翻訳と辞書
Words near each other
・ Major Harris
・ Major Harris (singer)
・ Major Hart River
・ Major Havoc
・ Major Henderson incident
・ Major histocompatibility complex
・ Major histocompatibility complex and sexual selection
・ Major histocompatibility complex, class I-related
・ Major histocompatibility complex, class II, DP alpha 1
・ Major histocompatibility complex, class II, DQ alpha 1
・ Major Historical and Cultural Site Protected at the National Level
・ Major historical and cultural sites protected by Shandong Province
・ Major Hockey League
・ Major Holley
・ Major Hoople's Boarding House
Major index
・ Major Indoor Soccer League
・ Major Indoor Soccer League (1978–92)
・ Major Indoor Soccer League (2001–08)
・ Major Indoor Soccer League (2008–14)
・ Major Information Technology Companies of the World
・ Major Intermediate A Hockey League
・ Major intrinsic proteins
・ Major Isidoro
・ Major Israel McCreight
・ Major Jackson
・ Major Jacob Hasbrouck Jr. House
・ Major James Coldwell
・ Major Jarrett
・ Major John André Monument


Dictionary Lists
翻訳と辞書 辞書検索 [ 開発暫定版 ]
スポンサード リンク

Major index : ウィキペディア英語版
Major index
In mathematics (and particularly in combinatorics), the major index of a permutation is the sum of the positions of the descents of the permutation. In symbols, the major index of the permutation ''w'' is
:
\operatorname(w) = \sum_ i.

For example, if ''w'' is given in one-line notation by ''w'' = 351624 (that is, ''w'' is the permutation of such that ''w''(1) = 3, ''w''(2) = 5, etc.) then ''w'' has descents at positions 2 (from 5 to 1) and 4 (from 6 to 2) and so maj(''w'') = 2 + 4 = 6.
This statistic is named after Major Percy Alexander MacMahon who showed in 1913 that the distribution of the major index on all permutations of a fixed length is the same as the distribution of inversions. That is, the number of permutations of length ''n'' with ''k'' inversions is the same as the number of permutations of length ''n'' with major index equal to ''k''. (These numbers are known as ''Mahonian numbers'', also in honor of MacMahon.〔M. Bóna, Combinatorics of Permutations, 2004, p. 43ff, ISBN 1-58488-434-7.〕) In fact, a stronger result is true: the number of permutations of length ''n'' with major index ''k'' and ''i'' inversions is the same as the number of permutations of length ''n'' with major index ''i'' and ''k'' inversions, that is, the two statistics are equidistributed. For example, the number of permutations of length 4 with given major index and number of inversions is given in the table below.
:\begin
& 0&1&2&3&4&5&6 \\
\hline
0&1&0&0&0&0&0&0 \\
1&0&1&1&1&0&0&0 \\
2&0&1&2&1&1&0&0 \\
3&0&1&1&2&1&1&0 \\
4&0&0&1&1&2&1&0 \\
5&0&0&0&1&1&1&0 \\
6&0&0&0&0&0&0&1
\end

== References ==

*.

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「Major index」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.