Search results for "intersection"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
30	Noam Zeilberger	Refinement types and computational duality.	PLPV	2009	DBLP DOI BibTeX RDF	duality, effects, intersection types, focusing, union types
30	Reasey Praing, Markus Schneider 0001	Efficient Implementation Techniques for Topological Predicates on Complex Spatial Objects.	GeoInformatica	2008	DBLP DOI BibTeX RDF	complex spatial object, predicate verification, predicate determination, topological feature vector, exploration phase, evaluation phase, nine-intersection matrix characterization, matrix thinning, minimum cost decision tree, spatial database, topological predicate
30	Jana Dunfield	Refined typechecking with Stardust.	PLPV	2007	DBLP DOI BibTeX RDF	type refinements, dependent types, intersection types, union types
30	Yingpeng Sang, Hong Shen 0001, Yasuo Tan, Naixue Xiong	Efficient Protocols for Privacy Preserving Matching Against Distributed Datasets.	ICICS	2006	DBLP DOI BibTeX RDF	set matching, distributed database, cryptographic protocol, privacy preservation, set intersection
30	Ryuhei Uehara, Yushi Uno	Laminar Structure of Ptolemaic Graphs and Its Applications.	ISAAC	2005	DBLP DOI BibTeX RDF	algorithmic graph theory, intersection model, ptolemaic graphs, data structure, Hamiltonian cycle
30	Dinesh Manocha, James Demmel	Algorithms for intersecting parametric and algebraic curves I: simple intersections.	ACM Trans. Graph.	1994	DBLP DOI BibTeX RDF	robustness, eigenvalues, algebraic, curves, intersection, parametric, resultants
28	Dana Dachman-Soled, Tal Malkin, Mariana Raykova 0001, Moti Yung	Efficient Robust Private Set Intersection.	ACNS	2009	DBLP DOI BibTeX RDF	Cryptographic Protocols, Privacy Preserving Data Mining, Secure Two-party Computation, Set Intersection
28	Frank Schmitt, Lutz Priese	Vanishing Point Detection with an Intersection Point Neighborhood.	DGCI	2009	DBLP DOI BibTeX RDF	measurable lines, Image analysis, vanishing points, intersection points
28	Dominic A. P. Greenwood, Branislav Burdiliak, Ivan Trencanský, Hartmut Armbruster, Christian Dannegger	GreenWave distributed traffic intersection control.	AAMAS (2)	2009	DBLP BibTeX RDF	distributed multiagent traffic intersection phase control, emergent green wave, video camera sensor
28	Daniel Andres, Viktor Levandovskyy, Jorge Martín-Morales	Principal intersection and bernstein-sato polynomial of an affine variety.	ISSAC	2009	DBLP DOI BibTeX RDF	bernstein-sato polynomial of variety, initial ideal, intersection with subalgebra, non-commutative gr?bner bases, preimage of ideal, annihilator, d-modules
28	Yingpeng Sang, Hong Shen 0001	Privacy preserving set intersection based on bilinear groups.	ACSC	2008	DBLP BibTeX RDF	non interactive zero-knowledge proof, cryptographic protocol, privacy preservation, set intersection, bilinear groups
28	Toufiq Benbouziane, Hassan El Houari, M'hammed El Kahoui	Polynomial parametrization of nonsingular complete intersection curves.	Appl. Algebra Eng. Commun. Comput.	2007	DBLP DOI BibTeX RDF	Complete intersection, Locally nilpotent derivation, Polynomial parametrization
28	Dariusz Kusmierek	The Inhabitation Problem for Rank Two Intersection Types.	TLCA	2007	DBLP DOI BibTeX RDF	type inhabitation problem, lambda calculus, intersection types, alternating Turing machine
28	Dario Andrea Bini, Ana Marco	Computing curve intersection by means of simultaneous iterations.	Numer. Algorithms	2006	DBLP DOI BibTeX RDF	curve intersection, structured matrices, Sylvester resultant, simultaneous iterations, numerical algorithms
