Differences
This shows you the differences between two versions of the page.
Next revision | Previous revision | ||
hypercube_graph [2014/02/10 23:10] nikolaj created |
hypercube_graph [2014/03/21 11:11] (current) |
||
---|---|---|---|
Line 1: | Line 1: | ||
===== Hypercube graph ===== | ===== Hypercube graph ===== | ||
==== Set ==== | ==== Set ==== | ||
- | | @#88DDEE: $ n\in\mathbb N, n\ge 1 $ | | + | | @#55CCEE: context | @#55CCEE: $ n\in\mathbb N, n\ge 1 $ | |
- | | @#DDDDDD: $ V\equiv \{0,1\}^n $ | | + | | @#DDDDDD: range | @#DDDDDD: $ V\equiv \{0,1\}^n $ | |
- | | @#FFBB00: $Q_n\equiv \langle V,E\rangle$ | | + | | @#FFBB00: definiendum | @#FFBB00: $Q_n\equiv \langle V,E\rangle$ | |
- | | @#DDDDDD: $ k\in\mathbb N,1\le k\le n $ | | + | | @#DDDDDD: range | @#DDDDDD: $ k\in\mathbb N,1\le k\le n $ | |
- | | @#FFFDDD: $ v,w\in V $ | | + | | @#FFFDDD: for all | @#FFFDDD: $ v,w\in V $ | |
- | | @#55EE55: $ \{v,w\}\in E\leftrightarrow \exists!k.\ \pi_k(v)\neq\pi_k(w) $ | | + | | @#55EE55: postulate | @#55EE55: $ \{v,w\}\in E\leftrightarrow \exists!k.\ \pi_k(v)\neq\pi_k(w) $ | |
==== Discussion ==== | ==== Discussion ==== | ||
The Hypercube graph, also called n-cube, has vertices all n-tuples of 0's and 1's and two such vertices are connected iff they differ in one coordinate. | The Hypercube graph, also called n-cube, has vertices all n-tuples of 0's and 1's and two such vertices are connected iff they differ in one coordinate. | ||
+ | Since strings with 0's and 1's of length $n$ encode the subsetsets of an n-element set, we have $|V|=2^n$. And since for each n-tuple there $n$ ways to differ from it by one digit, there are $\frac{1}{2}2^n\cdot n$ vertices. | ||
+ | |||
+ | It is also the Hesse diagram of a Boolean lattice, the powerset with elements connected iff they differ by one element. | ||
+ | === Examples === | ||
E.g. $V(Q_2)=\{\langle 0,0\rangle,\langle 0,1\rangle,\langle 1,0\rangle,\langle 1,1\rangle\}$ and there are all but the diagonal relations are edges in the graph. Clearly $Q_n$ is just a square. | E.g. $V(Q_2)=\{\langle 0,0\rangle,\langle 0,1\rangle,\langle 1,0\rangle,\langle 1,1\rangle\}$ and there are all but the diagonal relations are edges in the graph. Clearly $Q_n$ is just a square. | ||
==== Parents ==== | ==== Parents ==== | ||
=== Subset of === | === Subset of === | ||
- | [[Undirected graph]] | + | [[k-regular graph]], [[Bipartite graph]] |
- | === Requirements === | + | === Context === |
[[Cartesian product]] | [[Cartesian product]] |