[Math] Perfect matching in k-cubes

graph theory

I want to show that every k-cube has a perfect matching for $ k \geqslant 1 $. (A k-cube is a graph whose vertices are labeled by k-tuples consisting of $ 0 $ and $1$ , and each two adjacent vertices are different in only one digit.)

According to Tutte's theorem, our graph has a perfect matching $\iff$ $$o(G-S) \leqslant \vert S \vert $$ for all $$S\subset V$$ where $o$ denotes the number of components with odd number of vertices, but the problem is that for arbitrary k the only way is to check all possible subsets $ S $ which is impractical and irrational. I don't think Tutte's theorem is efficient here.

Best Answer

Use the representation of the $k$-cube as a binary vector of length $k$. For each set of binary digits $b2,\ldots,b_k$ you have an edge between $(0,b_2,\ldots,b_k)$ and $(1,b_2,\ldots,b_k)$.

Now show that this constitutes a perfect matching.

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