28	Boris Aronov, Mark de Berg, Chris Gray	Ray shooting and intersection searching amidst fat convex polyhedra in 3-space.	SCG	2006	DBLP DOI BibTeX RDF	computational geometry, ray shooting, fat objects, intersection searching
28	Viktor Levandovskyy	Intersection of ideals with non-commutative subalgebras.	ISSAC	2006	DBLP DOI BibTeX RDF	homomorphism of algebras, intersection with subalgebra, non-commutative algebra, preimage of ideal, restriction, elimination, Groebner bases
28	Ziba Eslami, Gholamreza B. Khosrovshahi, Morteza Mohammad Noori	Enumeration of t-Designs Through Intersection Matrices.	Des. Codes Cryptogr.	2004	DBLP DOI BibTeX RDF	derived designs, intersection matrices, t-designs
28	Jinyuan Jia, Kai Tang 0001, Ajay Joneja	Biconic subdivision of surfaces of revolution and its applications in intersection problems.	Vis. Comput.	2004	DBLP DOI BibTeX RDF	Quadric decomposition, Bi-conic arc fitting, Revolute quadrics, Intersection, Surfaces of revolution
28	Guido Stehr, Helmut E. Graeb, Kurt Antreich	Performance trade-off analysis of analog circuits by normal-boundary intersection.	DAC	2003	DBLP DOI BibTeX RDF	normal-boundary intersection, performance space exploration, topology selection, analog circuits, Pareto optimality, trade-off analysis
28	Xiao-Shan Gao, Christoph M. Hoffmann, Wei-Qiang Yang	Solving spatial basic geometric constraint configurations with locus intersection.	Symposium on Solid Modeling and Applications	2002	DBLP DOI BibTeX RDF	locus intersection, parametric CAD, spatial basic configuration, geometric constraint solving
28	Ulrich Schmid 0001, Klaus Schossmaier	How to reconcile fault-tolerant interval intersection with the Lipschitz condition.	Distributed Comput.	2001	DBLP DOI BibTeX RDF	Fault-tolerant interval intersection, Marzullo function, Interval-based clock synchronization, Hybrid fault models
28	Shin-Ting Wu, Osmar Aléssio, Sueli I. Rodrigues Costa	On Estimating Local Geometric Properties of Intersection Curves.	SIBGRAPI	2000	DBLP DOI BibTeX RDF	local geometric property estimation, torsion vectors, curvature vectors, binormal vectors, tangent vectors, normal vectors, marching directions, computational geometry, robust algorithm, intersection curves
28	Neil C. Rowe	Absolute Bounds on Set Intersection and Union Sizes from Distribution Information.	IEEE Trans. Software Eng.	1988	DBLP DOI BibTeX RDF	union sizes, distribution information, closed-form bounds, rule-based system architecture, statistical analysis, statistical analysis, database theory, set theory, set theory, Boolean algebra, Boolean algebra, file organisation, file organisation, set intersection, database access
28	Piotr Hoffman	Unions of Equational Monadic Theories.	RTA	2006	DBLP DOI BibTeX RDF
28	Shihong Du, Qiao Wang, Qiming Qin, Yipeng Yang	Fuzzy Description of Topological Relations II: Computation Methods and Examples.	ICNC (3)	2005	DBLP DOI BibTeX RDF
28	Anders Adamson, Marc Alexa, Andrew Nealen	Adaptive sampling of intersectable models exploiting image and object-space coherence.	SI3D	2005	DBLP DOI BibTeX RDF	object-space coherence, adaptive sampling
28	Farzin Mokhtarian, Sadegh Abbasi	Matching shapes with self-intersections: application to leaf classification.	IEEE Trans. Image Process.	2004	DBLP DOI BibTeX RDF
28	Joon-Kyung Seong, Ku-Jin Kim, Myung-Soo Kim, Gershon Elber	Intersecting a Freeform Surface with a Ruled or a Ringed Surface.	GMP	2004	DBLP DOI BibTeX RDF
28	Graham D. Finlayson, Gerald Schaefer	Convex and Non-convex Illuminant Constraints for Dichromatic Colour Constancy.	CVPR (1)	2001	DBLP DOI BibTeX RDF
