📄 dual.html
字号:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD W3 HTML 2.0//EN">
<HTML lang="en-US">
<HEAD>
<TITLE>dual</TITLE>
<META name="description"
content="Definition of dual,
possibly with links to more information and implementations.">
<META name="keywords" content="dual">
</HEAD>
<BODY BGCOLOR="#FFFFFF">
<H1>dual</H1>
<P>
(definition)
<P>
<strong>Definition:</strong>
The dual of a <a href="planargraph.html" tppabs="http://hissa.nist.gov/dads/HTML/planargraph.html"><em>planar graph</em></a>, G, is a <a href="graph.html" tppabs="http://hissa.nist.gov/dads/HTML/graph.html"><em>graph</em></a> with a <a href="vertex.html" tppabs="http://hissa.nist.gov/dads/HTML/vertex.html"><em>vertex</em></a> for each region in G and an <a href="edge.html" tppabs="http://hissa.nist.gov/dads/HTML/edge.html"><em>edge</em></a> between vertices for each pair of adjacent regions. The new edge crosses the edge in G which is the boundary between the adjacent regions.
<P><em>Note:
<IMG src="dual.gif" tppabs="http://hissa.nist.gov/dads/HTML/Images/dual.gif" height=266 width=303 align=right> The dual of a planar graph is also planar. The original graph is the dual of the dual. That is, they are duals of each other. <P> In the accompanying figure, the black circles and solid lines are one planar graph. The white squares and dotted lines are another planar graph. Each is the dual of the other.</em>
<P>Author: <a href="terms.html#authorPEB" tppabs="http://hissa.nist.gov/dads/terms.html#authorPEB">PEB</a>
<H2>More information</H2>
The <A HREF="javascript:if(confirm('http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://csr.csc.uvic.ca/%7Ecos/venn/VennGraphEJC.html \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://csr.csc.uvic.ca/%7Ecos/venn/VennGraphEJC.html'" tppabs="http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://csr.csc.uvic.ca/%7Ecos/venn/VennGraphEJC.html">dual of a Venn diagram</A>, also <A HREF="javascript:if(confirm('http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wisdom.weizmann.ac.il/Journal/Surveys/ds5/VennGraphEJC.html \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wisdom.weizmann.ac.il/Journal/Surveys/ds5/VennGraphEJC.html'" tppabs="http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wisdom.weizmann.ac.il/Journal/Surveys/ds5/VennGraphEJC.html">here</A>. <A HREF="javascript:if(confirm('http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wpi.edu/%7Ehservat/self1.html \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wpi.edu/%7Ehservat/self1.html'" tppabs="http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.wpi.edu/%7Ehservat/self1.html">Self-dual maps</A>, that is, planar graphs which are duals of themselves.
<hr>
Go to the
<A HREF="terms.html" tppabs="http://hissa.nist.gov/dads/terms.html">Algorithms, Data Structures, and Problems</A>
home page.
<hr>
If you have suggestions, corrections, or comments, please get in touch
with
<a href="javascript:if(confirm('http://hissa.nist.gov/~black/black.html \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://hissa.nist.gov/~black/black.html'" tppabs="http://hissa.nist.gov/~black/black.html">Paul E. Black</a>
(<a href="mailto:paul.black@nist.gov">paul.black@nist.gov</a>).
<p>
Entry modified Wed Sep 29 13:27:40 1999.<BR>
HTML page formatted Wed Dec 22 09:35:12 1999.
<P>
This page's URL is
<A href="dual.html" tppabs="http://hissa.nist.gov/dads/HTML/dual.html">http://hissa.nist.gov/dads/HTML/dual.html</A>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -