Search results for "authorities"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
84	Guido Boella, Leendert W. N. van der Torre	Institutions with a hierarchy of authorities in distributed dynamic environments.	Artif. Intell. Law	2008	DBLP DOI BibTeX RDF	Institutions, Permissions, Normative systems
59	Ronny Lempel, Shlomo Moran	SALSA: the stochastic approach for link-structure analysis.	ACM Trans. Inf. Syst.	2001	DBLP DOI BibTeX RDF	TKC effect, WEB, random walks, SALSA, Link-structure analysis, hubs and authorities
56	Jingjing Wu, Jiwu Jing, Jingqiang Lin	A Decentralized Certification Authority Based on Real World Trust Relationships.	CSSE (3)	2008	DBLP DOI BibTeX RDF
50	Kenneth G. Paterson, Sriramkrishnan Srinivasan	Security and Anonymity of Identity-Based Encryption with Multiple Trusted Authorities.	Pairing	2008	DBLP DOI BibTeX RDF	multi-TA IBE, multiple trusted authorities, anonymity, identity-based encryption
47	Stephen S. Yau, Yin Yin	A Privacy Preserving Repository for Data Integration across Data Sharing Services.	IEEE Trans. Serv. Comput.	2008	DBLP DOI BibTeX RDF
47	Li Zhou, Yong Zhang 0002, Chun-Xiao Xing	A Collaborative Filtering Algorithm Based on Global and Domain Authorities.	ICADL	2008	DBLP DOI BibTeX RDF	Global Authority, Domain Authority, Collaboration Filtering
47	François Fouss, Marco Saerens, Jean-Michel Renders	Links Between Kleinberg's Hubs and Authorities, Correspondence Analysis, and Markov Chains.	ICDM	2003	DBLP DOI BibTeX RDF
40	Allan Borodin, Gareth O. Roberts, Jeffrey S. Rosenthal, Panayiotis Tsaparas	Finding authorities and hubs from link structures on the World Wide Web.	WWW	2001	DBLP DOI BibTeX RDF	Kleinberg's algorithm, web searching, authorities, link analysis, threshold, Bayesian, hubs, SALSA
37	Melissa Chase, Sherman S. M. Chow	Improving privacy and security in multi-authority attribute-based encryption.	CCS	2009	DBLP DOI BibTeX RDF	multi-authority, removing trusted party, privacy, attribute based encryption, anonymous credential
37	Luis Carlos Coronado García, Carlos Hernández-López, Carlos Pérez Leguízamo	Autonomous Decentralized Root Certification Authority System.	ICDCS Workshops	2009	DBLP DOI BibTeX RDF
37	Mitsuhiro Mabuchi, Yasushi Shinjo, Akira Sato, Kazuhiko Kato	An Access Control Model for Web-Services That Supports Delegation and Creation of Authority.	ICN	2008	DBLP DOI BibTeX RDF	Web-Service, Access Control, Capability
37	Ronald Cramer, Rosario Gennaro, Berry Schoenmakers	A Secure and Optimally Efficient Multi-Authority Election Scheme.	EUROCRYPT	1997	DBLP DOI BibTeX RDF
37	Liqun Chen 0002, Keith Harrison, David Soldera, Nigel P. Smart	Applications of Multiple Trust Authorities in Pairing Based Cryptosystems.	InfraSec	2002	DBLP DOI BibTeX RDF
37	Fatima Haouari, Tamer Elsayed	Are authorities denying or supporting? Detecting stance of authorities towards rumors in Twitter.	Soc. Netw. Anal. Min.	2023	DBLP DOI BibTeX RDF
31	Kenneth G. Paterson, Sriramkrishnan Srinivasan	Building Key-Private Public-Key Encryption Schemes.	ACISP	2009	DBLP DOI BibTeX RDF	multiple trusted authorities, TA anonymity, standard model, public-key encryption, identity-based encryption, key-privacy
31	Nacim Fateh Chikhi, Bernard Rothenburger, Nathalie Aussenac-Gilles	A New Algorithm for Community Identification in Linked Data.	KES (1)	2008	DBLP DOI BibTeX RDF	authoritative documents, VHITS, PHITS, authorities, HITS, web communities, hubs, community identification, community mining