28	Masatake Higashi, Hisashi Nakano, Atsuhide Nakamura, Mamoru Hosaka	Use of topological constraints in construction and processing of robust solid models.	Symposium on Solid Modeling and Applications	2001	DBLP DOI BibTeX RDF	face-based representation, robust computation, computer-aided design, solid modeling, feature modeling, topological constraint
28	Rida T. Farouki, C. Andrew Neff, M. A. O'Conner	Automatic parsing of degenerate quadric-surface intersections.	ACM Trans. Graph.	1989	DBLP DOI BibTeX RDF
26	Erich Hartmann	The normalform of a space curve and its application to surface design.	Vis. Comput.	2001	DBLP DOI BibTeX RDF	normalform, constant distance sum/product surfaces, pipe surfaces, G n, isophotes, blending, bisectors, intersection points, intersection curves
26	Jeroen Schillewaert, Joseph A. Thas	Characterizations of Hermitian varieties by intersection numbers.	Des. Codes Cryptogr.	2009	DBLP DOI BibTeX RDF	51A45, 51A50, 05B25, 51E12, AMS Classifications 51E20
26	Anna T. Lawniczak, Bruno N. Di Stefano	Development of Road Traffic CA Model of 4-Way Intersection to Study Travel Time.	Complex (2)	2009	DBLP DOI BibTeX RDF	Travel Time, Cellular Automata, Traffic Modeling, Agent Based Simulation
26	Aljona Zorina, David E. Avison	Innovation Management in the Knowledge Economy: The Intersection of Macro and Micro Levels.	WSKS (1)	2009	DBLP DOI BibTeX RDF	strategic programs, government, knowledge society, innovation management
26	Giorgio Donati, Nicola Durante	On the intersection of two subgeometries of PG ( n , q ).	Des. Codes Cryptogr.	2008	DBLP DOI BibTeX RDF	05B25, AMS Classifications 51E20
26	Mariangiola Dezani-Ciancaglini, Roberto Di Cosmo, Elio Giovannetti, Makoto Tatsuta	On Isomorphisms of Intersection Types.	CSL	2008	DBLP DOI BibTeX RDF
26	Kevin T. Phelps, Mercè Villanueva	Intersection of Hadamard Codes.	IEEE Trans. Inf. Theory	2007	DBLP DOI BibTeX RDF
26	Stefan Göller, Markus Lohrey, Carsten Lutz	PDL with Intersection and Converse Is 2 EXP-Complete.	FoSSaCS	2007	DBLP DOI BibTeX RDF
26	Sotiris E. Nikoletseas, Christoforos L. Raptopoulos, Paul G. Spirakis	Expander Properties and the Cover Time of Random Intersection Graphs.	MFCS	2007	DBLP DOI BibTeX RDF
26	Benjamin Hoffmann, Yury Lifshits, Dirk Nowotka	Maximal Intersection Queries in Randomized Graph Models.	CSR	2007	DBLP DOI BibTeX RDF
26	Flora Dilys Salim, Seng Wai Loke, Andry Rakotonirainy, Shonali Krishnaswamy	U&I Aware: A Framework Using Data Mining and Collision Detection to Increase Awareness for Intersection Users.	AINA Workshops (2)	2007	DBLP DOI BibTeX RDF
26	Jan Kratochvíl, Martin Pergel	Geometric Intersection Graphs: Do Short Cycles Help?	COCOON	2007	DBLP DOI BibTeX RDF
26	Cornelia Dangelmayr, Stefan Felsner	Chordal Graphs as Intersection Graphs of Pseudosegments.	GD	2006	DBLP DOI BibTeX RDF
26	Erhard Godehardt, Jerzy Jaworski, Katarzyna Rybarczyk	Random Intersection Graphs and Classification.	GfKl	2006	DBLP DOI BibTeX RDF
26	Puspita Deo, Heather J. Ruskin	Simulation of Heterogeneous Motorised Traffic at a Signalised Intersection.	ACRI	2006	DBLP DOI BibTeX RDF	motorised traffic, two-component cellular automata, Heterogeneous
26	Kai-Tai Song, Jen-Chao Tai	Image-based turn ratio measurement at road intersection.	ICIP (1)	2005	DBLP DOI BibTeX RDF
26	Ferruccio Damiani	Rank-2 Intersection and Polymorphic Recursion.	TLCA	2005	DBLP DOI BibTeX RDF
26	Shihong Du, Qiming Qin, Qiao Wang, Bin Li 0061	Fuzzy Description of Topological Relations I: A Unified Fuzzy 9-Intersection Model.	ICNC (3)	2005	DBLP DOI BibTeX RDF
