Topic: Computing (Page 46)

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πŸ”— A graph is moral if two nodes that have a common child are married

πŸ”— Computing πŸ”— Mathematics πŸ”— Statistics πŸ”— Robotics

In graph theory, a moral graph is used to find the equivalent undirected form of a directed acyclic graph. It is a key step of the junction tree algorithm, used in belief propagation on graphical models.

The moralized counterpart of a directed acyclic graph is formed by adding edges between all pairs of non-adjacent nodes that have a common child, and then making all edges in the graph undirected. Equivalently, a moral graph of a directed acyclic graph G is an undirected graph in which each node of the original G is now connected to its Markov blanket. The name stems from the fact that, in a moral graph, two nodes that have a common child are required to be married by sharing an edge.

Moralization may also be applied to mixed graphs, called in this context "chain graphs". In a chain graph, a connected component of the undirected subgraph is called a chain. Moralization adds an undirected edge between any two vertices that both have outgoing edges to the same chain, and then forgets the orientation of the directed edges of the graph.

πŸ”— Ruby (Programming Language)

πŸ”— Computing πŸ”— Computer science πŸ”— Computing/Software πŸ”— Computing/Free and open-source software

Ruby is an interpreted, high-level, general-purpose programming language which supports multiple programming paradigms. It was designed with an emphasis on programming productivity and simplicity. In Ruby, everything is an object, including primitive data types. It was developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan.

Ruby is dynamically typed and uses garbage collection and just-in-time compilation. It supports multiple programming paradigms, including procedural, object-oriented, and functional programming. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, BASIC, Java and Lisp.

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πŸ”— PNG can be Animated Wait WTF? APNG file format

πŸ”— Computing πŸ”— Animation

Animated Portable Network Graphics (APNG) is a file format which extends the Portable Network Graphics (PNG) specification to permit animated images that work similarly to animated GIF files, while supporting 24 or 48-bit images and full alpha transparency not available for GIFs. It also retains backward compatibility with non-animated PNG files.

The first frame of an APNG file is stored as a normal PNG stream, so most standard PNG decoders are able to display the first frame of an APNG file. The frame speed data and extra animation frames are stored in extra chunks (as provided for by the original PNG specification). APNG competed with Multiple-image Network Graphics (MNG), a comprehensive format for bitmapped animations which was created by the same team as PNG and is obsolete. APNG's advantage was the smaller library size and compatibility with older PNG implementations.

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πŸ”— Fog Computing

πŸ”— Computing

Fog computing or fog networking, also known as fogging, is an architecture that uses edge devices to carry out a substantial amount of computation, storage, and communication locally and routed over the internet backbone.

πŸ”— Fravia

πŸ”— Biography πŸ”— Computing

Francesco Vianello (30 August 1952 – 3 May 2009), better known by his nickname Fravia (sometimes +Fravia or Fravia+), was a software reverse engineer, and hacker, known for his web archive of reverse engineering techniques and papers. He is also known for his work on steganography. He had taught on subjects such as data mining, anonymity, stalking, klebing, advertisement reversing and ad-busting.

Fravia spoke six languages (including Latin) and had a degree in the history of the early Middle Ages. He was an expert in linguistics-related informatics. For five years he made available a large quantity of material related to reverse engineering through his website, which also hosted the advice of reverse engineering experts, known as reversers, who provided tutorials and essays on how to hack software code as well as advice related to the assembly and disassembly of applications, and software protection reversing.

Fravia was a professor at the High Cracking University (+HCU), founded by Old Red Cracker (+ORC), a legendary figure in reverse engineering, to conduct research into Reverse Code Engineering. The addition of the "+" sign in front of the nickname of a reverser signified membership in the +HCU. His website was known as "+Fravia's Pages of Reverse Engineering" and he used it to challenge programmers as well as the wider society to "reverse engineer" the "brainwashing of a corrupt and rampant materialism". In its heyday, his website was receiving millions of visitors per year and its influence was "widespread".

His web presence dates from 1995 when he first got involved in research related to reverse code engineering (RCE). In 2000 he changed his focus and concentrated on advanced internet search methods and the reverse engineering of search engine code.

His websites "www.fravia.com" and "www.searchlores.org" contained a large amount of specialised information related to data mining. His website "www.searchlores.org" has been called a "very useful instrument for searching the web", and his "www.fravia.com" site has been described as "required reading for any spy wanting to go beyond simple Google searches."

πŸ”— Han unification

πŸ”— Computing πŸ”— China πŸ”— East Asia πŸ”— Writing systems πŸ”— Hong Kong

Han unification is an effort by the authors of Unicode and the Universal Character Set to map multiple character sets of the so-called CJK languages into a single set of unified characters. Han characters are a common feature of written Chinese (hanzi), Japanese (kanji), and Korean (hanja).

Modern Chinese, Japanese and Korean typefaces typically use regional or historical variants of a given Han character. In the formulation of Unicode, an attempt was made to unify these variants by considering them different glyphs representing the same "grapheme", or orthographic unit, hence, "Han unification", with the resulting character repertoire sometimes contracted to Unihan.