31	Oren Kurland, Lillian Lee	PageRank without hyperlinks: structural re-ranking using links induced by language models.	SIGIR	2005	DBLP DOI BibTeX RDF	graph-based retrieval, structural re-ranking, social networks, authorities, language modeling, PageRank, HITS, hubs, high-accuracy retrieval
31	Hung-Yu Kao, Ming-Syan Chen, Shian-Hua Lin, Jan-Ming Ho	Entropy-based link analysis for mining web informative structures.	CIKM	2002	DBLP DOI BibTeX RDF	information extraction, entropy, link analysis, anchor text, informative structure, hubs and authorities
31	Javier López 0001, Antonio Mana, José A. Montenegro, Juan J. Ortega, José M. Troya	Towards a Trustful and Flexible Environment for Secure Communications with Public Administrations.	EGOV	2002	DBLP DOI BibTeX RDF	Electronic Forms, Public Key Infrastructure, Public Administrations, Secure Communications, Certification Authorities
31	Gerhard Jakisch	E-Signature versus E-Identity the Creation of the Digital Citizen.	DEXA Workshops	2000	DBLP DOI BibTeX RDF	e-Signature, e-Identity, digital citizen, e-address, email address, technical solution, administrative requirements, administrative processes, advanced electronic signature, e-commerce, e-Government, government data processing, holistic approach, public authorities
31	Vishwa Prasad, Sreenivasa Potakamuri, Michael Ahern, Igor Balabine, Michah Lerner, Partha Dutta	Scalable Policy Driven and General Purpose Public Key Infrastructure (PKI).	ACSAC	2000	DBLP DOI BibTeX RDF	interoperable security infrastructure, AT? Labs, multiple certificate authorities, third-party CA systems, uniform enrollment procedures, Verisign, authenticated IP services, policy descriptions, certificate sources, X.509v3 certificates, CRML, PKCS, X509, XML, software architecture, authentication, public key cryptography, certification, client-server systems, public key infrastructure, revocation, intranets, message authentication, CRL, OCSP, middleware platform
31	Neil C. Audsley, I. J. Bate, Alan Burns 0001	Putting fixed priority scheduling theory into engineering practice for safety critical applications.	IEEE Real Time Technology and Applications Symposium	1996	DBLP DOI BibTeX RDF	aircraft computers, engineering practice, industrial safety-critical hard real-time systems, class A systems, civil aircraft software standard DO178B, evidence gathering, technical benefits, evidence presentation, scheduling, real-time systems, timing, certification, safety-critical software, fixed-priority scheduling, aerospace computing, certification authorities, software standards, timing requirements
28	Loukas Dimitriou, Antony Stathopoulos	Optimal Co-evolutionary Strategies for the Competitive Maritime Network Design Problem.	EvoWorkshops	2009	DBLP DOI BibTeX RDF	Freight Networks, Maritime Container Terminal Systems, Competitive Network Design, Co-Evolutionary non-Cooperative Algorithms
28	Dusko Pavlovic	Dynamics, Robustness and Fragility of Trust.	Formal Aspects in Security and Trust	2008	DBLP DOI BibTeX RDF
28	Ee-Peng Lim, Ba-Quy Vuong, Hady Wirawan Lauw, Aixin Sun	Measuring Qualities of Articles Contributed by Online Communities.	Web Intelligence	2006	DBLP DOI BibTeX RDF
28	Changjie Wang, Dickson K. W. Chiu, Ho-fung Leung	Anonymity and Security in Public Internet Forums.	CEC	2005	DBLP DOI BibTeX RDF
