Improving the Predicting Power of Partial Order Based QSARs through Linear Extensions

2002 ◽  
Vol 42 (4) ◽  
pp. 806-811 ◽  
Author(s):  
Lars Carlsen ◽  
Dorte B. Lerche ◽  
Peter B. Sørensen
Chemosphere ◽  
2004 ◽  
Vol 55 (7) ◽  
pp. 1005-1025 ◽  
Author(s):  
Dorte Lerche ◽  
Sanae Y. Matsuzaki ◽  
Peter B. Sørensen ◽  
Lars Carlsen ◽  
Ole John Nielsen

Chemosphere ◽  
2002 ◽  
Vol 49 (6) ◽  
pp. 637-649 ◽  
Author(s):  
Dorte Lerche ◽  
Peter B. Sørensen ◽  
Henrik Sørensen Larsen ◽  
Lars Carlsen ◽  
Ole John Nielsen

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Benjamin Iriarte

International audience Given an underlying undirected simple graph, we consider the set of all acyclic orientations of its edges. Each of these orientations induces a partial order on the vertices of our graph, and therefore we can count the number of linear extensions of these posets. We want to know which choice of orientation maximizes the number of linear extensions of the corresponding poset, and this problem is solved essentially for comparability graphs and odd cycles, presenting several proofs. We then provide an inequality for general graphs and discuss further techniques.


2016 ◽  
Vol 8 (1) ◽  
pp. 134-149
Author(s):  
K. Nageswara Rao ◽  
K.A. Germina ◽  
P. Shaini

A distance compatible set labeling (dcsl) of a connected graph $G$ is an injective set assignment $f : V(G) \rightarrow 2^{X},$ $X$ being a nonempty ground set, such that the corresponding induced function $f^{\oplus} :E(G) \rightarrow 2^{X}\setminus \{\emptyset\}$ given by $f^{\oplus}(uv)= f(u)\oplus f(v)$ satisfies $\mid f^{\oplus}(uv) \mid = k_{(u,v)}^{f}d_{G}(u,v) $ for every pair of distinct vertices $u, v \in V(G),$ where $d_{G}(u,v)$ denotes the path distance between $u$ and $v$ and $k_{(u,v)}^{f}$ is a constant, not necessarily an integer. A dcsl $f$ of $G$ is $k$-uniform if all the constant of proportionality with respect to $f$ are equal to $k,$ and if $G$ admits such a dcsl then $G$ is called a $k$-uniform dcsl graph. The $k$-uniform dcsl index of a graph $G,$ denoted by $\delta_{k}(G)$ is the minimum of the cardinalities of $X,$ as $X$ varies over all $k$-uniform dcsl-sets of $G.$ A linear extension ${\mathbf{L}}$ of a partial order ${\mathbf{P}} = (P, \preceq)$ is a linear order on the elements of $P$, such that $ x \preceq y$ in ${\mathbf{P}}$ implies $ x \preceq y$ in ${\mathbf{L}}$, for all $x, y \in P$. The dimension of a poset ${\mathbf{P}},$ denoted by $dim({\mathbf{P}}),$ is the minimum number of linear extensions on ${\mathbf{P}}$ whose intersection is `$\preceq$'. In this paper we prove that $dim({\mathcal{F}}) \leq \delta_{k}(P^{+k}_n),$ where ${\mathcal{F}}$ is the range of a $k$-uniform dcsl of the $k$-uniform caterpillar, denoted by $P^{+k}_n \ (n\geq 1, k\geq 1)$ on `$n(k+1)$' vertices.


1996 ◽  
Vol 73 (2) ◽  
pp. 193-206 ◽  
Author(s):  
Graham Brightwell ◽  
Hans Jürgen Prömel ◽  
Angelika Steger

1994 ◽  
Vol 4 (1) ◽  
pp. 108-123 ◽  
Author(s):  
Noga Alon ◽  
Bela Bollobas ◽  
Graham Brightwell ◽  
Svante Janson

Author(s):  
Topi Talvitie ◽  
Kustaa Kangas ◽  
Teppo Niinimäki ◽  
Mikko Koivisto

Counting the linear extensions of a given partial order not only has several applications in artificial intelligence but also represents a hard problem that challenges modern paradigms for approximate counting. Recently, Talvitie et al. (AAAI 2018) showed that an exponential time scheme beats the fastest known polynomial time schemes in practice, even if allowing hours of running time. Here, we present a novel scheme, relaxation Tootsie Pop, which in our experiments exhibits polynomial characteristics and significantly outperforms previous schemes. We also instantiate state-of-the-art model counters for CNF formulas; two natural encodings yield schemes that, however, are inferior to the more specialized schemes.


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