MHB Finite Group Inverses: Proving $N_{ABC}=N_{CBA}$

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The discussion presents a challenge involving finite groups and the concept of counting specific triples within subsets. It defines \( N_{UVW} \) as the number of triples \( (x,y,z) \) from subsets \( U, V, W \) of a finite group \( G \) that multiply to the group's identity element \( e \). The main goal is to prove that for three pairwise disjoint sets \( A, B, C \) covering \( G \), the equality \( N_{ABC} = N_{CBA} \) holds. A hint is provided to assist in the proof, emphasizing the algebraic properties of the group. The discussion centers on the relationships between the subsets and their contributions to the count of valid triples.
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Hi,

I bring a new algebraic challenge ;)

Let $G$ be a finite group and $U,V,W\subset G$ arbitrary subsets of $G$.
We will denote $N_{UVW}$ the number of triples $(x,y,z)\in U\times V \times W$ such that $xyz$ is the unity of $G$, say $e$.
Now suppose we have three pairwise disjoint sets $A,B,C$ such that $G=A\cup B \cup C$

Prove that $N_{ABC}=N_{CBA}$.
 
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A hint:

Start proving that for arbitrary $U,V\subset G$
$N_{UVG}=|U||V|$
and for arbitraty $U,V,W\subset G$
$N_{UVW}=N_{WUV}=N_{VWU}$
 
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