On Group bijections $ϕ$ with $ϕ(B)=A$ and $\forall a\in B, aϕ(a) \notin A$

dc.creatorHamidoune, Yahya Ould
dc.date2008-12-13
dc.date.accessioned2026-07-07T12:12:40Z
dc.date.available2026-07-07T12:12:40Z
dc.descriptionA {\em Wakeford pairing} from $S$ onto $T$ is a bijection $ϕ: S \to T$ such that $xϕ(x)\notin T,$ for every $x\in S.$ The number of such pairings will be denoted by $μ(S,T)$. Let $A$ and $ B$ be finite subsets of a group $G$ with $1\notin B$ and $|A|=|B|.$ Also assume that the order of every element of $B$ is $\ge |B|$. Extending results due to Losonczy and Eliahou-Lecouvey, we show that $μ(B,A)\neq 0.$ Moreover we show that $μ(B,A)\ge \min \{\frac{||B|+1}{3},\frac{|B|(q-|B|-1)}{2q-|B|-4}\},$ unless there is $a\in A$ such that $|Aa^{-1}\cap B|=|B|-1$ or $Aa^{-1}$ is a progression. In particular, either $μ(B,B) \ge \min \{\frac{||B|+1}{3},\frac{|B|(q-|B|-1)}{2q-|B|-4}\},$ or for some $a\in B,$ $Ba^{-1}$ is a progression.
dc.identifierhttps://arxiv.org/abs/0812.2522
dc.identifierhttp://arxiv.org/abs/0812.2522
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/210618
dc.subjectCombinatorics
dc.subject20D60, 11B60, 11B34
dc.titleOn Group bijections $ϕ$ with $ϕ(B)=A$ and $\forall a\in B, aϕ(a) \notin A$
dc.typetext

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