📄 content-4-2-1.htm
字号:
<html>
<head>
<title>guanxidehecheng</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<style type="text/css">
<!--
.unnamed2 { font-size: 10pt; font-weight: bold}
.unnamed1 { font-size: 9pt; font-weight: normal}
-->
</style>
</head>
<body bgcolor="#FFFFFF" background="IMAGE/di.gif">
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td>
<p style="line-height: 150%" align="center"><b><font size="5">关系的合成</font></b> </p>
<p style="line-height: 150%" align="left" ><b>定义1 ：关系的合成</b> </p>
<p style="line-height: 150%" align="left" > 设 R 是从集合
X 到集合 Y 的<a href="content-4-1-1.htm#content-4-1-1-guanxi">关系</a>，并且 S
是从集合 Y 到集合 Z 的关系。于是，可把从 X 到 Z 的关系R<img src="image/juhao.GIF" width="8" height="13">S
定义成 </p>
<p style="line-height: 150%" align="center" > R<img src="image/juhao.GIF" width="8" height="13">S={<x,z>|(x<img src="image/shuyu.gif" width="13" height="11">X)<img src="image/hequ.gif" width="9" height="11">(z<img src="image/shuyu.gif" width="13" height="11">Z)<img src="image/hequ.gif" width="9" height="11"><img src="image/cunzai.gif" width="7" height="11">y((y<img src="image/shuyu.gif" width="13" height="11">Y)<img src="image/hequ.gif" width="9" height="11">(<x,y><img src="image/shuyu.gif" width="13" height="11">R)<img src="image/hequ.gif" width="9" height="11">(<y,z><img src="image/shuyu.gif" width="13" height="11">S))} </p>
<p style="line-height: 150%" align="left" > 通常称 R<img border="0" src="Image/juhao.gif" width="8" height="13">S
是关系 R 和 S 的合成关系。从 R 和 S 求得 R<img src="image/juhao.GIF" width="8" height="13">S
的运算，称为关系的合成。 </p>
<p style="line-height: 150%" align="left" ><b>例:</b>设A={x<sub>1</sub>,x<sub>2</sub>,x<sub>3</sub>},B={y<sub>1</sub>,y<sub>2</sub>,y<sub>3</sub>},C={z<sub>1</sub>,z<sub>2</sub>,z<sub>3</sub>},<br>
A到B的关系R<sub>1</sub>={<x<sub>1</sub>,y<sub>1</sub>>,<x<sub>1</sub>,y<sub>2</sub>>,<x<sub>1</sub>,y<sub>3</sub>>,<x<sub>2</sub>,y<sub>2</sub>>}<br>
B到C的关系R<sub>2</sub>={<y<sub>1</sub>,z<sub>2</sub>>,<y<sub>2</sub>,z<sub>3</sub>>,<y<sub>3</sub>,z<sub>3</sub>>} </p>
<p style="line-height: 150%" align="left" >
则:从A到C的合成关系<br>
R=R<sub>1</sub><img border="0" src="Image/juhao.gif" width="8" height="13">R<sub>2</sub><br>
={<x<sub>1</sub>,z<sub>2</sub>>,<x<sub>1</sub>,z<sub>3</sub>>,<x<sub>2</sub>,z<sub>3</sub>>} </p>
<p style="line-height: 150%" align="left" ><b>关系合成的关系图表示:</b> </p>
<p style="line-height: 150%" align="center" > <img border="0" src="Image/gxt10.gif" width="211" height="159">
<img border="0" src="Image/gxt11.gif" width="139" height="155"> </p>
<p style="line-height: 150%" align="left" ><b>关系合成的关系矩阵表示:</b> </p>
<div align="center">
<center>
<table border="0" width="575" height="136">
<tr>
<td width="286" align="center" height="64">
<div align="center">
<center>
<table border="0" width="63%" cellpadding="0" cellspacing="1">
<tr>
<td width="25%" rowspan="3">
<p align="center"><img src="Image/mr.gif" width="22" height="15">1=</td>
<td width="25%" style="border-left-style: solid" align="center">1</td>
<td width="25%" align="center">1</td>
<td width="25%" style="border-right-style: solid" align="center">1</td>
</tr>
<tr>
<td width="25%" style="border-left-style: solid" align="center">0</td>
<td width="25%" align="center">1</td>
<td width="25%" style="border-right-style: solid" align="center">0</td>
</tr>
<tr>
<td width="25%" style="border-left-style: solid" align="center">0</td>
<td width="25%" align="center">0</td>
<td width="25%" style="border-right-style: solid" align="center">0</td>
</tr>
</table>
</center>
</div>
</td>
<td width="287" align="center" height="64">
<div align="center">
<center>
<table border="0" width="69%" cellpadding="0" cellspacing="1">
<tr>
<td width="31%" rowspan="3">
<p align="center"><img src="Image/mr.gif" width="22" height="15">2=</td>
<td width="23%" style="border-left-style: solid" align="center">0</td>
<td width="23%" align="center">1</td>
<td width="23%" style="border-right-style: solid" align="center">1</td>
</tr>
<tr>
<td width="23%" style="border-left-style: solid" align="center">0</td>
<td width="23%" align="center">0</td>
<td width="23%" style="border-right-style: solid" align="center">1</td>
</tr>
<tr>
<td width="23%" style="border-left-style: solid" align="center">0</td>
<td width="23%" align="center">0</td>
<td width="23%" style="border-right-style: solid" align="center">0</td>
</tr>
</table>
</center>
</div>
</td>
</tr>
<tr><td width="286" align="center" height="64">
<div align="center">
<center>
<table border="0" width="194" cellpadding="0" cellspacing="1" height="59">
<tr>
<td width="48" rowspan="3" height="57">
<p align="center"><img src="Image/mr.gif" width="22" height="15">=</td>
<td width="48" style="border-left-style: solid" align="center" height="17">1</td>
<td width="48" align="center" height="17">1</td>
<td width="48" style="border-right-style: solid" align="center" height="17">1</td>
</tr>
<tr>
<td width="48" style="border-left-style: solid" align="center" height="18">0</td>
<td width="48" align="center" height="18">1</td>
<td width="48" style="border-right-style: solid" align="center" height="18">0</td>
</tr>
<tr>
<td width="48" style="border-left-style: solid" align="center" height="18">0</td>
<td width="48" align="center" height="18">0</td>
<td width="48" style="border-right-style: solid" align="center" height="18">0</td>
</tr>
</table>
</center>
</div>
</td><td width="287" align="center" height="64">
<table border="0" width="228" cellpadding="0" cellspacing="1" height="59">
<tr>
<td width="90" rowspan="3" height="57">
<p align="center">M<sub>R1</sub>·M<sub>R2</sub>=</td>
<td width="46" style="border-left-style: solid" align="center" height="17">1</td>
<td width="46" align="center" height="17">1</td>
<td width="47" style="border-right-style: solid" align="center" height="17">2</td>
⌨️ 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 + -