Search results for "Labeling"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
98	Lei Zhang 0011, Yan Tong, Qiang Ji	Active Image Labeling and Its Application to Facial Action Labeling.	ECCV (2)	2008	DBLP DOI BibTeX RDF
90	Amos Korman	General compact labeling schemes for dynamic trees.	Distributed Comput.	2007	DBLP DOI BibTeX RDF	Distributed algorithms, Dynamic networks, Labeling schemes, Routing schemes
83	Zhixi Fang, Xiaobo Li 0001	A parallel processing approach to image object labeling problems (abstract only).	ACM Conference on Computer Science	1987	DBLP DOI BibTeX RDF
77	Kesheng Wu, Ekow J. Otoo, Kenji Suzuki 0001	Optimizing two-pass connected-component labeling algorithms.	Pattern Anal. Appl.	2009	DBLP DOI BibTeX RDF	Union-find algorithm, Optimization, Decision tree, Equivalence relation, Connected-component labeling
77	Liang Xu, Tok Wang Ling, Huayu Wu 0001, Zhifeng Bao	DDE: from dewey to a fully dynamic XML labeling scheme.	SIGMOD Conference	2009	DBLP DOI BibTeX RDF	dewey, dynamic xml, update, labeling scheme
74	Victor S. Sheng, Foster J. Provost, Panagiotis G. Ipeirotis	Get another label? improving data quality and data mining using multiple, noisy labelers.	KDD	2008	DBLP DOI BibTeX RDF	data preprocessing, data selection
71	Radim Baca, Michal Krátký	TJDewey - On the Efficient Path Labeling Scheme Holistic Approach.	DASFAA Workshops	2009	DBLP DOI BibTeX RDF	twig pattern query, holistic algorithms, path labeling scheme, TJFast, XML
66	Juan Xu, Zhanhuai Li, Yanlong Wang, Rugui Yao	An Efficient Encoding and Labeling Scheme for Dynamic XML Data.	DEXA	2007	DBLP DOI BibTeX RDF	Forbidden Code Segment (FCS), re-labeling, updates, labeling scheme, Lexicographical Order
65	Jun-Ki Min, Jihyun Lee, Chin-Wan Chung	An Efficient Encoding and Labeling for Dynamic XML Data.	DASFAA	2007	DBLP DOI BibTeX RDF	Dynamic XML, Labeling and Update
59	Zhuowei Bao, Susan B. Davidson, Sanjeev Khanna, Sudeepa Roy	An optimal labeling scheme for workflow provenance using skeleton labels.	SIGMOD Conference	2010	DBLP DOI BibTeX RDF	workflow, provenance, labeling, reachability
59	Markus Muhr, Roman Kern, Michael Granitzer	Analysis of structural relationships for hierarchical cluster labeling.	SIGIR	2010	DBLP DOI BibTeX RDF	statistical methods, structural information, topic hierarchies, cluster labeling
59	Reuven Cohen, Pierre Fraigniaud, David Ilcinkas, Amos Korman, David Peleg	Labeling Schemes for Tree Representation.	Algorithmica	2009	DBLP DOI BibTeX RDF	Spanning tree, Labeling scheme, Tree representation
59	Yang Yang 0059, Bin B. Zhu, Rui Guo, Linjun Yang, Shipeng Li 0001, Nenghai Yu	A comprehensive human computation framework: with application to image labeling.	ACM Multimedia	2008	DBLP DOI BibTeX RDF	common sense problems, humansense, human computation, distributed knowledge acquisition, image labeling
59	Wen Wu, Jie Yang 0001	SmartLabel: an object labeling tool using iterated harmonic energy minimization.	ACM Multimedia	2006	DBLP DOI BibTeX RDF	gaussian random field, harmonic energy minimization, object labeling, semi-supervised learning
59	Changqing Li, Tok Wang Ling	QED: a novel quaternary encoding to completely avoid re-labeling in XML updates.	CIKM	2005	DBLP DOI BibTeX RDF	dynamic XML, quaternary, update, labeling scheme
