% Time-stamp: <Sunday 29 Jan 2006 11:55:42pm EST yoshi@flare>
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\section{Notation and terminology}
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\label{sec:notation}

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The essential notation and terminology used throughout this paper are as follows.
\begin{itemize}
\item $U$: key universe. $|U| = u$.
\item $S$: actual static key set. $S \subset U$, $|S| = n \ll u$.
\item $h: U \to M$ is a hash function that maps keys from a universe $U$ into
a given range $M = \{0,1,\dots,m-1\}$ of integer numbers.
\item $h$ is a perfect hash function if it is one-to-one on~$S$, i.e., if
  $h(k_1) \not = h(k_2)$ for all $k_1 \not = k_2$ from $S$.
\item $h$ is a minimal perfect hash function (MPHF) if it is one-to-one on~$S$ 
  and $n=m$. 
\end{itemize}