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Comma Code
A comma code is a type of prefix-free code in which a comma, a particular symbol or sequence of symbols, occurs at the end of a code word and never occurs otherwise. This is an intuitive way to express arrays. For example, Fibonacci coding is a comma code in which the comma is 11. 11 and 1011 are valid Fibonacci code words, but 101, 0111, and 11011 are not. Examples * Unary coding, in which the comma is 0. This allows NULL values ( when the code and comma is a single 0, the value can be taken as a NULL or a 0 ). * Fibonacci coding, in which the comma is 11. * All Huffman codes can be converted to comma codes by prepending a 1 to the entire code and using a single 0 as a code and the comma. The definition of word being a number of symbols ending in a comma, the equivalent of a space character. * 50% commas in all data axiom - All implied data specifically variable length bijective data can be shown to be consisting of exactly 50% of commas. All data or suitably curated same-le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefix-free Code
A prefix code is a type of code system distinguished by its possession of the "prefix property", which requires that there is no whole code word in the system that is a prefix (initial segment) of any other code word in the system. It is trivially true for fixed-length code, so only a point of consideration in variable-length code. For example, a code with code words has the prefix property; a code consisting of does not, because "5" is a prefix of "59" and also of "55". A prefix code is a uniquely decodable code: given a complete and accurate sequence, a receiver can identify each word without requiring a special marker between words. However, there are uniquely decodable codes that are not prefix codes; for instance, the reverse of a prefix code is still uniquely decodable (it is a suffix code), but it is not necessarily a prefix code. Prefix codes are also known as prefix-free codes, prefix condition codes and instantaneous codes. Although Huffman coding is just one of many alg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibonacci Coding
In mathematics and computing, Fibonacci coding is a universal code which encodes positive integers into binary code words. It is one example of representations of integers based on Fibonacci numbers. Each code word ends with "11" and contains no other instances of "11" before the end. The Fibonacci code is closely related to the ''Zeckendorf representation'', a positional numeral system that uses Zeckendorf's theorem and has the property that no number has a representation with consecutive 1s. The Fibonacci code word for a particular integer is exactly the integer's Zeckendorf representation with the order of its digits reversed and an additional "1" appended to the end. Definition For a number N\!, if d(0),d(1),\ldots,d(k-1),d(k)\! represent the digits of the code word representing N\! then we have: : N = \sum_^ d(i) F(i+2),\textd(k-1)=d(k)=1.\! where is the th Fibonacci number, and so is the th distinct Fibonacci number starting with 1,2,3,5,8,13,\ldots. The last bit d(k) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unary Coding
Unary coding, or the unary numeral system and also sometimes called thermometer code, is an entropy encoding that represents a natural number, ''n'', with a code of length ''n'' + 1 ( or ''n'' ), usually ''n'' ones followed by a zero (if ''natural number'' is understood as ''non-negative integer'') or with ''n'' − 1 ones followed by a zero (if ''natural number'' is understood as ''strictly positive integer''). For example 5 is represented as 111110 or 11110. Some representations use ''n'' or ''n'' − 1 zeros followed by a one. The ones and zeros are interchangeable without loss of generality. Unary coding is both a prefix-free code and a self-synchronizing code. Unary coding is an optimally efficient encoding for the following discrete probability distribution :\operatorname(n) = 2^\, for n=1,2,3,.... In symbol-by-symbol coding, it is optimal for any geometric distribution :\operatorname(n) = (k-1)k^\, for which ''k'' ≥ φ = 1.6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huffman Coding
In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code proceeds by means of Huffman coding, an algorithm developed by David A. Huffman while he was a Sc.D. student at MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes". The output from Huffman's algorithm can be viewed as a variable-length code table for encoding a source symbol (such as a character in a file). The algorithm derives this table from the estimated probability or frequency of occurrence (''weight'') for each possible value of the source symbol. As in other entropy encoding methods, more common symbols are generally represented using fewer bits than less common symbols. Huffman's method can be efficiently implemented, finding a code in time linear to the number of input weights if these weights are sorted. However, although opt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space (punctuation)
In writing, a space () is a blank area that separates words, sentences, syllables (in syllabification) and other written or printed glyphs (characters). Conventions for spacing vary among languages, and in some languages the spacing rules are complex. Inter-word spaces ease the reader's task of identifying words, and avoid outright ambiguities such as "now here" vs. "nowhere". They also provide convenient guides for where a human or program may start new lines. Typesetting can use spaces of varying widths, just as it can use graphic characters of varying widths. Unlike graphic characters, typeset spaces are commonly stretched in order to align text. The typewriter, on the other hand, typically has only one width for all characters, including spaces. Following widespread acceptance of the typewriter, some typewriter conventions influenced typography and the design of printed works. Computer representation of text facilitates getting around mechanical and physical limitations su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chen–Ho Encoding
Chen–Ho encoding is a memory-efficient alternate system of binary encoding for decimal digits. The traditional system of binary encoding for decimal digits, known as binary-coded decimal (BCD), uses four bits to encode each digit, resulting in significant wastage of binary data bandwidth (since four bits can store 16 states and are being used to store only 10), even when using packed BCD. The encoding reduces the storage requirements of two decimal digits (100 states) from 8 to 7 bits, and those of three decimal digits (1000 states) from 12 to 10 bits using only simple Boolean transformations avoiding any complex arithmetic operations like a base conversion. History In what appears to have been a multiple discovery, some of the concepts behind what later became known as Chen–Ho encoding were independently developed by Theodore M. Hertz in 1969 and by Tien Chi Chen () (1928–) in 1971. Hertz of Rockwell filed a patent for his encoding in 1969, which was granted in 1971. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz Encoding
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its frequency, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-synchronizing Code
In coding theory, especially in telecommunications, a self-synchronizing code is a uniquely decodable code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. Put another way, a set of strings (called "code words") over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring. Every self-synchronizing code is a prefix code, but not all prefix codes are self-synchronizing. Other terms for self-synchronizing code are synchronized codeBerstel et al (2010) p. 137 or, ambiguously, comma-free code.Berstel & Perrin (1985) p. 377 A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream; external synchronization is not required. Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
