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Numbering
There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a primary key of a database management system table, whose table definitions require a database design. In computability theory, the simplest numbering scheme is the assignment of natural numbers to a set of objects such as functions, rational numbers, graphs, or words in some formal language. A numbering can be used to transfer the idea of computability and related concepts, which are originally defined on the natural numbers using computable functions, to these different types of objects. A simple extension is to assign cardinal numbers to physical objects according to the choice of some base of reference and of measurement units for counting or measuring these objects within a given precision. In such case, numbering is a kind of classification, i.e. assigning a numeric pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Numbering Plan
The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international calling code ''1''. Some North American countries, most notably Mexico, do not participate in the NANP. The NANP was originally devised in the 1940s by the American Telephone and Telegraph Company (AT&T) for the Bell System and the independent telephone operators in North America. The goal was to unify the diverse local numbering plans that had been established in the preceding decades and prepare the continent for direct-dialing of calls by customers without the involvement of telephone operators. AT&T continued to administer the numbering plan until the breakup of the Bell System, when administration was delegated to the North American Numbering Plan Administrator (NANPA), a service that has been procured from the private sector by the Fede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Numbering Plan
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone number A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices f ...s to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks. For public numbering systems, geographic location typically plays a role in the sequence of numbers assigned to each telephone subscriber. Many numbering plan administrators subdivide their territory of service into geographic regions designated by a prefix, often called an area code or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numbering (computability Theory)
In computability theory a numbering is the assignment of natural numbers to a set of objects such as functions, rational numbers, graphs, or words in some formal language. A numbering can be used to transfer the idea of computability and related concepts, which are originally defined on the natural numbers using computable functions, to these different types of objects. Common examples of numberings include Gödel numberings in first-order logic, the description numbers that arise from universal Turing machines and admissible numberings of the set of partial computable functions. Definition and examples A numbering of a set S is a surjective partial function from \mathbb to ''S'' (Ershov 1999:477). The value of a numbering ''ν'' at a number ''i'' (if defined) is often written ''ν''''i'' instead of the usual \nu(i) \!. Examples of numberings include: * The set of all finite subsets of \mathbb has a numbering \gamma , defined so that \gamma(0) = \emptyset and so that, for eac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australian Telephone Numbering Plan
The Australian telephone numbering plan describes the allocation of phone numbers in Australia. It has changed many times, the most recent major reorganisation by the Australian Communications & Media Authority taking place between 1994 and 1998. Overview For landline telephony, Australia is now geographically divided into four large areas, three of which cover more than one state and/or territory. All local telephone numbers within these four areas are of eight digits, consisting (mainly) of a four digit exchange code plus a four digit number. The national significant number consists of a single digit area code followed by the local eight digit number – a total of nine digits. Within Australia, to access the number of a landline telephone in an area other than that in which the caller is located (including callers using mobile phones), it is first necessary to dial the Australian trunk code of 0 plus the area code, followed by the local number. Thus, the full national nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Telephone Numbering Plan
The French telephone numbering plan is used in Metropolitan France, French overseas departments and some overseas collectivities. France uses a ten-digit closed numbering plan, where the first two digits denote a geographic area, mobile or non-geographic number. * 01 * 02 Northwest France * 03 Northeast France * 04 Southeast France * 05 Southwest France * 06 Mobile phone services * 07 Mobile phone services * 08 Special phone numbers: Freephone () and shared-cost services. * 09 Non-geographic number (used by Voice over IP services) All geographic numbers are dialed in the ten-digit format, even for local calls. The international access code is the International Telecommunication Union's recommended 00. When calling France from abroad, the leading zero should be omitted: for example, to call a number in Southwest France, one would dial +33 5 xx xx xx xx. French people usually state phone numbers as a sequence of five double-digit numbers, e.g., 0x xx xx xx xx (and not, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computability Theory
Computability theory, also known as recursion theory, is a branch of mathematical logic, computer science, and the theory of computation that originated in the 1930s with the study of computable functions and Turing degrees. The field has since expanded to include the study of generalized computability and definability. In these areas, computability theory overlaps with proof theory and effective descriptive set theory. Basic questions addressed by computability theory include: * What does it mean for a function on the natural numbers to be computable? * How can noncomputable functions be classified into a hierarchy based on their level of noncomputability? Although there is considerable overlap in terms of knowledge and methods, mathematical computability theorists study the theory of relative computability, reducibility notions, and degree structures; those in the computer science field focus on the theory of subrecursive hierarchies, formal methods, and formal languages. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zero-based Numbering
