 13 Oct 2022
Topic Review
Zermelo's Theorem (Game Theory)
In game theory, Zermelo's theorem is a theorem about finite two-person games of perfect information in which the players move alternately and in which chance does not affect the decision making process. It says that if the game cannot end in a draw, then one of the two players must have a winning strategy (i.e. can force a win). An alternate statement is that for a game meeting all of these conditions except the condition that a draw is now possible, then either the first-player can force a win, or the second-player can force a win, or both players can force a draw. The theorem is named after Ernst Zermelo, a German mathematician and logician, who proved the theorem for the example game of chess in 1913.
  • 563
  • 15 Nov 2022
Topic Review
Yuktibhāṣā
Yuktibhāṣā (Malayalam: യുക്തിഭാഷ, lit. 'Rationale'), also known as Gaṇita-yukti-bhāṣā:xxi and Gaṇitanyāyasaṅgraha (Compendium of Astronomical Rationale), is a major treatise on mathematics and astronomy, written by the India n astronomer Jyesthadeva of the Kerala school of mathematics around 1530. The treatise, written in Malayalam, is a consolidation of the discoveries by Madhava of Sangamagrama, Nilakantha Somayaji, Parameshvara, Jyeshtadeva, Achyuta Pisharati, and other astronomer-mathematicians of the Kerala school. It also exists in a Sanskrit version, with unclear author and date, composed as a rough translation of the Malayalam original. The work contains proofs and derivations of the theorems that it presents. Modern historians used to assert, based on the works of Indian mathematics that first became available, that early Indian scholars in astronomy and computation lacked in proofs, but Yuktibhāṣā demonstrates otherwise. Some of its important topics include the infinite series expansions of functions; power series, including of π and π/4; trigonometric series of sine, cosine, and arctangent; Taylor series, including second and third order approximations of sine and cosine; radii, diameters and circumferences; and tests of convergence. Yuktibhāṣā mainly gives rationale for the results in Nilakantha's Tantra Samgraha. It is considered an early text on the ideas of calculus, predating Newton and Leibniz by centuries. The treatise was largely unnoticed outside India, as it was written in the local language of Malayalam. In modern times, due to wider international cooperation in mathematics, the wider world has taken notice of the work. For example, both Oxford University and the Royal Society of Great Britain have given attribution to pioneering mathematical theorems of Indian origin that predate their Western counterparts.
  • 639
  • 21 Nov 2022
Topic Review
Yao's Millionaires' Problem
Yao's Millionaires' problem is a secure multi-party computation problem which was introduced in 1982 by computer scientist and computational theorist Andrew Yao. The problem discusses two millionaires, Alice and Bob, who are interested in knowing which of them is richer without revealing their actual wealth. This problem is analogous to a more general problem where there are two numbers [math]\displaystyle{ a }[/math] and [math]\displaystyle{ b }[/math] and the goal is to determine whether the inequality [math]\displaystyle{ a \geq b }[/math] is true or false without revealing the actual values of [math]\displaystyle{ a }[/math] and [math]\displaystyle{ b }[/math]. The Millionaires' Problem is an important problem in cryptography, the solution of which is used in e-commerce and data mining. Commercial applications sometimes have to compare numbers which are confidential and whose security is important. Many solutions have been introduced for the problem, among which the first solution, presented by Yao himself, was exponential in time and space.
  • 2.6K
  • 15 Nov 2022
Topic Review
Yan Tan Tethera
Yan Tan Tethera is a sheep-counting rhyme/system traditionally used by shepherds in Northern England and earlier in some other parts of Britain. Until the Industrial Revolution, the use of traditional number systems was common among shepherds, especially in the fells of the Lake District. The Yan Tan Tethera system was also used for counting stitches in knitting. The words derive from a Brythonic Celtic language. Though most of these number systems fell out of use by 1910, some are still in use. The word yan or yen for "one" in some northern English dialects generally represents a regular development in Northern English in which the Old English long vowel /ɑː/ was broken into /ie/, /ia/ and so on. This explains the shift to yan and ane from the Old English ān, which is itself derived from the Proto-Germanic *ainaz. Another example of this development is the Northern English word for "home", hame, which has forms such as hyem, yem and yam all deriving from the Old English hām.
