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This article is cited in 3 scientific papers (total in 3 papers)
Discrete mathematics and mathematical cybernetics
On enumeration of posets defined on finite set
V. I. Rodionov Udmurt State University, ul. Universitetskaya, 1, 426034, Izhevsk, Russia
Abstract:
If $T_0(n)$ is the number of partial orders (labeled $T_0$-topologies) defined on a finite set of $n$ elements then the formula hold $$ T_0(n)=\sum\limits_{p_1+\ldots+p_k=n} (-1)^{n-k}\,\frac{n!}{p_1!\ldots p_k!}\,W(p_1,\ldots,p_k), $$ where the summation is over all ordered sets $(p_1,\ldots,p_k)$ of positive integers such that $p_1+\ldots+p_k=n$. The number $W(p_1,\ldots,p_k)$ is the number of partial orders of a special form. If $D_k$ is the dihedral group of order $2k$ then $W(p_{\pi(1)},\ldots,p_{\pi(k)})=W(p_1,\ldots,p_k)$ for all $\pi\in D_k$. We studied the complemented partial orders.
Keywords:
graph enumeration, poset, finite topology.
Received April 15, 2016, published May 10, 2016
Citation:
V. I. Rodionov, “On enumeration of posets defined on finite set”, Sib. Èlektron. Mat. Izv., 13 (2016), 318–330
Linking options:
https://www.mathnet.ru/eng/semr675 https://www.mathnet.ru/eng/semr/v13/p318
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