59	Hans L. Bodlaender, Hajo Broersma, Fedor V. Fomin, Artem V. Pyatkin, Gerhard J. Woeginger	Radio Labeling with Pre-assigned Frequencies.	ESA	2002	DBLP DOI BibTeX RDF	Radio labeling, k-colorling, computational complexity, approximation algorithm, graph algorithms, frequency assignment, cograph
58	Lei Zhang 0011, Yan Tong, Qiang Ji	Interactive labeling of facial action units.	ICPR	2008	DBLP DOI BibTeX RDF
58	Hao-Jen Kao, Chun-Cheng Lin, Hsu-Chun Yen	Many-to-one boundary labeling.	APVIS	2007	DBLP DOI BibTeX RDF
58	Amos Korman, David Peleg, Yoav Rodeh	Constructing Labeling Schemes Through Universal Matrices.	ISAAC	2006	DBLP DOI BibTeX RDF
58	Joseph Naor	From Balanced Graph Partitioning to Balanced Metric Labeling.	ESA	2005	DBLP DOI BibTeX RDF
58	Gabriele Neyer	Map Labeling with Application to Graph Drawing.	Drawing Graphs	1999	DBLP DOI BibTeX RDF
57	Pierre Fraigniaud, Amos Korman	On randomized representations of graphs using short labels.	SPAA	2009	DBLP DOI BibTeX RDF	adjacency labeling schemes, ancestry labeling schemes, probabilistic embeddings, universal graphs, distributed algorithms
53	U. L. Jau, Chee Siong Teh	Real-Time Object-Based Video Segmentation Using Colour Segmentation and Connected Component Labeling.	IVIC	2009	DBLP DOI BibTeX RDF	Connected component labeling (CCL), real-time colour video image, object-based video segmentation application, region labeling
53	Tiziana Calamoneri, Saverio Caminiti, Stephan Olariu, Rossella Petreschi	On the L(h, k)-Labeling of Co-comparability Graphs.	ESCAPE	2007	DBLP DOI BibTeX RDF	L(h and k)-Labeling, co-comparability graphs, unit-interval graphs, interval graphs
53	Hagit Attiya, Hadas Shachnai, Tami Tamir	Local Labeling and Resource Allocation Using Preprocessing.	WDAG	1994	DBLP DOI BibTeX RDF	locality, resource allocation, response time, orientation, labeling, preprocessing
52	Ramadhana Bramandia, Byron Choi, Wee Keong Ng	On incremental maintenance of 2-hop labeling of graphs.	WWW	2008	DBLP DOI BibTeX RDF	2-hop, incremental maintenance, graph indexing, reachability test
52	Sankaranarayanan Ananthakrishnan, Shrikanth S. Narayanan	Fine-grained pitch accent and boundary tone labeling with parametric F0 features.	ICASSP	2008	DBLP DOI BibTeX RDF
52	Amos Korman	General Compact Labeling Schemes for Dynamic Trees.	DISC	2005	DBLP DOI BibTeX RDF
52	Amos Korman, David Peleg, Yoav Rodeh	Labeling Schemes for Dynamic Tree Networks.	Theory Comput. Syst.	2004	DBLP DOI BibTeX RDF
52	So-Hee Park, Mi-Young Park, Yong-Kee Jun	A Comparison of Scalable Labeling Schemes for Detecting Races in OpenMP Programs.	WOMPAT	2001	DBLP DOI BibTeX RDF
52	David Peleg	Proximity-Preserving Labeling Schemes and Their Applications.	WG	1999	DBLP DOI BibTeX RDF
52	Gunnar W. Klau, Petra Mutzel	Combining Graph Labeling and Compaction.	GD	1999	DBLP DOI BibTeX RDF
50	Afef Kacem, Abdel Belaïd, Mohamed Ben Ahmed	Automatic extraction of printed mathematical formulas using fuzzy logic and propagation of context.	Int. J. Document Anal. Recognit.	2001	DBLP DOI BibTeX RDF	Mathematic formula extraction, Symbol labeling, Context propagation, Fuzzy logic, Document segmentation
49	Jean-Daniel Fekete, Catherine Plaisant	Excentric Labeling: Dynamic Neighborhood Labeling for Data Visualization.	CHI	1999	DBLP DOI BibTeX RDF	dynamic labeling, visualization, evaluation, label
49	Martin Luboschik, Heidrun Schumann, Hilko Cords	Particle-based labeling: Fast point-feature labeling without obscuring other visual features.	IEEE Trans. Vis. Comput. Graph.	2008	DBLP DOI BibTeX RDF
