Difference between revisions of "Set subtraction"

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==Definition==
 
==Definition==
Given two sets, {{M|A}} and {{M|B}} we define ''set subtraction'' as follows:
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Given two sets, {{M|A}} and {{M|B}} we define ''set subtraction'' ({{AKA}}: ''relative complement''{{rMTH}}) as follows:
 
* {{M|1=A-B=\{x\in A\vert x\notin B\} }}
 
* {{M|1=A-B=\{x\in A\vert x\notin B\} }}
===Equivalent definitions===
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===Alternative forms===
 
{{Begin Inline Theorem}}
 
{{Begin Inline Theorem}}
 
* {{M|1=A-B=(A^c\cup B)^c}}
 
* {{M|1=A-B=(A^c\cup B)^c}}
 
{{Begin Inline Proof}}
 
{{Begin Inline Proof}}
{{Todo|Be bothered to do this}}
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{{Requires proof|Be bothered to do this}}
 
{{End Proof}}{{End Theorem}}
 
{{End Proof}}{{End Theorem}}
==Other names==
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==Terminology==
* Relative complement
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* '''Relative complement'''<ref name="MTH"/>
** This comes from the fact that the complement of a subset of {{M|X}}, {{M|A}} is just {{M|X-A}}
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** This comes from the idea of a [[complement]] of a subset of {{M|X}}, say {{M|A}} being just {{M|X-A}}, so if we have {{M|A,B\in\mathcal{P}(X)}} then {{M|A-B}} can be thought of as the complement of {{M|B}} if you consider it relative (to be in) {{M|A}}.
 
==Notations==
 
==Notations==
 
Other notations include:
 
Other notations include:
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==References==
 
==References==
 
<references/>
 
<references/>
{{Todo|Find references}}
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{{Set operations navbox|plain}}
 
{{Definition|Set Theory}}
 
{{Definition|Set Theory}}
 
{{Theorem Of|Set Theory}}
 
{{Theorem Of|Set Theory}}
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[[Category:Set operations]]

Latest revision as of 00:48, 21 March 2016

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Definition

Given two sets, A and B we define set subtraction (AKA: relative complement[1]) as follows:

  • AB={xA|xB}

Alternative forms

[Expand]

  • AB=(AcB)c

Terminology

  • Relative complement[1]
    • This comes from the idea of a complement of a subset of X, say A being just XA, so if we have A,BP(X) then AB can be thought of as the complement of B if you consider it relative (to be in) A.

Notations

Other notations include:

  • AB

Trivial expressions for set subtraction

[Expand]

Claim: (AB)C=A(BC)


See also

References

  1. Jump up to: 1.0 1.1 Measure Theory - Paul R. Halmos