翻訳と辞書 Words near each other ・ Backhouse (surname) ・ Backhouse baronets ・ Backhouse's Bank ・ Backhouse's constant ・ Backhousia ・ Backhousia citriodora ・ Backhousia leptopetala ・ Backhousia myrtifolia ・ Backhousia sciadophora ・ Backhousia subargentea ・ Backhousia tetraptera ・ Backing Australia's Ability ・ Backing musicians for Trey Anastasio ・ Backing track ・ Backing vocalist ・ Backjumping ・ Backlash ・ Backlash (1947 film) ・ Backlash (1956 film) ・ Backlash (1986 film) ・ Backlash (2000) ・ Backlash (2001) ・ Backlash (2002) ・ Backlash (2003) ・ Backlash (2004) ・ Backlash (2005) ・ Backlash (2006) ・ Backlash (2007) ・ Backlash (2008) ・ Backlash (2009) Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Backjumping ： ウィキペディア英語版 Backjumping In backtracking algorithms, backjumping is a technique that reduces search space, therefore increasing efficiency. While backtracking always goes up one level in the search tree when all values for a variable have been tested, backjumping may go up more levels. In this article, a fixed order of evaluation of variables $x\_1,\backslash ldots,x\_n$ is used, but the same considerations apply to a dynamic order of evaluation. Image:Backtracking-no-backjumping.svg|A search tree visited by regular backtracking Image:Backtracking-with-backjumping.svg|A backjump: the grey node is not visited ==Definition== Whenever backtracking has tried all values for a variable without finding any solution, it reconsiders the last of the previously assigned variables, changing its value or further backtracking if no other values are to be tried. If $x\_1=a\_1,\backslash ldots,x\_k=a\_k$ is the current partial assignment and all values for $x\_$ have been tried without finding a solution, backtracking concludes that no solution extending $x\_1=a\_1,\backslash ldots,x\_k=a\_k$ exists. It then "goes up" to $x\_k$, changing its value if possible, backtracking again otherwise. The partial assignment is not always necessary in full to prove that no value of $x\_$ lead to a solution. In particular, a prefix of the partial assignment may have the same property, that is, there exists an index The efficiency of a backjumping algorithm depends on how high it is able to backjump. Ideally, the algorithm could jump from $x\_$ to whichever variable $x\_j$ is such that the current assignment to $x\_1,\backslash ldots,x\_j$ cannot be extended to form a solution with any value of $x\_$. If this is the case, $j$ is called a ''safe jump''. Establishing whether a jump is safe is not always feasible, as safe jumps are defined in terms of the set of solutions, which is what the algorithm is trying to find. In practice, backjumping algorithms use the lowest index they can efficiently prove to be a safe jump. Different algorithms use different methods for determining whether a jump is safe. These methods have different cost, but a higher cost of finding a higher safe jump may be traded off a reduced amount of search due to skipping parts of the search tree. 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「Backjumping」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.