Question on a proof of no existance of monochromatic triangle in any tricoloring of edges of $K_{16}$












1












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Here is a question on the book "Problem -Solving Strategies" by Arthur Engel, with a provided solution:
enter image description here



enter image description here



In the solution, they partitioned the abelian group into 3 sets such that none of them is sum-free. However, in $A_3$, $(a+b+d) +(a+c+d)=b+c in A_3$.










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  • $begingroup$
    yes, sorry I just wanted to know the correct version
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:51










  • $begingroup$
    Ok! I edited it!
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:56
















1












$begingroup$


Here is a question on the book "Problem -Solving Strategies" by Arthur Engel, with a provided solution:
enter image description here



enter image description here



In the solution, they partitioned the abelian group into 3 sets such that none of them is sum-free. However, in $A_3$, $(a+b+d) +(a+c+d)=b+c in A_3$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    yes, sorry I just wanted to know the correct version
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:51










  • $begingroup$
    Ok! I edited it!
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:56














1












1








1





$begingroup$


Here is a question on the book "Problem -Solving Strategies" by Arthur Engel, with a provided solution:
enter image description here



enter image description here



In the solution, they partitioned the abelian group into 3 sets such that none of them is sum-free. However, in $A_3$, $(a+b+d) +(a+c+d)=b+c in A_3$.










share|cite|improve this question











$endgroup$




Here is a question on the book "Problem -Solving Strategies" by Arthur Engel, with a provided solution:
enter image description here



enter image description here



In the solution, they partitioned the abelian group into 3 sets such that none of them is sum-free. However, in $A_3$, $(a+b+d) +(a+c+d)=b+c in A_3$.







proof-verification graph-theory pigeonhole-principle






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edited Dec 12 '18 at 0:55







nafhgood

















asked Dec 12 '18 at 0:18









nafhgoodnafhgood

1,805422




1,805422












  • $begingroup$
    yes, sorry I just wanted to know the correct version
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:51










  • $begingroup$
    Ok! I edited it!
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:56


















  • $begingroup$
    yes, sorry I just wanted to know the correct version
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:51










  • $begingroup$
    Ok! I edited it!
    $endgroup$
    – nafhgood
    Dec 12 '18 at 0:56
















$begingroup$
yes, sorry I just wanted to know the correct version
$endgroup$
– nafhgood
Dec 12 '18 at 0:51




$begingroup$
yes, sorry I just wanted to know the correct version
$endgroup$
– nafhgood
Dec 12 '18 at 0:51












$begingroup$
Ok! I edited it!
$endgroup$
– nafhgood
Dec 12 '18 at 0:56




$begingroup$
Ok! I edited it!
$endgroup$
– nafhgood
Dec 12 '18 at 0:56










1 Answer
1






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0












$begingroup$

You are right. To correct the proof, move $a+c+d$ to $A_2$ and $b+c+d$ to $A_3$. Is everything all right now?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
    $endgroup$
    – nafhgood
    Dec 12 '18 at 15:03










  • $begingroup$
    I don't know.$ $
    $endgroup$
    – bof
    Dec 12 '18 at 15:10













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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









0












$begingroup$

You are right. To correct the proof, move $a+c+d$ to $A_2$ and $b+c+d$ to $A_3$. Is everything all right now?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
    $endgroup$
    – nafhgood
    Dec 12 '18 at 15:03










  • $begingroup$
    I don't know.$ $
    $endgroup$
    – bof
    Dec 12 '18 at 15:10


















0












$begingroup$

You are right. To correct the proof, move $a+c+d$ to $A_2$ and $b+c+d$ to $A_3$. Is everything all right now?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
    $endgroup$
    – nafhgood
    Dec 12 '18 at 15:03










  • $begingroup$
    I don't know.$ $
    $endgroup$
    – bof
    Dec 12 '18 at 15:10
















0












0








0





$begingroup$

You are right. To correct the proof, move $a+c+d$ to $A_2$ and $b+c+d$ to $A_3$. Is everything all right now?






share|cite|improve this answer









$endgroup$



You are right. To correct the proof, move $a+c+d$ to $A_2$ and $b+c+d$ to $A_3$. Is everything all right now?







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 12 '18 at 0:48









bofbof

51.7k558120




51.7k558120












  • $begingroup$
    Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
    $endgroup$
    – nafhgood
    Dec 12 '18 at 15:03










  • $begingroup$
    I don't know.$ $
    $endgroup$
    – bof
    Dec 12 '18 at 15:10




















  • $begingroup$
    Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
    $endgroup$
    – nafhgood
    Dec 12 '18 at 15:03










  • $begingroup$
    I don't know.$ $
    $endgroup$
    – bof
    Dec 12 '18 at 15:10


















$begingroup$
Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
$endgroup$
– nafhgood
Dec 12 '18 at 15:03




$begingroup$
Is there an algorithm to partition a group into disjoint unions of subsets that are sum free?
$endgroup$
– nafhgood
Dec 12 '18 at 15:03












$begingroup$
I don't know.$ $
$endgroup$
– bof
Dec 12 '18 at 15:10






$begingroup$
I don't know.$ $
$endgroup$
– bof
Dec 12 '18 at 15:10




















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