26	Min Tang 0001, Jinxiang Dong	Simulated Annealing Genetic Algorithm for Surface Intersection.	ICNC (3)	2005	DBLP DOI BibTeX RDF
26	Stefan Böttcher, Rita Steinmetz	Embedding XML Schema Constraints in Search-Based Intersection Tests for XPath Query Optimization.	DEXA Workshops	2005	DBLP DOI BibTeX RDF
26	Xin Yao 0003, Changshui Zhang, Jinwen Chen, Yanda Li	On the Scale-Free Intersection Graphs.	ICCSA (2)	2005	DBLP DOI BibTeX RDF
26	David Eppstein	Testing bipartiteness of geometric intersection graphs.	SODA	2004	DBLP BibTeX RDF
26	Pankaj K. Agarwal, Mark H. Overmars, Micha Sharir	Computing maximally separated sets in the plane and independent sets in the intersection graph of unit disks.	SODA	2004	DBLP BibTeX RDF
26	Sébastien Carlier, Jeff Polakow, J. B. Wells, A. J. Kfoury	System E: Expansion Variables for Flexible Typing with Linear and Non-linear Types and Intersection Types.	ESOP	2004	DBLP DOI BibTeX RDF
26	Hiromi Kawatsu, Sadao Takaba, Kuniaki Souma	Proposal and Evaluation of a System Which Aims Reduction in Unexpected Collision at Non-signal Intersection.	AsiaSim	2004	DBLP DOI BibTeX RDF
26	Akemi Gálvez, Jaime Puig-Pey, Andrés Iglesias 0001	A Differential Method for Parametric Surface Intersection.	ICCSA (2)	2004	DBLP DOI BibTeX RDF
26	Pankaj K. Agarwal, Nabil H. Mustafa	Independent Set of Intersection Graphs of Convex Objects in 2D.	SWAT	2004	DBLP DOI BibTeX RDF
26	Vladlen Koltun	Segment Intersection Searching Problems in General Settings.	Discret. Comput. Geom.	2003	DBLP DOI BibTeX RDF
26	Jan Kratochvíl, Martin Pergel	Two Results on Intersection Graphs of Polygons.	GD	2003	DBLP DOI BibTeX RDF
26	Jaime Puig-Pey, Akemi Gálvez, Andrés Iglesias 0001	A New Differential Approach for Parametric-Implicit Surface Intersection.	International Conference on Computational Science	2003	DBLP DOI BibTeX RDF
26	Steven M. Robbins, Sue Whitesides	On the Reliability of Triangle Intersection in 3D.	ICCSA (3)	2003	DBLP DOI BibTeX RDF
26	Christoph Ambühl, Uli Wagner 0001	On the Clique Problem in Intersection Graphs of Ellipses.	ISAAC	2002	DBLP DOI BibTeX RDF
26	Jaume Martí-Farré, Carles Padró	Secret Sharing Schemes on Access Structures with Intersection Number Equal to One.	SCN	2002	DBLP DOI BibTeX RDF	ideal schemes, Cryptography, secret sharing schemes, information rate
26	Vladlen Koltun	Segment intersection searching problems in general settings.	SCG	2001	DBLP DOI BibTeX RDF
26	Taneli Mielikäinen, Esko Ukkonen	The Complexity of Maximum Matroid-Greedoid Intersection.	FCT	2001	DBLP DOI BibTeX RDF
26	Jakub Cerný, Daniel Král, Helena Nyklová, Ondrej Pangrác	On Intersection Graphs of Segments with Prescribed Slopes.	GD	2001	DBLP DOI BibTeX RDF
26	Allyn Dimock, Ian Westmacott, Robert Muller, Franklyn A. Turbak, J. B. Wells, Jeffrey Considine	Program Representation Size in an Intermediate Language with Intersection and Union Types.	Types in Compilation	2000	DBLP DOI BibTeX RDF
26	V. S. Anil Kumar 0001, Sunil Arya, H. Ramesh	Hardness of Set Cover with Intersection 1.	ICALP	2000	DBLP DOI BibTeX RDF
26	K. A. Al-shalfan, Stanley S. Ipson, J. G. B. Haigh	Distinguishing Real and Virtual Edge Intersection in Pairs of Uncalibrated Images.	IDEAL	2000	DBLP DOI BibTeX RDF	pattern recognition, stereo matching, intersections, image rectification
26	Sébastien Fourey, Rémy Malgouyres	Intersection Number of Paths Lying on a Digital Surface and a New Jordan Theorem.	DGCI	1999	DBLP DOI BibTeX RDF	surfels curves, Digital topology, digital surfaces
26	Adriana B. Compagnoni	Decidability of Higher-Order Subtyping with Intersection Types.	CSL	1994	DBLP DOI BibTeX RDF