47	Xinhua Zhuang, Robert M. Haralick, Hyonam Joo	A Simplex-Like Algorithm for the Relaxation Labeling Process.	IEEE Trans. Pattern Anal. Mach. Intell.	1989	DBLP DOI BibTeX RDF	simplex-like algorithm, relaxation labeling process, fast convergence property, one-more-step theorem, consistent-labeling search space, pattern recognition, linear programming, linear programming, variational inequality, convergence of numerical methods, relaxation theory
46	David Carmel, Haggai Roitman, Naama Zwerdling	Enhancing cluster labeling using wikipedia.	SIGIR	2009	DBLP DOI BibTeX RDF	wikipedia, cluster labeling
46	György J. Simon, Vipin Kumar 0001, Zhi-Li Zhang	Semi-supervised approach to rapid and reliable labeling of large data sets.	KDD	2008	DBLP DOI BibTeX RDF	labeling data sets, semi-supervised learning, performance guarantees
46	Haibin Cheng, Ruofei Zhang, Yefei Peng, Jianchang Mao, Pang-Ning Tan	Maximum Margin Active Learning for Sequence Labeling with Different Length.	ICDM	2008	DBLP DOI BibTeX RDF	Struct Support Vector Machine, Sequence Labeling, Subphrase Generation, Natural Language Processing, Uncertainty, Active Learning
46	Qiaozhu Mei, Xuehua Shen, ChengXiang Zhai	Automatic labeling of multinomial topic models.	KDD	2007	DBLP DOI BibTeX RDF	topic model labeling, multinomial distribution, statistical topic models
46	Ken Been, Eli Daiches, Chee-Keng Yap	Dynamic Map Labeling.	IEEE Trans. Vis. Comput. Graph.	2006	DBLP DOI BibTeX RDF	label selection, label filtering, label consistency, computational cartography, HCI, GIS, human-computer interface, preprocessing, realtime, dynamic maps, Map labeling, label placement
46	Jun Zhu 0001, Zaiqing Nie, Ji-Rong Wen, Bo Zhang 0010, Wei-Ying Ma	Simultaneous record detection and attribute labeling in web data extraction.	KDD	2006	DBLP DOI BibTeX RDF	attribute labeling, data record detection, hierarchical conditional random fields, conditional random fields, web page segmentation
46	Jun Yang 0003, Rong Yan, Alexander G. Hauptmann	Multiple instance learning for labeling faces in broadcasting news video.	ACM Multimedia	2005	DBLP DOI BibTeX RDF	face labeling, machine learning, multiple instance learning, news video
46	Chun-Cheng Lin, Hsiang-Yun Wu, Hsu-Chun Yen	Boundary Labeling in Text Annotation.	IV	2009	DBLP DOI BibTeX RDF
46	Pinar Donmez, Jaime G. Carbonell, Jeff G. Schneider	Efficiently learning the accuracy of labeling sources for selective sampling.	KDD	2009	DBLP DOI BibTeX RDF	labeler selection, noisy labelers, active learning, estimation
46	Don J. Torrieri, Matthew C. Valenti	Constellation labeling maps for low error floors.	IEEE Trans. Wirel. Commun.	2008	DBLP DOI BibTeX RDF
46	Yuval Rabani, Leonard J. Schulman, Chaitanya Swamy	Approximation algorithms for labeling hierarchical taxonomies.	SODA	2008	DBLP BibTeX RDF
46	Jirí Fiala 0001, Petr A. Golovach, Jan Kratochvíl	Computational Complexity of the Distance Constrained Labeling Problem for Trees (Extended Abstract).	ICALP (1)	2008	DBLP DOI BibTeX RDF
46	Jason J. Corso, Alan L. Yuille, Zhuowen Tu	Graph-shifts: Natural image labeling by dynamic hierarchical computing.	CVPR	2008	DBLP DOI BibTeX RDF
46	Christian Wojek, Bernt Schiele	A Dynamic Conditional Random Field Model for Joint Labeling of Object and Scene Classes.	ECCV (4)	2008	DBLP DOI BibTeX RDF
