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Alternation (geometry), Alternation
Alternation or AlterNation may refer to: * Alternation (complexity), a resource in computational complexity theory * Alternation (formal language theory), the set union of two sets of strings in formal language theory and pattern matching * Alternation (geometry), a geometric operation for deriving polytopes from other polytopes * Alternation (linguistics), a variation in the phonological form of a morpheme * Diathesis alternation, a linguistics term relating to verb use * R/N alternation; see Rhotacism (sound change) * Logical disjunction In logic, disjunction (also known as logical disjunction, logical or, logical addition, or inclusive disjunction) is a logical connective typically notated as \lor and read aloud as "or". For instance, the English language sentence "it is ..., the ''or'' function * ''AlterNation'', a show on NE1 FM * WSTB, a radio station in Streetsboro, Ohio known as ''The AlterNation'' {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternation (complexity)
In computational complexity theory, an alternating Turing machine (ATM) is a non-deterministic Turing machine (NTM) with a rule for accepting computations that generalizes the rules used in the definition of the complexity classes NP (complexity), NP and co-NP. The concept of an ATM was set forth by Ashok K. Chandra, Chandra and Larry Stockmeyer, Stockmeyer and independently by Dexter Kozen, Kozen in 1976, with a joint journal publication in 1981. Definitions Informal description The definition of NP uses the ''existential mode'' of computation: if ''any'' choice leads to an accepting state, then the whole computation accepts. The definition of co-NP uses the ''universal mode'' of computation: only if ''all'' choices lead to an accepting state does the whole computation accept. An alternating Turing machine (or to be more precise, the definition of acceptance for such a machine) alternates between these modes. An alternating Turing machine is a non-deterministic Turing ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternation (formal Language Theory)
In formal language theory and pattern matching, alternation is the union of two sets of strings, or equivalently the logical disjunction of two patterns describing sets of strings. Regular languages are closed under alternation, meaning that the alternation of two regular languages is again regular. In implementations of regular expressions, alternation is often expressed with a vertical bar connecting the expressions for the two languages whose union is to be matched, while in more theoretical studies the plus sign may instead be used for this purpose. The ability to construct finite automata for unions of two regular languages that are themselves defined by finite automata is central to the equivalence between regular languages defined by automata and by regular expressions. Other classes of languages that are closed under alternation include context-free languages and recursive languages. The vertical bar notation for alternation is used in the SNOBOL language and some other la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |