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In mathematics, Hensel's lemma, also known as Hensel's lifting lemma, named after Kurt Hensel, is a result in modular arithmetic, stating that if a polynomial equation has a simple root modulo a prime number , then this root corresponds to a unique root of the same equation modulo any higher power of , which can be found by iteratively "lifting" the solution modulo successive powers of . More generally it is used as a generic name for analogues for complete commutative rings (including ''p''-adic fields in particular) of the Newton method for solving equations. Since ''p''-adic analysis is in some ways simpler than real analysis, there are relatively neat criteria guaranteeing a root of a polynomial. == Statement == Let be a polynomial with integer (or ''p''-adic integer) coefficients, and let ''m'',''k'' be positive integers such that ''m'' ≤ ''k''. If ''r'' is an integer such that : and then there exists an integer ''s'' such that : Furthermore, this ''s'' is unique modulo ''p''''k''+m, and can be computed explicitly as : where In this formula for ''t'', the division by ''p''''k'' denotes ordinary integer division (where the remainder will be 0), while negation, multiplication, and multiplicative inversion are performed in . As an aside, if , then 0, 1, or several ''s'' may exist (see Hensel Lifting below). 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Hensel's lemma」の詳細全文を読む スポンサード リンク
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