28	Efthimios Tambouris	An Integrated Platform for Tele-voting and Tele-consulting within and across European Cities: The EURO-CITI Project.	EGOV	2002	DBLP DOI BibTeX RDF
28	Eleni Panopoulou, Efthimios Tambouris, Maria Zotou, Konstantinos A. Tarabanis	Evaluating eParticipation Sophistication of Regional Authorities Websites: The Case of Greece and Spain.	ePart	2009	DBLP DOI BibTeX RDF	Spain, regional authority, eParticipation, Greece, website evaluation
28	Elina Eriksson, Jan Gulliksen, Åsa Cajander	Introducing usability roles in public authorities.	NordiCHI	2008	DBLP DOI BibTeX RDF	usability expert, usability professional, case study, public authority
28	Jitka Komarkova, Martin Novak, Renata Bilkova, Ondrej Visek, Zdenek Valenta	Usability of GeoWeb Sites: Case Study of Czech Regional Authorities Web Sites.	BIS	2007	DBLP DOI BibTeX RDF	GeoWeb, Internet GIS, Usability, Usability Testing
28	David W. Chadwick	Authorisation Using Attributes from Multiple Authorities.	WETICE	2006	DBLP DOI BibTeX RDF
28	Jun Furukawa 0001, Shoko Yonezawa	Group Signatures with Separate and Distributed Authorities.	SCN	2004	DBLP DOI BibTeX RDF
28	Radu Jurca, Boi Faltings	"CONFESS". Eliciting Honest Feedback Without Independent Verification Authorities.	AMEC	2004	DBLP DOI BibTeX RDF
28	Nicholas J. Adams, Simon Haston, Nat Gillespie, Ann Macintosh	Conventional and Electronic Service Delivery within Public Authorities: The Issues and Lessons from the Private Sector.	EGOV	2003	DBLP DOI BibTeX RDF
28	Paul-Alexandru Chirita, Daniel Olmedilla, Wolfgang Nejdl	Finding Related Hubs and Authorities.	LA-WEB	2003	DBLP DOI BibTeX RDF	Hubrank, hub.nder, web search, PageRank
28	Apollònia Martínez Nadal, Josep Lluís Ferrer-Gomila	Liability of Certification Authorities: A Juridical Point of View.	ISC	2001	DBLP DOI BibTeX RDF
28	George V. Meghabghab	Discovering Authorities and Hubs in Different Topological Web Graph Structures.	ITCC	2001	DBLP DOI BibTeX RDF
22	Amitabha Bagchi, Garima Lahoti	Relating web pages to enable information-gathering tasks.	Hypertext	2009	DBLP DOI BibTeX RDF	related pages, authorities, similarity measures, network flow, information gathering, hubs
22	Gregory Piatetsky-Shapiro	Interview with Jon Kleinberg.	SIGKDD Explor.	2007	DBLP DOI BibTeX RDF	authorities, social network analysis, links, small-world
22	Oren Kurland, Lillian Lee	Respect my authority!: HITS without hyperlinks, utilizing cluster-based language models.	SIGIR	2006	DBLP DOI BibTeX RDF	graph-based retrieval, structural re-ranking, clusters, authorities, language modeling, bipartite graph, HITS, hubs, cluster-based language models, high-accuracy retrieval
22	Tsung Teng Chen, Liang Qi Xie	Identifying Critical Focuses in Research Domains.	IV	2005	DBLP DOI BibTeX RDF	research focuses, visualization, graph theory, authorities, citation analysis, hubs
22	Hua Yan, Phil Richards	Enhanced searching algorithms for relevant web pages using hyperlink graphs.	ACM Southeast Regional Conference (1)	2005	DBLP DOI BibTeX RDF	authorities, similarity measure, link analysis, HITS, hubs
22	Hung-Yu Kao, Shian-Hua Lin, Jan-Ming Ho, Ming-Syan Chen	Mining Web Informative Structures and Contents Based on Entropy Analysis.	IEEE Trans. Knowl. Data Eng.	2004	DBLP DOI BibTeX RDF	information extraction, entropy, link analysis, anchor text, Informative structure, hubs and authorities
22	Brian D. Davison 0001	Toward a unification of text and link analysis.	SIGIR	2003	DBLP DOI BibTeX RDF	RageRank, knowledge representation, search engines, authorities, link analysis, eigenvectors, HITS, hubs
