论文标题
置换不变的停车场
Permutation Invariant Parking Assortments
论文作者
论文摘要
我们介绍停车场分类,泛化停车功能,具有各种长度的汽车。在这种情况下,有$ n \ in \ mathbb {n} $长度为$ \ mathbf {y} =(y_1,y_2,y_2,\ ldots,y_n)\ in \ mathbb {n}^n $输入一条单向街道,带有$ m = \ sum_ = \ sum_ = \ sum_ = 1 = 1}^ny $ $汽车有停车偏好$ \ mathbf {x} =(x_1,x_2,\ ldots,x_n)\在[m]^n $中,其中$ [m]:= \ {1,2,\ ldots,m \ \} $,并在街上进入街道。每个汽车$ i \ in [n] $,带长度$ y_i $和偏好$ x_i $,遵循经典停车规则的自然扩展:它开始在其首选$ x_i $和公园中寻找停车位,并在此后的第一个$ y_i $ contigiully可用的位置上寻找停车位。如果所有汽车都能在优先列表下停放$ \ mathbf {x} $,我们说$ \ mathbf {x} $是$ \ mathbf {y} $的停车场。埃伦博格(Ehrenborg)和哈普(Happ)引入的停车场也概括了停车序列,因为每辆汽车都寻求在过去的偏爱中找到的第一个连续点。给定一个停车场$ \ Mathbf {X} $对于$ \ Mathbf {y} $,我们说如果$ \ Mathbf {X} $的所有重新安排也是$ \ Mathbf {y} $的停车产品,则是置换不变的。尽管所有停车功能都是置换式不变的,但总体上的停车场并非如此,激发了该物业表征的需求。尽管在\ mathbb {n} $和$ \ mathbf {y} \ in \ mathbb {n}^n $中获得了任意$ n \ in \ mathbb {n} $中的完整表征,但我们仍然难以捉摸,但我们这样做是$ n = 2,3 $。鉴于这些结果的技术性,我们介绍了最小不变的汽车长度的概念,为此,唯一不变的停车位是所有首选项列表。我们为任何$ n \ in \ Mathbb {n} $中的任何$ n \提供了简洁的,基于甲骨文的表征。我们的结果围绕最小的汽车长度也适用于停车序列。
We introduce parking assortments, a generalization of parking functions with cars of assorted lengths. In this setting, there are $n\in\mathbb{N}$ cars of lengths $\mathbf{y}=(y_1,y_2,\ldots,y_n)\in\mathbb{N}^n$ entering a one-way street with $m=\sum_{i=1}^ny_i$ parking spots. The cars have parking preferences $\mathbf{x}=(x_1,x_2,\ldots,x_n)\in[m]^n$, where $[m]:=\{1,2,\ldots,m\}$, and enter the street in order. Each car $i \in [n]$, with length $y_i$ and preference $x_i$, follows a natural extension of the classical parking rule: it begins looking for parking at its preferred spot $x_i$ and parks in the first $y_i$ contiguously available spots thereafter, if there are any. If all cars are able to park under the preference list $\mathbf{x}$, we say $\mathbf{x}$ is a parking assortment for $\mathbf{y}$. Parking assortments also generalize parking sequences, introduced by Ehrenborg and Happ, since each car seeks for the first contiguously available spots it fits in past its preference. Given a parking assortment $\mathbf{x}$ for $\mathbf{y}$, we say it is permutation invariant if all rearrangements of $\mathbf{x}$ are also parking assortments for $\mathbf{y}$. While all parking functions are permutation invariant, this is not the case for parking assortments in general, motivating the need for characterization of this property. Although obtaining a full characterization for arbitrary $n\in\mathbb{N}$ and $\mathbf{y}\in\mathbb{N}^n$ remains elusive, we do so for $n=2,3$. Given the technicality of these results, we introduce the notion of minimally invariant car lengths, for which the only invariant parking assortment is the all ones preference list. We provide a concise, oracle-based characterization of minimally invariant car lengths for any $n\in\mathbb{N}$. Our results around minimally invariant car lengths also hold for parking sequences.