<div dir="ltr"><p class=""><span lang="EN-US">Dear all:</span></p>
<p class=""><span lang="EN-US">My name is Xudong Zhang, from Peking
University. I'm very interested in the Project: Posting list encoding
improvements, and I have had some experience on encoding, and so I want to be
involved in the project.</span></p>
<p class=""><span lang="EN-US">About the project</span><span style="font-family:宋体">，</span><span lang="EN-US">I have a question
to consult:</span></p>
<p class=""><span lang="EN-US">What's the main goal of the improvement of
the speed for the encoding and decoding of posting lists? Is it OK to increase
the encoding/decoding speed greatly with the slight loss of compression?</span></p>
<p class=""><span lang="EN-US">Below is about my personal information. I'm
a master student from Peking University, Beijing, China. My research area is
search engine and web mining, and I've been focusing on compression algorithms
of posting lists in search engines since last February. I have proposed a novel
decoding algorithm called SIMD-PFORDelta, which exploit SIMD instructions in
PFORDelta. It is fast and can achieve good compression ratio. Recently, I also
did some experiments to test the state-of-the-art and proposed encoding
algorithms of posting lists. We used our own search engine called PARADISE and
the datasets are GOV2(25 million docs) and ClueWeb09B(50 million docs). Below
is some experimental results of docIDs’ gap sequence on ClueWeb09B, which is
similar to Lemire's results[1] (The implementation of SIMD_pfor_delta is
somewhat different to that in Lemire's paper):</span></p>
<p class=""><span lang="EN-US"> </span></p>
<table class="" border="1" cellspacing="0" cellpadding="0" style="border-collapse:collapse;border:none">
<tbody><tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border:1pt solid windowtext;padding:0cm 5.4pt;height:13.5pt">
<p class=""><a name="RANGE!B10:E27"><span lang="EN-US">Algorithm Name</span></a><span lang="EN-US"></span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:solid solid solid none;border-top-color:windowtext;border-right-color:windowtext;border-bottom-color:windowtext;border-top-width:1pt;border-right-width:1pt;border-bottom-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">Compression Speed(M/s)</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:solid solid solid none;border-top-color:windowtext;border-right-color:windowtext;border-bottom-color:windowtext;border-top-width:1pt;border-right-width:1pt;border-bottom-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">Decompression Speed(M/s)</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:solid solid solid none;border-top-color:windowtext;border-right-color:windowtext;border-bottom-color:windowtext;border-top-width:1pt;border-right-width:1pt;border-bottom-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">Compression Ratio</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">simple9</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">88.2749297</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">500.8305639</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">16.72%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">simple16</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">51.29381855</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">488.0998879</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">15.55%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">var_byte</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">492.9379145</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">519.1921354</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">26.02%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">group_var_byte</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">243.7189985</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">501.3713526</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">31.76%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">group_var_byte_incomp_unary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">124.5200775</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">501.8188062</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">28.77%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">group_var_byte_comp_unary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">123.1249031</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">461.8294703</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">28.70%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD_group_var_byte</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">240.296232</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">793.0340184</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">31.76%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD_group_var_byte_incomp_unary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">126.3003402</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1325.49703</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">28.77%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD_group_var_byte_comp_unary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">126.3347572</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1128.968014</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">28.70%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">packed_binary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">252.6257354</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1151.000784</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">27.55%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD_packed_binary</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">254.2433557</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1507.316133</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">27.55%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">pfor_delta</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">26.99031483</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1026.717585</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">19.53%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD_pfor_delta</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">27.23024567</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">1580.111396</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">19.53%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">rice</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">68.74742448</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">79.16529964</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">15.77%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">k_gamma</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">172.9461803</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">242.8787555</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">15.24%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">gamma_opt</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">61.7750133</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">59.30571281</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">14.91%</span></p>
</td>
</tr>
<tr style="height:13.5pt">
<td width="289" nowrap valign="top" style="width:217pt;border-style:none solid solid;border-right-color:windowtext;border-bottom-color:windowtext;border-left-color:windowtext;border-right-width:1pt;border-bottom-width:1pt;border-left-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">SIMD__kgamma</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">174.1829249</span></p>
</td>
<td width="173" nowrap valign="top" style="width:130pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">262.0594328</span></p>
</td>
<td width="155" nowrap valign="top" style="width:116pt;border-style:none solid solid none;border-bottom-color:windowtext;border-bottom-width:1pt;border-right-color:windowtext;border-right-width:1pt;padding:0cm 5.4pt;height:13.5pt">
<p class=""><span lang="EN-US">15.24%</span></p></td></tr></tbody></table><p class=""><br></p>
<p class=""><span lang="EN-US">Thank you very much!</span></p>
<p class=""><span lang="EN-US">P.S. In D. Lemire's paper: Decoding
billions of integers per second through vectorization(CORR'12), SIMD-PORDelta
can outperforms VSEncoding w.r.t decoding speed, while remaining nearly the
same compression ratio, namely, bits/int.</span></p>
<p class=""><span lang="EN-US">[1] D. Lemire et al. Decoding billions of
integers per second through vectorization, CORR’12, <a href="http://arxiv.org/abs/1209.2137">http://arxiv.org/abs/1209.2137</a></span></p>
<p class=""><span lang="EN-US">Best wishes,</span></p>
<p class=""><span lang="EN-US">Xudong Zhang</span></p><div><br></div>-- <br>---------------------------<div><br></div><div><span style="color:rgb(136,136,136);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">Xudong Zhang<br>
+86-13488695609<br>Team of Search Engine and Web Mining<br>School of Electronic Engineering and Computer Science<br>Peking University, Beijing, 100871, P.R.China</span></div>
</div>