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Comparability graph: различия между версиями

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'''Comparability graph''' --- граф сравнимости.  
'''Comparability graph''' — ''[[граф сравнимости]].''


Let <math>G = (V,E)</math> be an undirected graph and let <math>F</math> be an
Let <math>\,G = (V,E)</math> be an [[undirected graph]] and let <math>\,F</math> be an ''orientation'' of its [[edge|edges]] (i.e. <math>\,(V,F)</math> is the resulting [[oriented graph]]).
''orientation'' of its edges (i.e. <math>(V,F)</math> is the resulting oriented graph).
<math>\,F</math> is called a '''[[transitive orientation]]''' of <math>\,G</math> if the following
<math>F</math> is called a '''transitive orientation''' of <math>G</math> if the following
properties hold:
properties hold:


<math>F \cap F^{-1} = \emptyset\mbox{ and }F + F^{-1} = E\mbox{ and }F^{2} \subseteq F,</math>
<math>\,F \cap F^{-1} = \emptyset\mbox{ and }F + F^{-1} = E\mbox{ and }F^{2} \subseteq F,</math>


where <math>F^{2} = \{(a,c)| \; \exists_{b \in V}(a,b) \in F \wedge (b,c)
where <math>\,F^{2} = \{(a,c)| \; \exists_{b \in V}(a,b) \in F \wedge (b,c) \in F\}</math>.
\in F\}</math>.


A graph <math>G</math> which admits a '''transitive orientation''' of its edges is called
A [[graph, undirected graph, nonoriented graph|graph]] <math>\,G</math> which admits a '''transitive orientation''' of its edges is called a '''comparability graph'''.
a '''comparability graph'''.


If graph <math>G</math> is a '''comparability''' graph, then this also holds for every induced
If graph <math>\,G</math> is a '''comparability''' graph, then this also holds for every [[induced
subgraph of <math>G</math>.
subgraph]] of <math>\,G</math>.


The other name is a '''Transitively orientable graph'''.
The other name is a '''[[Transitively orientable graph]]'''.
 
==Литература==
 
* Евстигнеев В.А., Касьянов В.Н. Словарь по графам в информатике. — Новосибирск: Сибирское Научное Издательство, 2009.