46	Haixun Wang, Hao He 0006, Jun Yang 0001, Philip S. Yu, Jeffrey Xu Yu	Dual Labeling: Answering Graph Reachability Queries in Constant Time.	ICDE	2006	DBLP DOI BibTeX RDF
46	Changqing Li, Tok Wang Ling, Min Hu	Reuse or Never Reuse the Deleted Labels in XML Query Processing Based on Labeling Schemes.	DASFAA	2006	DBLP DOI BibTeX RDF
46	Xiaodong Wu, Mong-Li Lee, Wynne Hsu	A Prime Number Labeling Scheme for Dynamic Ordered XML Trees.	ICDE	2004	DBLP DOI BibTeX RDF
46	Mauritsius Tuga, Mirka Miller	Delta-Optimum Exclusive Sum Labeling of Certain Graphs with Radius One.	IJCCGGT	2003	DBLP DOI BibTeX RDF
46	Amos Korman, David Peleg	Labeling Schemes for Weighted Dynamic Trees.	ICALP	2003	DBLP DOI BibTeX RDF
44	Ying-Da Chen, Jing-Ho Yan	A study on cyclic bandwidth sum.	J. Comb. Optim.	2007	DBLP DOI BibTeX RDF	Proper labeling, Cyclic bandwidth sum, Complete bipartite graph, Cyclic displacement, Zero cycle, Extended labeling, Balanced 2-color, Tree
44	Tiziana Calamoneri, Saverio Caminiti, Rossella Petreschi	A General Approach to L ( h, k )-Label Interconnection Networks.	J. Comput. Sci. Technol.	2008	DBLP DOI BibTeX RDF	L(h, k)-labeling, multistage interconnection network, channel assignment problem
43	Pierre Fraigniaud	Provenance for database transformations.	ICDT	2010	DBLP DOI BibTeX RDF
40	Wan D. Bae, Shayma Alkobaisi, Petr Vojtechovský, Sada Narayanappa, Kye Y. Bae	Convex onion peeling genetic algorithm: an efficient solution to map labeling of point-feature.	SAC	2010	DBLP DOI BibTeX RDF	automated map labeling, onion peeling, genetic algorithm, GIS, cartography
40	Amos Korman, David Peleg	Compact separator decompositions in dynamic trees and applications to labeling schemes.	Distributed Comput.	2008	DBLP DOI BibTeX RDF	Informative labeling schemes, Distributed algorithms, Dynamic networks, Graph decompositions, Routing schemes
40	Haakon Ringberg, Augustin Soule, Jennifer Rexford	WebClass: adding rigor to manual labeling of traffic anomalies.	Comput. Commun. Rev.	2008	DBLP DOI BibTeX RDF	database, data sharing, network traffic analysis, data labeling
40	Ken Been, Martin Nöllenburg, Sheung-Hung Poon, Alexander Wolff 0001	Optimizing active ranges for consistent dynamic map labeling.	SCG	2008	DBLP DOI BibTeX RDF	dynamic map labeling, approximation algorithms, np-hardness
40	Dong Chan An, Seog Park	Access Control Labeling Scheme for Efficient Secure XML Query Processing.	KES (2)	2008	DBLP DOI BibTeX RDF	XML, Access Control, Labeling Scheme
40	Dong Chan An, So Mi Park, Seog Park	Efficient Secure Labeling Method under Dynamic XML Data Streams.	IWSEC	2008	DBLP DOI BibTeX RDF	Labeling Method, Dynamic XML, Access Control, Query Processing, Data streams
40	Toru Hasunuma, Toshimasa Ishii, Hirotaka Ono 0001, Yushi Uno	An Algorithm for L(2, 1)-Labeling of Trees.	SWAT	2008	DBLP DOI BibTeX RDF	frequency/channel assignment, L(2 and 1)-labeling, graph algorithm, vertex coloring
40	Amos Korman	Labeling Schemes for Vertex Connectivity.	ICALP	2007	DBLP DOI BibTeX RDF	Graph algorithms, labeling schemes, vertex-connectivity
40	Amos Korman, David Peleg	Compact Separator Decompositions in Dynamic Trees and Applications to Labeling Schemes.	DISC	2007	DBLP DOI BibTeX RDF	informative labeling schemes, Distributed algorithms, dynamic networks, graph decompositions, routing schemes
