📄 content-1-1-2.htm
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<div align="center">0</div>
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<p style="line-height: 150%" ><b> 例</b> ：灯泡坏了或是开关坏了。<br>
设：P：灯泡坏了；Q：开关坏了。<br>
则原命题为： P<img src="image/xiqu.gif" width="9" height="15">Q。</p>
<p style="line-height: 150%" ><b><font color="#FF0000"> 注：</font></b>并非所有的“或”都表示“析取”，例如，我向西走或向东走。<br>
这种“或”称为“排斥或”、“异或”，其特点是：当量个命题的政治不同时原命题的真值为“1”。可构造真值表如下：</p>
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<center>
<table width="23%" border="1">
<tr>
<td width="30%">
<div align="center">P</div>
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<td width="30%">
<div align="center">Q</div>
</td>
<td width="40%">
<div align="center">P<span lang="EN-US" style="font-size:10.5pt;mso-bidi-font-size:
12.0pt;font-family:"Times New Roman";mso-fareast-font-family:宋体;mso-font-kerning:
1.0pt;mso-ansi-language:EN-US;mso-fareast-language:ZH-CN;mso-bidi-language:
AR-SA"><span style="mso-text-raise:-2.0pt"><!--[if gte vml 1]><v:shapetype
id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t"
path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f">
<v:stroke joinstyle="miter"/>
<v:formulas>
<v:f eqn="if lineDrawn pixelLineWidth 0"/>
<v:f eqn="sum @0 1 0"/>
<v:f eqn="sum 0 0 @1"/>
<v:f eqn="prod @2 1 2"/>
<v:f eqn="prod @3 21600 pixelWidth"/>
<v:f eqn="prod @3 21600 pixelHeight"/>
<v:f eqn="sum @0 0 1"/>
<v:f eqn="prod @6 1 2"/>
<v:f eqn="prod @7 21600 pixelWidth"/>
<v:f eqn="sum @8 21600 0"/>
<v:f eqn="prod @7 21600 pixelHeight"/>
<v:f eqn="sum @10 21600 0"/>
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<v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/>
<o:lock v:ext="edit" aspectratio="t"/>
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o:title=""/>
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<img src="image/renyi.gif" v:shapes="_x0000_i1025" width="9" height="11"> <!--[if gte mso 9]><xml>
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Q</div>
</td>
</tr>
<tr>
<td width="30%" align="center">
<div align="center">0</div>
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0
</td>
<td width="40%" align="center">
<div align="center">1</div>
</td>
</tr>
<tr>
<td width="30%" align="center">
<div align="center">0</div>
</td>
<td width="30%" align="center">
1
</td>
<td width="40%" align="center">
<div align="center">1</div>
</td>
</tr>
<tr>
<td width="30%" align="center">
<div align="center">1</div>
</td>
<td width="30%" align="center">
<div align="center">0</div>
</td>
<td width="40%" align="center">
<div align="center">0</div>
</td>
</tr>
<tr>
<td width="30%" align="center">
<div align="center">1</div>
</td>
<td width="30%" align="center">
1
</td>
<td width="40%" align="center">
<div align="center">1</div>
</td>
</tr>
</table>
</center>
</div>
<p style="line-height: 150%" > </p>
<p style="line-height: 150%" >
<b>4、蕴含(<img src="image/yunhan.gif" width="15" height="9">),
如果…，则…</b><br>
定义：给定两个命题P、Q，命题 “若P，则Q”称为“P蕴含Q”记为： P<img src="image/yunhan.gif" width="15" height="9">Q，<br>
当且仅当P为真Q为假时P<img src="image/yunhan.gif" width="15" height="9">Q为假，<br>
其中：P称为蕴含前件、条件、前提，Q称为后件、结果、结论。<br>
其定义可用如下真值表表示: </p>
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<center>
<table width="23%" border="1">
<tr>
<td width="30%">
<div align="center">P</div>
</td>
<td width="30%">
<div align="center">Q</div>
</td>
<td width="40%">
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