22	Ronny Lempel, Aya Soffer	PicASHOW: pictorial authority search by hyperlinks on the web.	ACM Trans. Inf. Syst.	2002	DBLP DOI BibTeX RDF	image hubs, Image retrieval, link structure analysis, hubs and authorities
22	Krishna Bharat, George A. Mihaila	When experts agree: using non-affiliated experts to rank popular topics.	ACM Trans. Inf. Syst.	2002	DBLP DOI BibTeX RDF	host affiliation, topic experts, ranking, authorities, connectivity, link analysis, WWW search
22	David W. Chadwick, Carmen Carroll, S. Harvey, John P. New, Andrew J. Young	Experiences of Using a Public Key Infrastructure to Access Patient Confidential Data over the Internet.	HICSS	2002	DBLP DOI BibTeX RDF	medical telematics, security, Internet, WWW, usability, digital signatures, encryption, Public key infrastructures, user acceptance, ease of use, certification authorities, validation testing
22	Arvind Arasu, Junghoo Cho, Hector Garcia-Molina, Andreas Paepcke, Sriram Raghavan	Searching the Web.	ACM Trans. Internet Techn.	2001	DBLP DOI BibTeX RDF	information retrieval, indexing, search engine, authorities, link analysis, PageRank, crawling, HITS
22	Ronny Lempel, Aya Soffer	PicASHOW: pictorial authority search by hyperlinks on the Web.	WWW	2001	DBLP DOI BibTeX RDF	image hubs, image retrieval, link structure analysis, hubs and authorities
19	Xiaohong Cui	The Logic of Knowledge-Based Cooperation in the Social Dilemma.	LORI	2009	DBLP DOI BibTeX RDF
19	Darren Minifie, Yvonne Coady	Getting mobile with mobile devices: using the web to improve transit accessibility.	W4A	2009	DBLP DOI BibTeX RDF	mobile devices, accessibility, mobile web, public transportation
19	Karin Berkhoff, Sylvia Herrmann	Modeling Land Use Change: A GIS Based Modeling Framework to Support Integrated Land Use Planning (NabanFrame).	AGILE Conf.	2009	DBLP DOI BibTeX RDF
19	Nixon Muganda	Assessing alignment of an e-government project in the context of a developing country: a Heideggerian perspective.	SAICSIT	2009	DBLP DOI BibTeX RDF	Kenya, technocracy, e-government, hospitality, drifting, actor-network
19	Benoît Libert, Damien Vergnaud	Towards Black-Box Accountable Authority IBE with Short Ciphertexts and Private Keys.	Public Key Cryptography	2009	DBLP DOI BibTeX RDF	efficiency, traceability, Identity-based encryption
19	Alberto Jiménez Rozo	Supply of accounting and financial information entities in charge of control surveillance: a proposal for the streamlining of procedures.	ICEGOV	2009	DBLP DOI BibTeX RDF	customer-server, enterprise resources and software planning (ERP), government to business (G2B), internet data center (IDC), partnerships management and directors, remote surveillance/intervention, confidentiality, software as a service (SaaS), internal control
19	Ralf Küsters, Tomasz Truderung, Andreas Vogt 0001	Improving and Simplifying a Variant of Prêt à Voter.	VoteID	2009	DBLP DOI BibTeX RDF
19	Aly Abdel Fattah, Janaka Y. Ruwanpura	An integrated CAD and simulation model for concrete operations.	WSC	2008	DBLP DOI BibTeX RDF
19	Huang Lin, Zhenfu Cao, Xiaohui Liang, Jun Shao	Secure Threshold Multi Authority Attribute Based Encryption without a Central Authority.	INDOCRYPT	2008	DBLP DOI BibTeX RDF	Threshold Multi Authority ABE, Without a central authority
