deletions | additions       diff --git a/bits4.tex b/bits4.tex  index dca293d..ab1fe11 100644  --- a/bits4.tex  +++ b/bits4.tex 
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\]  where $p(x,y,z)=x+y+z$.  \end{Example}  Verify that the new bit $p(x,y,z)$ is the parity bit.  \begin{Exercise}  Verify that the new bit $p(x,y,z)$ is the parity bit.  \end{Exercise}  \begin{Example} An extremely useful boolean function, is the one that recognize if a vector of bits is the null vectors, that is $(0,\ldots,0)$. This function returns $1$ if the vector is null, $0$ otherwise. We observed (see \ref{XorIsNice}) that the multiplications of bits has the same truth table of the $\AND$ operator. So we have $1$ if each bit is $1$, $0$ otherwise. That is the opposite that we want. Adding $1$ we have the function (see \ref{Not}). If $n=3$ we have where $z(x,y,z)=xyz+1$.  \end{Example}