Unihan can also refer to the Unihan Database maintained by the Unicode Consortium, which provides information about all of the unified Han characters encoded in the Unicode Standard, including mappings to various national and industry standards, indices into standard dictionaries, encoded variants, pronunciations in various languages, and an English definition. The database is available to the public as text files and via an interactive website. The latter also includes representative glyphs and definitions for compound words drawn from the free Japanese EDICT and Chinese CEDICT dictionary projects (which are provided for convenience and are not a formal part of the Unicode Standard).

πŸ”— ReFS

πŸ”— Computing πŸ”— Microsoft Windows πŸ”— Microsoft Windows/Computing πŸ”— Microsoft

Resilient File System (ReFS), codenamed "Protogon", is a Microsoft proprietary file system introduced with Windows Server 2012 with the intent of becoming the "next generation" file system after NTFS.

ReFS was designed to overcome problems that had become significant over the years since NTFS was conceived, which are related to how data storage requirements had changed. The key design advantages of ReFS include automatic integrity checking and data scrubbing, removal of the need for running chkdsk, protection against data degradation, built-in handling of hard disk drive failure and redundancy, integration of RAID functionality, a switch to copy/allocate on write for data and metadata updates, handling of very long paths and filenames, and storage virtualization and pooling, including almost arbitrarily sized logical volumes (unrelated to the physical sizes of the used drives).

These requirements arose from two major changes in storage systems and usage – the size of storage in use (large or massive arrays of multi-terabyte drives now being fairly common), and the need for continual reliability. As a result, the file system needs to be self-repairing (to prevent disk checking from being impractically slow or disruptive), along with abstraction or virtualization between physical disks and logical volumes.

ReFS was initially added to Windows Server 2012 only, with the aim of gradual migration to consumer systems in future versions; this was achieved as of Windows 8.1. The initial versions removed some NTFS features, such as disk quotas, alternate data streams, and extended attributes. Some of these were re-implemented in later versions of ReFS.

In early versions (2012–2013), ReFS was similar to or slightly faster than NTFS in most tests, but far slower when full integrity checking was enabled, a result attributed to the relative newness of ReFS. Pre-release concerns were also voiced by one blogger over Storage Spaces, the storage system designed to underpin ReFS, which reportedly could fail in a manner that prevented ReFS from recovering automatically.

The ability to create ReFS volumes was removed in Windows 10's 2017 Fall Creators Update for all editions except Enterprise and Pro for Workstations.

The cluster size of a ReFS volume is either 4 KiB or 64 KiB.

πŸ”— Yo-yo problem

πŸ”— Computing πŸ”— Computing/Software

In software development, the yo-yo problem is an anti-pattern that occurs when a programmer has to read and understand a program whose inheritance graph is so long and complicated that the programmer has to keep flipping between many different class definitions in order to follow the control flow of the program. It often happens in object-oriented programming. The term comes from comparing the bouncing attention of the programmer to the up-down movement of a toy yo-yo. Taenzer, Ganti, and Podar described the problem by name, explaining: "Often we get the feeling of riding a yoyo when we try to understand one of these message trees."

Most practices of object-oriented programming recommend keeping the inheritance graph as shallow as possible, in part to avoid this problem. The use of composition instead of inheritance is also strongly preferred, although this still requires that a programmer keep multiple class definitions in mind at once.

More generally, the yo-yo problem can also refer to any situation where a person must keep flipping between different sources of information in order to understand a concept.

Object-oriented design techniques such as documenting layers of the inheritance hierarchy can reduce the effect of this problem, as they collect in one place the information that the programmer is required to understand.

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πŸ”— Viterbi Algorithm

πŸ”— Computing πŸ”— Robotics

The Viterbi algorithm is a dynamic programming algorithm for obtaining the maximum a posteriori probability estimate of the most likely sequence of hidden statesβ€”called the Viterbi pathβ€”that results in a sequence of observed events, especially in the context of Markov information sources and hidden Markov models (HMM).

The algorithm has found universal application in decoding the convolutional codes used in both CDMA and GSM digital cellular, dial-up modems, satellite, deep-space communications, and 802.11 wireless LANs. It is now also commonly used in speech recognition, speech synthesis, diarization, keyword spotting, computational linguistics, and bioinformatics. For example, in speech-to-text (speech recognition), the acoustic signal is treated as the observed sequence of events, and a string of text is considered to be the "hidden cause" of the acoustic signal. The Viterbi algorithm finds the most likely string of text given the acoustic signal.

πŸ”— .XIP

πŸ”— Computing πŸ”— Computing/Computer Security

An .XIP file is a XAR archive which can be digitally signed for integrity. The .XIP file format was introduced in OS X 10.9, along with Apple's release of Swift. .XIP allows for a digital signature to be applied and verified on the receiving system before the archive is expanded. When a XIP file is opened (by double-clicking), Archive Utility will automatically expand it (but only if the digital signature is intact).

Apple has reserved the right to use the .XIP file format exclusively, removing it from public use since release. Starting with macOS Sierra, only .XIP archives signed by Apple will be expanded. Developers who had been using .XIP archives were required to move to using signed installer packages or disk images.