## 4 Experiments
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \(\alpha\) & **10** & **10** & **15** & **20** & **40** & **80** & **100** & **120** \\  & \(\beta\) & **20** & **40** & **40** & **40** & **80** & **100** & **100** & **100** \\ \hline \multirow{4}{*}{**S**} & \multirow{4}{*}{.ind file} & gaps & \(582,901\) & \(582,901\) & \(578,919\) & \(576,872\) & \(573,801\) & \(572,282\) & \(571,961\) & \(571,808\) \\  & & reserved bytes & \(42,945\) & \(42,945\) & \(31,128\) & \(25,252\) & \(16,671\) & \(12,538\) & \(11,769\) & \(11,252\) \\  & & back pointers & \(85,387\) & \(85,387\) & \(61,864\) & \(50,167\) & \(33,086\) & \(24,857\) & \(23,327\) & \(22,297\) \\ \cline{2-11} \multirow{4}{*}{**S**} & \multirow{4}{*}{.for file} & stoppers & \(46,233\) & \(46,233\) & \(46,233\) & \(46,233\) & \(46,233\) & \(46,233\) & \(46,233\) & \(46,233\) \\  & & stem variants & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) & \(42,598\) \\  & & NAN words & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) & \(82,541\) \\  & & stop words & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) & \(334,933\) \\ \cline{2-11} \multirow{4}{*}{**S**} & \multirow{4}{*}{.voc file} & words & \(175,933\) & \(175,933\) & \(175,933\) & \(175,933\) & \(175,933\) & \(175,933\) & \(175,933\) & \(175,933\) \\  & & Huffman trees & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) & \(246,820\) \\  & & _FP_ & \(35,756\) & \(23,571\) & \(23,571\) & \(23,585\) & \(15,576\) & \(12,189\) & \(12,189\) & \(12,189\) & \(12,189\) \\  & & sorted stems & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) \\  & & _FI_ & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) & \(36,836\) \\ \cline{2-11}  & & **total** & \(1,749,719\) & \(1,737,534\) & \(1,698,212\) & \(1,678,606\) & \(1,641,864\) & \(1,624,596\) & \(1,621,976\) & \(1,620,276\) \\ \cline{2-11} \multirow{4}{*}{**S**} & \multirow{4}{*}{.ind file} & **compression ratio** & \(42.91\) & \(42.61\) & \(41.65\) & \(41.16\) & \(40.26\) & \(39.84\) & \(39.78\) & \(39.73\) \\ \cline{2-11}  & & \multirow{2}{*}{.ind file} & \(711,233\) & \(711,233\) & \(671,911\) & \(652,291\) & \(623,558\) & \(609,677\) & \(607,057\) & \(605,357\) \\  & & \multirow{2}{*}{.for file} & \(506,306\) & \(506,306\) & \(506,306\) & \(506,306\) & \(506,306\) & \(506,306\) & \(506,306\) & \(506,306\) \\  & & \multirow{2}{*}{.voc file} & \(180,365\) & \(168,200\) & \(168,137\) & \(168,188\) & \(160,151\) & \(156,748\) & \(156,694\) & \(156,659\) \\ \cline{2-11} \multirow{4}{*}{**S**} & **total** & \(1,397,904\) & \(1,385,739\) & \(1,346,354\) & \(1,326,785\) & \(1,290,015\) & \(1,272,731\) & \(1,270,057\) & \(1,268,322\) \\ \cline{2-11}  & & **compression ratio** & \(34.28\) & \(33.98\) & \(33.02\) & \(32.54\) & \(31.64\) & \(31.21\) & \(31.15\) & \(31.10\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: PISI space breakdown when performed on bible.txt file. The space is given in bytes (memory consumption in upper part of the table and the disk storage consumption in lower part of the table). The compression ratio refers to size of the original file. Figure 4: PISI: Compression ratio / Snippet time trade-off corresponding to different values of the parameters \(\alpha\) and \(\beta\). The time is stated in microseconds per character. Single curves represent different number of words that are decompressed to compose a snippet. Figure 5 shows a trade-off between the compression ratio and the time needed to extract a snippet. The snippet time includes search time and a time needed to extract a certain number of words (10, 100, 1000 and the whole file). We tested so-called bag-of-words search with four words randomly chosen of the indexed text.