Talk:Alternating permutation

Zigzag & alternating meaning

There seems to be some variation in the sources as to the definitions. For example Mathworld does not require c₁< c₂ for alternating permutation but Sloane does. I've tried to create the most reasonable compromise in which A_n is the number of alternating permutations and Z_n is the number of zigzag permutations, where A_n and Z_n are as used in Mathworld.--RDBury (talk) 15:06, 18 January 2009 (UTC)[reply]

Notation / Minor errors

Why is the number of alternating permutations denoted by A_n in Section 1 and by E_n in section 2? Also in the proof of André's Thm, "The number of ways to choose a permutation of {1,...,n+1} that is either alternating or reverse-alternating is E_(n+1)" should be 2 E_(n+1), right? In the second step of the combinatorial proof of the identity, "choose a reverse-alternating permutation ... of the set {1,...,k}" should rather refer to the subset of size k chosen in the first step (this is not necessarily {1,...k}). Similarly, the set in the third step should be the complement of the chosen subset. Right? -- Martin B. --85.181.225.53 (talk) 09:42, 11 July 2015 (UTC)[reply]

Assessment comment

The comment(s) below were originally left at Talk:Alternating permutation/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Geometry guy 00:32, 22 May 2007 (UTC) What 'c₁< c₂' means? —Preceding unsigned comment added by 130.231.62.1 (talk) 12:58, 7 May 2008 (UTC)[reply]

Last edited at 12:59, 7 May 2008 (UTC). Substituted at 01:45, 5 May 2016 (UTC)