40	Lifeng He, Yuyan Chao, Kenji Suzuki 0001	A Run-Based Two-Scan Labeling Algorithm.	ICIAR	2007	DBLP DOI BibTeX RDF	label equivalence, run data, pattern recognition, connected components, linear-time algorithm, Labeling algorithm
40	Binhai Zhu, Minghui Jiang 0001	A combinatorial theorem on labeling squares with points and its application.	J. Comb. Optim.	2006	DBLP DOI BibTeX RDF	Square packing, Combinatorics, Map labeling
40	Changqing Li, Tok Wang Ling, Jiaheng Lu, Tian Yu	On reducing redundancy and improving efficiency of XML labeling schemes.	CIKM	2005	DBLP DOI BibTeX RDF	XML, redundancy, query, labeling scheme
40	Keke Chen, Ling Liu 0001	ClusterMap: labeling clusters in large datasets via visualization.	CIKM	2004	DBLP DOI BibTeX RDF	cluster visualization, human factors in clustering, data clustering, cluster labeling
40	Cyril Gavoille, Christophe Paul	Optimal Distance Labeling for Interval and Circular-Arc Graphs.	ESA	2003	DBLP DOI BibTeX RDF	distance queries, Data-structure, interval graphs, labeling scheme, circular-arc graphs
40	Sylvain Jaume, Benoît Macq, Simon K. Warfield	Labeling the Brain Surface Using a Deformable Multiresolution Mesh.	MICCAI (1)	2002	DBLP DOI BibTeX RDF	cortex labeling, cortical surface, sulci and gyri, brain segmentation, progressive mesh, brain atlas, multiresolution mesh
40	Cyril Gavoille, Michal Katz, Nir A. Katz, Christophe Paul, David Peleg	Approximate Distance Labeling Schemes.	ESA	2001	DBLP DOI BibTeX RDF	Local representations, approximate distance, distributed data structures, labeling schemes
40	Qing X. Wu	A Correlation-Relaxation-Labeling Framework for Computing Optical Flow - Template Matching from a New Perspective.	IEEE Trans. Pattern Anal. Mach. Intell.	1995	DBLP DOI BibTeX RDF	cloud motion fields, motion estimation, Optical flow, template matching, cross-correlation, relaxation labeling, dynamic scene analysis
40	Pierre Parent, Steven W. Zucker	Radial Projection: An Efficient Update Rule for Relaxation Labeling.	IEEE Trans. Pattern Anal. Mach. Intell.	1989	DBLP DOI BibTeX RDF	radial projection, pattern recognition, pattern recognition, graph theory, picture processing, picture processing, graphs, convergence, iterative methods, contextual information, convergence of numerical methods, relaxation labeling, update rule
40	Hsi-Ho Liu, Tzay Y. Young, Amitava Das	A Multilevel Parallel Processing Approach to Scene Labeling Problems.	IEEE Trans. Pattern Anal. Mach. Intell.	1988	DBLP DOI BibTeX RDF	multilevel parallel processing, scene labeling, parallel tree search, multilevel array architectures, parallel processing, computerised picture processing, computerised picture processing, computerised pattern recognition, computerised pattern recognition, polynomial, trees (mathematics)
40	Toru Hasunuma, Toshimasa Ishii, Hirotaka Ono 0001, Yushi Uno	A Linear Time Algorithm for L(2, 1)-Labeling of Trees.	ESA	2009	DBLP DOI BibTeX RDF
40	Jiang Su, Jelber Sayyad-Shirabad, Stan Matwin, Jin Huang	Active Learning with Automatic Soft Labeling for Induction of Decision Trees.	Canadian AI	2009	DBLP DOI BibTeX RDF
40	Yasuaki Ito, Koji Nakano	Component labeling for k-concave binary images using an FPGA.	IPDPS	2008	DBLP DOI BibTeX RDF
40	Yasuaki Ito, Koji Nakano	Optimized Component Labeling Algorithm for Using in Medium Sized FPGAs.	PDCAT	2008	DBLP DOI BibTeX RDF
40	Liang Xu, Zhifeng Bao, Tok Wang Ling	A Dynamic Labeling Scheme Using Vectors.	DEXA	2007	DBLP DOI BibTeX RDF