  • 2.5K
  • 20 Nov 2022
Topic Review
Yakuza Kenzan
Ryū ga Gotoku Kenzan! (Japanese: 龍が如く 見参！, "Like a Dragon Arrives!"), unofficially known as Yakuza Kenzan, is a jidaigeki-themed spin-off game in the Yakuza series. The game was developed and published by Sega for PlayStation 3. It was unveiled at the Tokyo Game Show 2007 and released in 2008. A second Yakuza series spin-off set in samurai era, Ryū ga Gotoku Ishin!, was released in 2014 on both the PlayStation 3 and the PlayStation 4 systems. Ishin! is set two centuries later than Kenzan!, hence the plots are not related to each other since both games focus on different characters, the historical figures of Sakamoto Ryōma (1836-1867) and Miyamoto Musashi (1584-1645) respectively.
  • 1.5K
  • 20 Oct 2022
Topic Review
Yahoo! Messenger Protocol
The Yahoo! Messenger Protocol (YMSG) is the underlying network protocol used by the Yahoo! Messenger instant messaging client. Yahoo! Instant Messager supports many features beyond just messaging, including off-line messaging, file transfer, chat, conferencing, voice chat, webcams and avatars.
  • 1.7K
  • 07 Nov 2022
Topic Review
XTS-400
The XTS-400 is a multilevel secure computer operating system. It is multiuser and multitasking that uses multilevel scheduling in processing data and information. It works in networked environments and supports Gigabit Ethernet and both IPv4 and IPv6. The XTS-400 is a combination of Intel x86 hardware and the Secure Trusted Operating Program (STOP) operating system. XTS-400 was developed by BAE Systems, and originally released as version 6.0 in December 2003. STOP provides high-assurance security and was the first general-purpose operating system with a Common Criteria assurance level rating of EAL5 or above. The XTS-400 can host, and be trusted to separate, multiple, concurrent data sets, users, and networks at different sensitivity levels. The XTS-400 provides both an untrusted environment for normal work and a trusted environment for administrative work and for privileged applications. The untrusted environment is similar to traditional Unix environments. It provides binary compatibility with Linux applications running most Linux commands and tools as well as most Linux applications without the need for recompiling. This untrusted environment includes an X Window System GUI, though all windows on a screen must be at the same sensitivity level. To support the trusted environment and various security features, STOP provides a set of proprietary APIs to applications. In order to develop programs that use these proprietary APIs, a special software development environment (SDE) is needed. The SDE is also needed in order to port some complicated Linux/Unix applications to the XTS-400. A new version of the STOP operating system, STOP 7 has since been introduced, with claims to have improved performance and new features such as RBAC.
  • 300
  • 08 Oct 2022
Topic Review
Xlib
Xlib (also known as libX11) is an X Window System protocol client library written in the C programming language. It contains functions for interacting with an X server. These functions allow programmers to write programs without knowing the details of the X protocol. Few applications use Xlib directly; rather, they employ other libraries that use Xlib functions to provide widget toolkits: Xlib appeared around 1985, and is used in GUIs for many Unix-like operating systems. A re-implementation of Xlib was introduced in 2007 using XCB.
  • 494
  • 24 Oct 2022
Topic Review
Xi (Alternate Reality Game)
Xi (UK: /ˈsaɪ/ or US: /ˈzaɪ/) was the world's first console-based and virtual world-based alternate reality game. It was a one-time-only play, unfolding in real time, and only available on the PlayStation 3 through the social gaming network, PlayStation Home. The game was an adventure to help find "Jess" and the meaning of Xi by collecting fragments and butterflies found in a series of secret areas in Home that changed frequently. The game also challenged the users to search for clues in the real world. The game was created by nDreams who released several spaces for Xi. The game was promoted through a teaser campaign of clues and hints during the month prior to its release on March 23, 2009. The clues were hidden in the Menu Pad and videos in the central meeting point. The game lasted a total of 12 weeks from its release. Xi and all of the corresponding spaces were exclusive to the European and North American versions of PlayStation Home, though there were also websites, videos, printed media and live events which were accessible to anyone. In September 2009, it was reported that the number of visits to the Xi spaces, including the ones after Xi's completion, had exceeded 5 million visits. A sequel, Xi: Continuum, was released in December 2012.
  • 317
  • 30 Oct 2022
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