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Suppose <math>L \subseteq X \times Y \times Z\!</math> is an arbitrary triadic relation and consider the information about <math>L\!</math> that is provided by collecting its dyadic projections.  To formalize this information define the ''projective triple'' of <math>L\!</math> as follows:
 
Suppose <math>L \subseteq X \times Y \times Z\!</math> is an arbitrary triadic relation and consider the information about <math>L\!</math> that is provided by collecting its dyadic projections.  To formalize this information define the ''projective triple'' of <math>L\!</math> as follows:
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{| align="center" cellspacing="8" width="90%"
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| <math>\operatorname{Proj}^{(2)}(L) ~=~ (\operatorname{proj}_{12}(L), \operatorname{proj}_{13}(L), \operatorname{proj}_{23}(L)).</math>
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|}
    
<pre>
 
<pre>
Proj (R)  =  Pr2(R)  =  <Pr12(R), Pr13(R), Pr23(R)>.
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If R is visualized as a solid body in the 3 dimensional space XxYxZ, then Proj (R) can be visualized as the arrangement or ordered collection of shadows it throws on the XY, XZ, and YZ planes, respectively.
 
If R is visualized as a solid body in the 3 dimensional space XxYxZ, then Proj (R) can be visualized as the arrangement or ordered collection of shadows it throws on the XY, XZ, and YZ planes, respectively.
  
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