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Proof

G$ ^{*}$H $ ^{*\bot}=\left[\begin{array}{cc}P & I\end{array}\right]\left[\begin{array}{rr}I \\  -P\end{array}\right]=P-P=0$
This works because our dual code is orthogonal to our space of codewords. And since H forms a basis of our dual code, this technique guarantees our dual space will be orthogonal as well to C.

This brings us to the generalized definition of a Hamming Code using the concept of a parity check matrix.

Let r be a positive integer and $ n:=\frac{q^r-1}{q-1}$. Consider any parity check matrix H whose columns are r-tuples, each of which cannot be represented as a scalar multiple of each other. Then the Hamming code Ham(r,q) consists of the vectors c for which c$ \cdot$H$ ^{\top}=$0.

A little linear algebra calculation revolving around sizes of the matrices involved gives $ r=n-k$, (from the dimension of the solution of the nullspace).

The Hamming code is a perfect 1-error correcting code.



Bill Cherowitzo 2001-12-11