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1	Data Compression for use in the Short Messaging System / Datakompression för användning i Short Messaging Systemet Andersson, Måns January 2010 (has links) Data compression is a vast subject with a lot of different algorithms. All algorithms are not good at every task and this thesis takes a closer look on compression of small files in the range of 100-300 bytes having in mind that the compressed output are to be sent over the Short Messaging System (SMS). Some well-known algorithms are tested for compression ratio and two of them, the Algorithm Λ, and the Adaptive Arithmetic Coding, are chosen to get a closer understanding of and then implement in the Java language. Those implementations are tested alongside the first tested implementations and one of the algorithms are chosen to answer the question ”Which compression algorithm is best suited for compression of data for use in Short Messaging System messages?”. / Datakompression är ett brett område med ett stort antal olika algoritmer. Alla algoritmer är inte bra för alla tillfällen och denna rapport tittar i huvudsak på kompression av små filer i intervallet 100-300 byte tänkta att skickas komprimerade över SMS. Ett antal välkända algoritmers kompressionsgrad är testade och två av dem, Algorithm Λ och Adaptiv Aritmetisk Kodning, väljs ut och studeras närmre samt implementeras i Java. Dessa implementationer är sedan testade tillsammans med tidigare testade implementationer och en av algoritmerna väljs ut för att besvara frågan "Vilken kompressionsalgoritm är best lämpad för att komprimerad data för användning i SMS-meddelanden?". compression sms arithmetic lambda huffman lzw lz77 lz78 Fristående kurs Computer Sciences Datavetenskap (datalogi)
2	Musical Phrase Segmentation via Grammatical Induction Perkins, Reed James 06 April 2022 (has links) Procedural generation algorithms can infer rules based on a dataset of examples when each example is made up of labeled components. Unfortunately, musical sequences resist potential inclusion in these kinds of datasets because they lack explicit structural semantics. In order to algorithmically transform a musical sequence into a sequence of labeled components, a segmentation process is needed. We outline a solution to the challenge of musical phrase segmentation that uses grammatical induction algorithms, a class of algorithms which infer a context-free grammar from an input sequence. We study five different grammatical induction algorithms on three different datasets, one of which is introduced in this work. Additionally, we test how the performance of each algorithm varies when transforming musical sequences using viewpoint combinations. Our experiments show that the algorithm longestFirst achieves the best F1 scores across all three datasets, and that viewpoint combinations which include the duration viewpoint result in the best performance. grammtical induction LZ78 Sequitur context-free grammars phrase segmentation Physical Sciences and Mathematics
3	Contributions à la compression de données Pigeon, Steven January 2001 (has links) Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal. Codes universels Codes de Golomb Algorithmes Ondelettes Codes adaptatifs Compression LZ78 LZW Pseudo-ondelettes
4	Fast Low Memory T-Transform: string complexity in linear time and space with applications to Android app store security. Rebenich, Niko 27 April 2012 (has links) This thesis presents flott, the Fast Low Memory T-Transform, the currently fastest and most memory efficient linear time and space algorithm available to compute the string complexity measure T-complexity. The flott algorithm uses 64.3% less memory and in our experiments runs asymptotically 20% faster than its predecessor. A full C-implementation is provided and published under the Apache Licence 2.0. From the flott algorithm two deterministic information measures are derived and applied to Android app store security. The derived measures are the normalized T-complexity distance and the instantaneous T-complexity rate which are used to detect, locate, and visualize unusual information changes in Android applications. The information measures introduced present a novel, scalable approach to assist with the detection of malware in app stores. / Graduate Kolmogorov complexity Lempel Ziv T-codes flott Fast T-decomposition ftd mobile computing Lempel-Ziv complexity LZ complexity LZ78 LZ77 LZ76 LZW normalized information distance NID normalized compression distance NCD McCreight Ukkonen phylogenetics phylogenetic tree Gemini Droiddream Apple iOS iPhone iPad mobile phone open source Apache License 2.0

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