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Constraint satisfaction for inductive logic programming
Chovanec, Andrej ; Barták, Roman (advisor) ; Železný, Filip (referee)
Inductive logic programming is a discipline investigating invention of clausal theories from observed examples such that for given evidence and background knowledge we are finding a hypothesis covering all positive examples and excluding all negative ones. In this thesis we extend an existing work on template consistency to general consistency. We present a three-phase algorithm DeMeR decomposing the original problem into smaller subtasks, merging all subsolutions together yielding a complete solution and finally refining the result in order to get a compact final hypothesis. Furthermore, we focus on a method how each individual subtask is solved and we introduce a generate-and-test method based on the probabilistic history-driven approach for this purpose. We analyze each stage of the proposed algorithms and demonstrate its impact on a runtime and a hypothesis structure. In particular, we show that the first phase of the algorithm concentrates on solving the problem quickly at the cost of longer solutions whereas the other phases refine these solutions into an admissible form. Finally, we prove that our technique outperforms other algorithms by comparing its results for identifying common structures in random graphs to existing systems.
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Digital Reconstructed Radiography
Chovanec, Andrej ; Pelikán, Josef (advisor) ; Krajíček, Václav (referee)
X-ray examination is an important part of the medical treatment. Despite all the advantages it introduces, it brings some limitations as well. In the present work we describe a technique that from the acquired CT data reconstructs a digital x-ray image and removes some drawbacks of traditional x-ray screening. Among the most significant improvements over the classical radiography belong generation of the screen from very arbitrary angle and interactive rotation of the image in real-time. In order to obtain the most realistic final image, we put the emphasis on the accurate simulation of physical properties of the x-ray radiation. We also try to get as low computational time needed to gain one image as possible. For this purpose we present a parallelization model that decomposes the required work of some components into several processors' cores and thus noticeably decreases the running time of the algorithm.
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Constraint satisfaction for inductive logic programming
Chovanec, Andrej ; Barták, Roman (advisor) ; Železný, Filip (referee)
Inductive logic programming is a discipline investigating invention of clausal theories from observed examples such that for given evidence and background knowledge we are finding a hypothesis covering all positive examples and excluding all negative ones. In this thesis we extend an existing work on template consistency to general consistency. We present a three-phase algorithm DeMeR decomposing the original problem into smaller subtasks, merging all subsolutions together yielding a complete solution and finally refining the result in order to get a compact final hypothesis. Furthermore, we focus on a method how each individual subtask is solved and we introduce a generate-and-test method based on the probabilistic history-driven approach for this purpose. We analyze each stage of the proposed algorithms and demonstrate its impact on a runtime and a hypothesis structure. In particular, we show that the first phase of the algorithm concentrates on solving the problem quickly at the cost of longer solutions whereas the other phases refine these solutions into an admissible form. Finally, we prove that our technique outperforms other algorithms by comparing its results for identifying common structures in random graphs to existing systems.
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|
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Digital Reconstructed Radiography
Chovanec, Andrej ; Krajíček, Václav (referee) ; Pelikán, Josef (advisor)
X-ray examination is an important part of the medical treatment. Despite all the advantages it introduces, it brings some limitations as well. In the present work we describe a technique that from the acquired CT data reconstructs a digital x-ray image and removes some drawbacks of traditional x-ray screening. Among the most significant improvements over the classical radiography belong generation of the screen from very arbitrary angle and interactive rotation of the image in real-time. In order to obtain the most realistic final image, we put the emphasis on the accurate simulation of physical properties of the x-ray radiation. We also try to get as low computational time needed to gain one image as possible. For this purpose we present a parallelization model that decomposes the required work of some components into several processors' cores and thus noticeably decreases the running time of the algorithm.
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