Annual Report 2004-2005
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Object Oriented Programming
No. 52 March-A pril'1990 $3.95 T H E M TEe H CAL J 0 URN A L COPIA Object Oriented Programming First it was BASIC, then it was structures, now it's objects. C++ afi<;ionados feel, of course, that objects are so powerful, so encompassing that anything could be so defined. I hope they're not placing bets, because if they are, money's no object. C++ 2.0 page 8 An objective view of the newest C++. Training A Neural Network Now that you have a neural network what do you do with it? Part two of a fascinating series. Debugging C page 21 Pointers Using MEM Keep C fro111 (C)rashing your system. An AT Keyboard Interface Use an AT keyboard with your latest project. And More ... Understanding Logic Families EPROM Programming Speeding Up Your AT Keyboard ((CHAOS MADE TO ORDER~ Explore the Magnificent and Infinite World of Fractals with FRAC LS™ AN ELECTRONIC KALEIDOSCOPE OF NATURES GEOMETRYTM With FracTools, you can modify and play with any of the included images, or easily create new ones by marking a region in an existing image or entering the coordinates directly. Filter out areas of the display, change colors in any area, and animate the fractal to create gorgeous and mesmerizing images. Special effects include Strobe, Kaleidoscope, Stained Glass, Horizontal, Vertical and Diagonal Panning, and Mouse Movies. The most spectacular application is the creation of self-running Slide Shows. Include any PCX file from any of the popular "paint" programs. FracTools also includes a Slide Show Programming Language, to bring a higher degree of control to your shows. -
Computability of Fraïssé Limits
COMPUTABILITY OF FRA¨ISSE´ LIMITS BARBARA F. CSIMA, VALENTINA S. HARIZANOV, RUSSELL MILLER, AND ANTONIO MONTALBAN´ Abstract. Fra¨ıss´estudied countable structures S through analysis of the age of S, i.e., the set of all finitely generated substructures of S. We investigate the effectiveness of his analysis, considering effectively presented lists of finitely generated structures and asking when such a list is the age of a computable structure. We focus particularly on the Fra¨ıss´elimit. We also show that degree spectra of relations on a sufficiently nice Fra¨ıss´elimit are always upward closed unless the relation is definable by a quantifier-free formula. We give some sufficient or necessary conditions for a Fra¨ıss´elimit to be spectrally universal. As an application, we prove that the computable atomless Boolean algebra is spectrally universal. Contents 1. Introduction1 1.1. Classical results about Fra¨ıss´elimits and background definitions4 2. Computable Ages5 3. Computable Fra¨ıss´elimits8 3.1. Computable properties of Fra¨ıss´elimits8 3.2. Existence of computable Fra¨ıss´elimits9 4. Examples 15 5. Upward closure of degree spectra of relations 18 6. Necessary conditions for spectral universality 20 6.1. Local finiteness 20 6.2. Finite realizability 21 7. A sufficient condition for spectral universality 22 7.1. The countable atomless Boolean algebra 23 References 24 1. Introduction Computable model theory studies the algorithmic complexity of countable structures, of their isomorphisms, and of relations on such structures. Since algorithmic properties often depend on data presentation, in computable model theory classically isomorphic structures can have different computability-theoretic properties. -
A Computational Basis for Conic Arcs and Boolean Operations on Conic Polygons
A Computational Basis for Conic Arcs and Boolean Operations on Conic Polygons Eric Berberich, Arno Eigenwillig, Michael Hemmer Susan Hert, Kurt Mehlhorn, and Elmar Schomer¨ [eric|arno|hemmer|hert|mehlhorn|schoemer]@mpi-sb.mpg.de Max-Planck-Institut fur¨ Informatik, Stuhlsatzenhausweg 85 66123 Saarbruck¨ en, Germany Abstract. We give an exact geometry kernel for conic arcs, algorithms for ex- act computation with low-degree algebraic numbers, and an algorithm for com- puting the arrangement of conic arcs that immediately leads to a realization of regularized boolean operations on conic polygons. A conic polygon, or polygon for short, is anything that can be obtained from linear or conic halfspaces (= the set of points where a linear or quadratic function is non-negative) by regularized boolean operations. The algorithm and its implementation are complete (they can handle all cases), exact (they give the mathematically correct result), and efficient (they can handle inputs with several hundred primitives). 1 Introduction We give an exact geometry kernel for conic arcs, algorithms for exact computation with low-degree algebraic numbers, and a sweep-line algorithm for computing arrangements of curved arcs that immediately leads to a realization of regularized boolean operations on conic polygons. A conic polygon, or polygon for short, is anything that can be ob- tained from linear or conic halfspaces (= the set of points where a linear or quadratic function is non-negative) by regularized boolean operations (Figure 1). A regularized boolean operation is a standard boolean operation (union, intersection, complement) followed by regularization. Regularization replaces a set by the closure of its interior and eliminates dangling low-dimensional features. -