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**1 - 2**of**2**### Column Oriented Compilation of Variant Tables

"... Abstract. The objective of this work is to improve variant table evaluation in a configurator by compiling/compressing the tables individually to reduce both processing time and space. The main result is a proposed simple heuristic for decomposing the variant table into subtables and a representati ..."

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Abstract. The objective of this work is to improve variant table evaluation in a configurator by compiling/compressing the tables individually to reduce both processing time and space. The main result is a proposed simple heuristic for decomposing the variant table into subtables and a representation linking these subtables in a directed acyclic graph (DAG). The size of the compression obtained by this heuristic for examples used in [2, 10] is comparable to that achieved there. However, a formal analysis of complexity has not yet been completed. A prototype implemented in Java exists. Objectives in designing it were to keep it completely decoupled from any particular configurator, while using little machinery in order to keep software maintenance costs low. Testing both on abstract examples and on tables that resemble real customer data is ongoing and looks promising. Non-atomic table cells (such as real intervals, or value sets) are supported. My approach to negative variant tables

### A COMPARATIVE STUDY OF GENERALIZED ARC-CONSISTENCY ALGORITHMS

, 2014

"... In this thesis, we study several algorithms for enforcing Generalized Arc-Consistency (GAC), which is the most popular consistency property for solving Constraint Satis-faction Problems (CSPs) with backtrack search. The popularity of such algorithms stems from their relative low cost and effectivene ..."

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In this thesis, we study several algorithms for enforcing Generalized Arc-Consistency (GAC), which is the most popular consistency property for solving Constraint Satis-faction Problems (CSPs) with backtrack search. The popularity of such algorithms stems from their relative low cost and effectiveness in improving the performance of search. Virtually all commercial and public-domain constraint solvers include some implementation of a generic GAC algorithm. In recent years, several algorithms for enforcing GAC have been proposed in the literature that rely on increasingly complex data structures and mechanisms to improve performance. In this thesis, we study, assess, and compare a basic algorithm for generic constraints (i.e, GAC2001), new algorithms for table constraints (i.e., STR1, STR2, STR3, eSTR1, eSTR2, and STR-Ni), and an algorithm for constraints expressed as multi-valued decision diagram (i.e., mddc). We explain the mechanisms of the above algorithms, and empirically evalu-ate and compare their performances. We propose a new hybrid algorithm that uses a selection criterion to combine the use of STR1 and STR-Ni.