اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe cycle structure of compositions of random involutions
88
0
0.0
(
0
)
تأليف
Michael Lugo
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
In this article we consider the cycle structure of compositions of pairs of involutions in the symmetric group S_n chosen uniformly at random. These can be modeled as modified 2-regular graphs, giving rise to exponential generating functions. A composition of two random involutions in S_n typically has about n^(1/2) cycles, and the cycles are characteristically of length n^(1/2). Compositions of two random fixed-point-free involutions, on the other hand, typically have about log n cycles and are closely related to permutations with all cycle lengths even. The number of factorizations of a random permutation into two involutions appears to be asymptotically lognormally distributed, which we prove for a closely related probabilistic model. This study is motivated by the observation that the number of involutions in [n] is (n!)^(1/2) times a subexponential factor; more generally the number of permutations with all cycle lengths in a finite set S is n!^(1-1/m) times a subexponential factor, and the typical number of k-cycles is nearly n^(k/m)/k. Connections to pattern avoidance in involutions are also considered.
قيم البحث
اقرأ أيضاً
We use moment method to understand the cycle structure of the composition of independent invariant permutations. We prove that under a good control on fixed points and cycles of length 2, the limiting joint distribution of the number of small cycles
is the same as in the uniform case i.e. for any positive integer k, the number of cycles of length k converges to the Poisson distribution with parameter 1/k and is asymptotically independent of the number of cycles of length k different from k.
The group of almost Riordan arrays contains the group of Riordan arrays as a subgroup. In this note, we exhibit examples of pseudo-involutions, involutions and quasi-involutions in the group of almost Riordan arrays.
The random reversal graph offers new perspectives, allowing to study the connectivity of genomes as well as their most likely distance as a function of the reversal rate. Our main result shows that the structure of the random reversal graph changes d
ramatically at $lambda_n=1/binom{n+1}{2}$. For $lambda_n=(1-epsilon)/binom{n+1}{2}$, the random graph consists of components of size at most $O(nln(n))$ a.s. and for $(1+epsilon)/binom{n+1}{2}$, there emerges a unique largest component of size $sim wp(epsilon) cdot 2^ncdot n$!$ a.s.. This giant component is furthermore dense in the reversal graph.
Write $mathcal{C}(G)$ for the cycle space of a graph $G$, $mathcal{C}_kappa(G)$ for the subspace of $mathcal{C}(G)$ spanned by the copies of the $kappa$-cycle $C_kappa$ in $G$, $mathcal{T}_kappa$ for the class of graphs satisfying $mathcal{C}_kappa(G
)=mathcal{C}(G)$, and $mathcal{Q}_kappa$ for the class of graphs each of whose edges lies in a $C_kappa$. We prove that for every odd $kappa geq 3$ and $G=G_{n,p}$, [max_p , Pr(G in mathcal{Q}_kappa setminus mathcal{T}_kappa) rightarrow 0;] so the $C_kappa$s of a random graph span its cycle space as soon as they cover its edges. For $kappa=3$ this was shown by DeMarco, Hamm and Kahn (2013).
Given a hereditary property of graphs $mathcal{H}$ and a $pin [0,1]$, the edit distance function ${rm ed}_{mathcal{H}}(p)$ is asymptotically the maximum proportion of edge-additions plus edge-deletions applied to a graph of edge density $p$ sufficien
t to ensure that the resulting graph satisfies $mathcal{H}$. The edit distance function is directly related to other well-studied quantities such as the speed function for $mathcal{H}$ and the $mathcal{H}$-chromatic number of a random graph. Let $mathcal{H}$ be the property of forbidding an ErdH{o}s-R{e}nyi random graph $Fsim mathbb{G}(n_0,p_0)$, and let $varphi$ represent the golden ratio. In this paper, we show that if $p_0in [1-1/varphi,1/varphi]$, then a.a.s. as $n_0toinfty$, begin{align*} {rm ed}_{mathcal{H}}(p) = (1+o(1)),frac{2log n_0}{n_0} cdotminleft{ frac{p}{-log(1-p_0)}, frac{1-p}{-log p_0} right}. end{align*} Moreover, this holds for $pin [1/3,2/3]$ for any $p_0in (0,1)$.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
