9 lines
1.6 KiB
TeX
9 lines
1.6 KiB
TeX
% -*- root: main.tex -*-
|
|
\section{Notation}
|
|
\label{sec:notation}
|
|
|
|
The following notation is used to reason about the sketching of world membership for a given tuple. A given sketch $\sketch$ can be viewed as a matrix with $\sketchRows$ rows and $\sketchCols$ columns. Each row of $\sketch$ is an estimation of the of $\kDom$ frequency for the given tuple represented by $\sketch$ across all possible worlds. The $\kDom$ values for a given world $\wVec$ \AR{I do not like this notation. I prefer vectors being typeset in bold, i.e. $\mathbf{w}$. $\wVec$ is good for writing on the board but it is more standard to bold vectors in linear algebra. Also the $\kDom$ values are not binned by $\sketchHash{i}$ but the actual $\wVec$s are.} are binned by a pairwise independent hash function $\sketchHash{i}$, where for each $i, j \in \sketchRows \text{ s.t. } i \neq j, \sketchHash{i}$ is independent of $\sketchHash{j}$. Thus each row can be viewed as an independent estimation. When a $\kDom$ value is binned, it is first multiplied by the ouput of the $i^{th}$ row's polarity function $\sketchPolar$. The resulting computation is then added to the current value contained in the bin mapping.
|
|
|
|
When referring to Tuple Independent Databases (TIDB), a database $\relation$ contains $\numTup$ tuples, with $\numWorlds$ possible worlds $\pw$. $\pw$ is denoted as $\{0, 1\}^\numTup$, where a specific world $\wVec$ is defined as $\wVec \in \{0, 1\}^\numTup$. An indicator function $\wIndicator$ defined as $\wIndicator : \{0, 1\}^\numTup \rightarrow \kDom$ is used to determine the tuple's $\kDom$ annotation for a given world.
|
|
|