Zero-based numbering is a way of numbering in which the initial element of a sequence is assigned the index 0, rather than the index 1 as is typical in everyday ''non-mathematical'' or ''non-programming'' circumstances. Under zero-based numbering, the initial element is sometimes termed the ''zeroth'' element, rather than the ''first'' element; ''zeroth'' is a coined ordinal number corresponding to the number zero. In some cases, an object or value that does not (originally) belong to a given sequence, but which could be naturally placed before its initial element, may be termed the zeroth element. There is not wide agreement regarding the correctness of using zero as an ordinal (nor regarding the use of the term ''zeroth''), as it creates ambiguity for all subsequent elements of the sequence when lacking context. Numbering sequences starting at 0 is quite common in mathematics notation, in particular in combinatorics, though programming languages for mathematics usuall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
China Telephone Numbering Plan
Telephone numbers in China are organized according to the Chinese Telephone Code Plan. The numerical formats of landlines and mobile phones are different: landlines have area codes, whereas mobile phones do not. In major cities, landline numbers consist of a two-digit area code followed by an eight-digit inner number. In other places, landline numbers consist of a three-digit area code followed by a seven- or eight-digit internal number. The numbers of mobile phones consist of eleven digits. When one landline is used to dial another landline within the same area, it is not necessary to specify the area code. The target number must be prepended between different regions with the trunk prefix, which is 0. Calling a mobile phone from a landline requires the addition of the "0" in front of the mobile phone number if they are not in the same area. Mobile to landline calls requires the "0" and the area code if the landline is not within the same place. Mobile to mobile calls does not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Country Calling Code
Country calling codes or country dial-in codes are telephone number prefixes for reaching telephone subscribers in the networks of the member countries or regions of the International Telecommunication Union (ITU). The codes are defined by the ITU-T in standards E.123 and E.164. The prefixes enable international direct dialing (IDD) and are also referred to as ''international subscriber dialing'' (ISD) codes. Country codes are a component of the international telephone numbering plan and are necessary only when dialing a telephone number to establish a call to another country. Country codes are dialed before the national telephone number. By convention, international telephone numbers are represented by prefixing the country code with a plus sign (+), which also indicates to the subscriber that the local international call prefix must first be dialed. For example, the international call prefix in all countries of the North American Numbering Plan is 011, while it is 00 in most E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Commission Number
The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. As a system of enzyme nomenclature, every EC number is associated with a recommended name for the corresponding enzyme-catalyzed reaction. EC numbers do not specify enzymes but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same EC number. Furthermore, through convergent evolution, completely different protein folds can catalyze an identical reaction (these are sometimes called non-homologous isofunctional enzymes) and therefore would be assigned the same EC number. By contrast, UniProt identifiers uniquely specify a protein by its amino acid sequence. Format of number Every enzyme code consists of the letters "EC" followed by four numbers separated by periods. Those numbers represent a progressively finer classification of the enzyme. Preliminary EC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argentine Telephone Numbering Plan
In Argentina, area codes are two, three, or four digits long (after the initial zero). Local customer numbers are six to eight figures long. The total number of digits is ten, for example, phone number (11) 1234-5678 for Buenos Aires is made up of a 2-digit area code number and an 8-digit subscriber's number, while (383) 123-4567 would be an example of a Catamarca number. Local dialing Local landline phone numbers in Argentina can have 6, 7 or 8 digits, depending on where they are located: * Most of Greater Buenos Aires uses 8 digits * Second-tier cities use 7 digits * Remaining towns and cities use 6 digits Local numbers usually begin with a 4, although in recent times numbers having 2, 3, 5, 6, or even 7 as the first digit are not uncommon. Thus, for example to call a local number within Buenos Aires, one should dial 1234–5678; within Mar del Plata, 123-4567 and within Villa Carlos Paz, 12–3456. For mobile phone dialing, see the corresponding section below. Recent c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E Number
E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly found on food labels, their safety assessment and approval are the responsibility of the European Food Safety Authority (EFSA). The fact that an additive has an E number implies that its use was at one time permitted in products for sale in the European Single Market; some of these additives are no longer allowed today. Having a single unified list for food additives was first agreed upon in 1962 with food colouring. In 1964, the directives for preservatives were added, in 1970 antioxidants were added, in 1974 emulsifiers, stabilisers, thickeners and gelling agents were added as well. Numbering schemes The numbering scheme follows that of the International Numbering System (INS) as determined by the '' Codex Alimentarius'' committee, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
