Discrete Math - Proving Distributive Laws for Sets by induction












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I'm working on doing a proof by induction on this question:



Use induction to prove that if $X_1, . . . , X_n$ and $X$ are sets, then
$X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$.



I've shown the basis case:



$X∩X_1 = X∩X_1$



But I'm having difficulty proving the $n + 1$ case. This is my work so far:



Assume $X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$



Show $X∩(X_1∪X_2∪· · ·∪X_n∪X_{n+1}) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)∪(X∩X_{n+1})$



I'm not sure what I'm allowed to do from here. Where can I use the induction hypothesis?










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  • $begingroup$
    Please use MathJax to format your question correctly
    $endgroup$
    – Ankit Kumar
    Jan 11 at 4:57
















1












$begingroup$


I'm working on doing a proof by induction on this question:



Use induction to prove that if $X_1, . . . , X_n$ and $X$ are sets, then
$X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$.



I've shown the basis case:



$X∩X_1 = X∩X_1$



But I'm having difficulty proving the $n + 1$ case. This is my work so far:



Assume $X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$



Show $X∩(X_1∪X_2∪· · ·∪X_n∪X_{n+1}) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)∪(X∩X_{n+1})$



I'm not sure what I'm allowed to do from here. Where can I use the induction hypothesis?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Please use MathJax to format your question correctly
    $endgroup$
    – Ankit Kumar
    Jan 11 at 4:57














1












1








1





$begingroup$


I'm working on doing a proof by induction on this question:



Use induction to prove that if $X_1, . . . , X_n$ and $X$ are sets, then
$X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$.



I've shown the basis case:



$X∩X_1 = X∩X_1$



But I'm having difficulty proving the $n + 1$ case. This is my work so far:



Assume $X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$



Show $X∩(X_1∪X_2∪· · ·∪X_n∪X_{n+1}) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)∪(X∩X_{n+1})$



I'm not sure what I'm allowed to do from here. Where can I use the induction hypothesis?










share|cite|improve this question











$endgroup$




I'm working on doing a proof by induction on this question:



Use induction to prove that if $X_1, . . . , X_n$ and $X$ are sets, then
$X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$.



I've shown the basis case:



$X∩X_1 = X∩X_1$



But I'm having difficulty proving the $n + 1$ case. This is my work so far:



Assume $X∩(X_1∪X_2∪· · ·∪X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)$



Show $X∩(X_1∪X_2∪· · ·∪X_n∪X_{n+1}) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n) = (X∩X_1)∪(X∩X_2)∪· · ·∪(X∩X_n)∪(X∩X_{n+1})$



I'm not sure what I'm allowed to do from here. Where can I use the induction hypothesis?







discrete-mathematics elementary-set-theory induction proof-explanation






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edited Feb 19 at 11:41









Heptapod

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asked Jan 11 at 4:49









ShellG44ShellG44

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  • $begingroup$
    Please use MathJax to format your question correctly
    $endgroup$
    – Ankit Kumar
    Jan 11 at 4:57


















  • $begingroup$
    Please use MathJax to format your question correctly
    $endgroup$
    – Ankit Kumar
    Jan 11 at 4:57
















$begingroup$
Please use MathJax to format your question correctly
$endgroup$
– Ankit Kumar
Jan 11 at 4:57




$begingroup$
Please use MathJax to format your question correctly
$endgroup$
– Ankit Kumar
Jan 11 at 4:57










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Tip show: $Xcap(Ycup X_{n+1})=(Xcup Y)cap(Xcup X_{n+1})$ where $Y=X_1cupcdotscup X_n$






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    $begingroup$

    Tip show: $Xcap(Ycup X_{n+1})=(Xcup Y)cap(Xcup X_{n+1})$ where $Y=X_1cupcdotscup X_n$






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      $begingroup$

      Tip show: $Xcap(Ycup X_{n+1})=(Xcup Y)cap(Xcup X_{n+1})$ where $Y=X_1cupcdotscup X_n$






      share|cite|improve this answer









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        $begingroup$

        Tip show: $Xcap(Ycup X_{n+1})=(Xcup Y)cap(Xcup X_{n+1})$ where $Y=X_1cupcdotscup X_n$






        share|cite|improve this answer









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        Tip show: $Xcap(Ycup X_{n+1})=(Xcup Y)cap(Xcup X_{n+1})$ where $Y=X_1cupcdotscup X_n$







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        answered Jan 11 at 4:54









        Graham KempGraham Kemp

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