40	Brandon Mikulis, Raghuveer M. Rao	Object Labeling for 3-D Cross-Sectional Data using Trajectory Tracking.	ICIP	2006	DBLP DOI BibTeX RDF
40	Gang Wu, Kuo Zhang, Can Liu, Juan-Zi Li	Adapting Prime Number Labeling Scheme for Directed Acyclic Graphs.	DASFAA	2006	DBLP DOI BibTeX RDF
40	Tiziana Calamoneri, Emanuele G. Fusco, Richard B. Tan, Paola Vocca	L(h, 1, 1)-Labeling of Outerplanar Graphs.	SIROCCO	2006	DBLP DOI BibTeX RDF
40	Michael A. Bekos, Michael Kaufmann 0001, Katerina Potika, Antonios Symvonis	Multi-stack Boundary Labeling Problems.	FSTTCS	2006	DBLP DOI BibTeX RDF
40	Jiefeng Cheng, Jeffrey Xu Yu, Xuemin Lin 0001, Haixun Wang, Philip S. Yu	Fast Computation of Reachability Labeling for Large Graphs.	EDBT	2006	DBLP DOI BibTeX RDF
40	Lei Chen 0003, Zheng Huang, Raghu Ramakrishnan 0001	Cost-Based Labeling of Groups of Mass Spectra.	SIGMOD Conference	2004	DBLP DOI BibTeX RDF
40	David Peleg	Informative Labeling Schemes for Graphs.	MFCS	2000	DBLP DOI BibTeX RDF
40	Frank Wagner 0001, Alexander Wolff 0001	A Combinatorial Framework for Map Labeling.	GD	1998	DBLP DOI BibTeX RDF
38	Shuyi Zheng, Matthew R. Scott, Ruihua Song, Ji-Rong Wen	Pictor: an interactive system for importing data from a website.	KDD	2008	DBLP DOI BibTeX RDF	Pictor, labeling cost, wrapper assisted labeling, information extraction, wrapper
38	Amos Korman, Shay Kutten	Distributed verification of minimum spanning trees.	PODC	2006	DBLP DOI BibTeX RDF	graph property verification, proof labeling, distributed algorithms, self stabilization, minimum spanning tree, labeling schemes, network algorithms
38	Keke Chen, Ling Liu 0001	iVIBRATE: Interactive visualization-based framework for clustering large datasets.	ACM Trans. Inf. Syst.	2006	DBLP DOI BibTeX RDF	Clustering, performance, labeling, interactive visualization, large datasets
38	Tiziana Calamoneri	Exact Solution of a Class of Frequency Assignment Problems in Cellular Networks.	ICTCS	2003	DBLP DOI BibTeX RDF	L(h,k)-labeling, multihop radio networks, cellular graphs, frequency assignment problem
38	Louis J. Billera, Gábor Hetyei	Decompositions of Partially Ordered Sets.	Order	2000	DBLP DOI BibTeX RDF	Cohen-Macaulay, EL-labeling, flag, flag f-vector, leveled planar, lexicographically shellable, shellable, lattice, planar, partially ordered set, chain
38	Sook-Yeon Kim, Kyung-Yong Chwa	Optimal embeddings of multiple graphs into a hypermesh.	ICPADS	1997	DBLP DOI BibTeX RDF	optimal embeddings, multiple graphs, hypermesh, versatile parallel architecture, 2-dimensional mesh, linear connection, hyper-edge, labeling strategy, optimal expansion, N-node graph, hypercube, hypercube networks, congestion, torus, dilation
37	Changqing Li, Tok Wang Ling, Min Hu	Efficient updates in dynamic XML data: from binary string to quaternary string.	VLDB J.	2008	DBLP DOI BibTeX RDF
37	Jirí Fiala 0001, Petr A. Golovach, Jan Kratochvíl	Distance Constrained Labelings of Trees.	TAMC	2008	DBLP DOI BibTeX RDF
37	Kensaku Mori, Sinya Ema, Takayuki Kitasaka, Yoshito Mekada, Ichiro Ide, Hiroshi Murase, Yasuhito Suenaga, Hirotsugu Takabatake, Masaki Mori, Hiroshi Natori	Automated Nomenclature of Bronchial Branches Extracted from CT Images and Its Application to Biopsy Path Planning in Virtual Bronchoscopy.	MICCAI (2)	2005	DBLP DOI BibTeX RDF
37	Eran Borenstein, Shimon Ullman	Learning to Segment.	ECCV (3)	2004	DBLP DOI BibTeX RDF