26	Shreesh Jadhav, Asish Mukhopadhyay, Binay K. Bhattacharya	An Optimal Algorithm for the Intersection Radius of a Set of Convex Polygons.	FSTTCS	1992	DBLP DOI BibTeX RDF
26	Catriel Beeri, Michael Kifer	A theory of intersection anomalies in relational database schemes.	J. ACM	1987	DBLP DOI BibTeX RDF
26	Catriel Beeri, Michael Kifer	Elimination of intersection anomalies from database schemes.	J. ACM	1986	DBLP DOI BibTeX RDF
26	Christian Bouville	Bounding ellipsoids for ray-fractal intersection.	SIGGRAPH	1985	DBLP DOI BibTeX RDF
26	Catriel Beeri, Michael Kifer	Elimination of Intersection Anomalies from Database Schemes.	PODS	1983	DBLP DOI BibTeX RDF
24	Masato Koyamaishi, Yasuhiro Suzuki, Mitsuhiro Wada, Tomohiro Endo, Toshiaki Fujii, Masayuki Tanimoto	Visual assistant system "HIR" for Safe Driving at an Intersection -Interlligent Intersection-.	ICDE Workshops	2005	DBLP DOI BibTeX RDF
24	Yao-Yi Chiang, Craig A. Knoblock, Cyrus Shahabi, Ching-Chien Chen	Automatic and Accurate Extraction of Road Intersections from Raster Maps.	GeoInformatica	2009	DBLP DOI BibTeX RDF	raster map, road layer, road intersection, geospatial data integration, fusion, vector data, conflation, imagery
24	James B. Orlin	A Fast, Simpler Algorithm for the Matroid Parity Problem.	IPCO	2008	DBLP DOI BibTeX RDF	Matroid parity, matroid matching, matroid intersection, nonbipartite matching
24	Art Tevs, Ivo Ihrke, Hans-Peter Seidel	Maximum mipmaps for fast, accurate, and scalable dynamic height field rendering.	SI3D	2008	DBLP DOI BibTeX RDF	height field intersection, simplification/level of detail, surface details, texturing techniques, GPU, graphics hardware, real-time rendering, displacement mapping, spatial data structures
24	Adarsh Krishnamurthy, Rahul Khardekar, Sara McMains, Kirk Haller, Gershon Elber	Performing efficient NURBS modeling operations on the GPU.	Symposium on Solid and Physical Modeling	2008	DBLP DOI BibTeX RDF	interactive trimming, inverse evaluation, GPU, sketching, NURBS, prefix sum, intersection curves
24	Hans Raj Tiwary	On the hardness of minkowski addition and related operations.	SCG	2007	DBLP DOI BibTeX RDF	coNP-hardness, extended convex hull, polytope intersection, computational geometry, polytopes, turing reduction, minkowski addition
24	Bing Liu 0004, Maoyuan Yu, Dennis Maier, Reinhard Männer	An Efficient and Accurate Method for 3D-Point Reconstruction from Multiple Views.	Int. J. Comput. Vis.	2005	DBLP DOI BibTeX RDF	3D-point reconstruction, resection, first-order approximation, maximum likelihood estimation, intersection, bundle adjustment, structure estimate
24	Markus Schneider 0001, Thomas Behr	Topological Relationships Between Complex Lines and Complex Regions.	ER	2005	DBLP DOI BibTeX RDF	topological constraint rule, proof-by-constraint-and-drawing, complex spatial data type, 9-intersection model, Topological predicate
24	Sylvain Lazard, Luis Mariano Peñaranda, Sylvain Petitjean	Intersecting quadrics: an efficient and exact implementation.	SCG	2004	DBLP DOI BibTeX RDF	C++ implementation, intersection of quadrics, experimental analysis
24	Jens Gravesen, Michael Ungstrup	Constructing Invariant Fairness Measures for Surfaces.	Adv. Comput. Math.	2002	DBLP DOI BibTeX RDF	fairness measure, plane intersection, fairing, invariants, surface design
