Journal of Combinatorial Theory Series B ( IF 1.4 ) Pub Date : 2020-03-20 , DOI: 10.1016/j.jctb.2020.03.004 Michal Karoński , Ed Overman , Boris Pittel
Existence of a perfect matching in a random bipartite digraph with bipartition , , is studied. The graph is generated in two rounds of random selections of a potential matching partner such that the average number of selections made by each vertex overall is below 2. More precisely, in the first round each vertex chooses a potential mate uniformly at random, and independently of all vertices. Given a fixed integer m, a vertex is classified as unpopular if it has been chosen by at most m vertices from the other side. Each unpopular vertex makes yet another uniform/independent selection of a potential mate. The expected number of selections made by a generic vertex v, i.e. its out-degree, is asymptotic to . Aided by Matlab software, we prove that for , whence for all , the resulting bipartite graph has a perfect matching a.a.s. (asymptotically almost surely). On the other hand, for a.a.s. a perfect matching does not exist. For the non-bipartite version of this model with vertex set we show that already for a.a.s. there exists a partial matching which leaves unmatched a fraction of vertices.
中文翻译:
随机图上的平均匹配度低于2的完美匹配
具有二等分的随机二部有向图的完美匹配的存在 , ,正在研究中。该图是在两轮潜在匹配对象的随机选择中生成的,因此每个顶点总体选择的平均数目低于2。更准确地说,在第一轮中,每个顶点均会随机且独立地均匀选择一个潜在伴侣。所有顶点。给定一个固定的整数m,如果一个顶点最多被另一侧的m个顶点选中,则将其分类为不受欢迎。每个不受欢迎的顶点都会对潜在配偶进行另一个统一/独立的选择。通用顶点v的预期选择次数(即其出学位程度)渐近于。在Matlab软件的帮助下,我们证明了,所有人 ,生成的二部图具有完美的匹配aas(渐近几乎确定地)。另一方面,对于aas不存在完美匹配。对于具有顶点集的该模型的非双向版本 我们已经证明了 aas存在部分匹配项,从而留下了不匹配的a 顶点的分数。