24	Peter D. Lauren, N. Nandhakumar	Recovering the viewing parameters of random, translated and noisy projections of asymmetric objects.	CVPR	1996	DBLP DOI BibTeX RDF	noisy projections, translated projections, randomly acquired projections, asymmetric objects, common lines algorithm, three-dimensional Fourier space, translational displacement, in vivo images, underwater scenes, radioastronomy, geoseismic analysis, portable radiography, industrial inspection, image reconstruction, Fourier transforms, Fourier transforms, intersection, cells, random projections, viruses, three-dimensional reconstruction, molecules
24	Nir Katzir, Michael Lindenbaum, Moshe Porat	Curve Segmentation Under Partial Occlusion.	IEEE Trans. Pattern Anal. Mach. Intell.	1994	DBLP DOI BibTeX RDF	2-D shape boundary segmentation, partially occluded object recognition, smooth boundary curve, similarity transformation invariance, intersection point existence conditions, image segmentation, transforms, image recognition, gray level images, partial occlusion, curve segmentation
24	Lori L. Pollock, Mary Lou Soffa	An Incremental Version of Iterative Data Flow Analysis.	IEEE Trans. Software Eng.	1989	DBLP DOI BibTeX RDF	union data flow problems, incremental version, iterative data flow analysis, intersection data-flow problems, program edits, data-flow information, data-flow sets, two-phase approach, data-flow sets, local code changes, parallel programming, systems analysis, iterative methods, set theory, iterative approach
23	Frank Dévai, László Neumann	A Rectangle-Intersection Algorithm with Limited Resource Requirements.	CIT	2010	DBLP DOI BibTeX RDF	power-efficient software, bounding rectangles, intersection reporting, optimal algorithm, 3D graphics
23	Fatemeh Nourani, Mohammad Ali Jabraeil Jamali	Improved Circles Intersection Algorithm for Localization in Wireless Sensor Networks.	SNPD	2010	DBLP DOI BibTeX RDF	Improved Circles Intersection, wireless sensor networks, Localization
23	Xiao-Fan Zhi, Zhi-Cheng Liao, Yi Sun	An Intersection-Centric IBF* Algorithm for Traffic Simulation Routing Guidance.	NCM	2009	DBLP DOI BibTeX RDF	intersection-centric, algorithm, routing guidance
23	Yiyan Wang, Yuexian Zou, Hang Shi, He Zhao	Video Image Vehicle Detection System for Signaled Traffic Intersection.	HIS (1)	2009	DBLP DOI BibTeX RDF	vehicle detection system, intersection, video image
23	Srecko Brlek, Michel Koskas, Xavier Provençal	A Linear Time and Space Algorithm for Detecting Path Intersection.	DGCI	2009	DBLP DOI BibTeX RDF	Freeman code, lattice paths, radix tree, discrete figures, data structure, self-intersection
23	Shirish Tatikonda, Flavio Junqueira, Berkant Barla Cambazoglu, Vassilis Plachouras	On efficient posting list intersection with multicore processors.	SIGIR	2009	DBLP DOI BibTeX RDF	list intersection, multicores, parallel query processing
23	Alain Frisch, Giuseppe Castagna, Véronique Benzaken	Semantic subtyping: Dealing set-theoretically with function, union, intersection, and negation types.	J. ACM	2008	DBLP DOI BibTeX RDF	negation types, Subtyping, higher-order functions, intersection types, union types
23	Mariangiola Dezani-Ciancaglini, Furio Honsell, Fabio Alessi	A complete characterization of complete intersection-type preorders.	ACM Trans. Comput. Log.	2003	DBLP DOI BibTeX RDF	lambda models, completeness, Lambda calculus, intersection types
23	Haim Kaplan, Eyal Molad, Robert Endre Tarjan	Dynamic rectangular intersection with priorities.	STOC	2003	DBLP DOI BibTeX RDF	rectangular intersection, rectangular point location, packet classification, orthogonal range searching
23	Wael M. Badawy, Walid G. Aref	On Local Heuristics to Speed Up Polygon-Polygon Intersection Tests.	ACM-GIS	1999	DBLP DOI BibTeX RDF	polygon-polygon intersection, query processing, spatial databases