19	Dennis Y. W. Liu, Joseph K. Liu, Yi Mu 0001, Willy Susilo, Duncan S. Wong	Revocable Ring Signature.	J. Comput. Sci. Technol.	2007	DBLP DOI BibTeX RDF	anonymity, group signature, revocability, ring signature
19	Franco Frattolillo	Watermarking Protocol for Web Context.	IEEE Trans. Inf. Forensics Secur.	2007	DBLP DOI BibTeX RDF
19	Yutaka Oiwa, Kazukuni Kobara, Hajime Watanabe	A New Variant for an Attack Against RSA Signature Verification Using Parameter Field.	EuroPKI	2007	DBLP DOI BibTeX RDF	List of Keywords vulnerability, certificate verification, attacks
19	Melissa Chase	Multi-authority Attribute Based Encryption.	TCC	2007	DBLP DOI BibTeX RDF
19	Mayumi Itakura Kamata, Ai Yoshimoto Yoshida, Hisashi Yoshida, Nao Aoki	Figure Out the Current Software Requirements Engineering - What Practitioners Expect to Requirements Engineering? -.	APSEC	2007	DBLP DOI BibTeX RDF
19	Ashish Kumar Singh, Priya Chandran	A Secure and Efficient Multi-authority Proactive Election Scheme.	ICISS	2007	DBLP DOI BibTeX RDF
19	Adam J. Lee, Kazuhiro Minami, Marianne Winslett	Lightweight cnsistency enforcement schemes for distributed proofs with hidden subtrees.	SACMAT	2007	DBLP DOI BibTeX RDF	distributed proving, pervasive computing, consistency
19	Siddharth Kaza, Daning Hu, Homa Atabakhsh, Hsinchun Chen	Predicting criminal relationships using multivariate survival analysis.	DG.O	2007	DBLP BibTeX RDF	criminal networks, social network analysis, intelligence and security informatics
19	Marianne Azer, Sherif El-Kassas, Magdy S. El-Soudani	Certification and Revocation Schemes in Ad Hoc Networks Survey and Challenges.	ICSNC	2007	DBLP DOI BibTeX RDF
19	Siddharth Kaza, Daning Hu, Hsinchun Chen	Dynamic Social Network Analysis of a Dark Network: Identifying Significant Facilitators.	ISI	2007	DBLP DOI BibTeX RDF
19	Jing Jin, Gail-Joon Ahn, Mohamed Shehab, Hongxin Hu	Towards trust-aware access management for ad-hoc collaborations.	CollaborateCom	2007	DBLP DOI BibTeX RDF
19	Jens Groth, Rafail Ostrovsky	Cryptography in the Multi-string Model.	CRYPTO	2007	DBLP DOI BibTeX RDF	Common random string model, multi-string model, universally composable commitment, multi-party computation, non-interactive zero-knowledge
19	Konstantinos P. Anagnostopoulos, Athanasios P. Vavatsikos	An AHP model for construction contractor prequalification.	Oper. Res.	2006	DBLP DOI BibTeX RDF	Bid evaluation, Contractor selection, Prequalification, AHP, Multicriteria analysis
19	Philippe Golle	A Private Stable Matching Algorithm.	Financial Cryptography	2006	DBLP DOI BibTeX RDF
19	Tomoyuki Yamada	Logical Dynamics of Commands and Obligations.	JSAI	2006	DBLP DOI BibTeX RDF
19	Pinar Yolum, Munindar P. Singh	Engineering self-organizing referral networks for trustworthy service selection.	IEEE Trans. Syst. Man Cybern. Part A	2005	DBLP DOI BibTeX RDF
19	Sherman S. M. Chow, Richard W. C. Lui, Lucas Chi Kwong Hui, Siu-Ming Yiu	Identity Based Delegation Network.	Mycrypt	2005	DBLP DOI BibTeX RDF	Delegation network, bilinear pairings, proxy signature, identity-based cryptography, batch verification
19	Jayson E. Rome, Robert M. Haralick	Towards a Formal Concept Analysis Approach to Exploring Communities on the World Wide Web.	ICFCA	2005	DBLP DOI BibTeX RDF
19	Sudhir Agarwal 0001, Barbara Sprick	Specification of Access Control and Certification Policies for Semantic Web Services.	EC-Web	2005	DBLP DOI BibTeX RDF
19	Zheng Guo, Tohru Okuyama, Marion R. Finley Jr.	A New Trust Model for PKI Interoperability.	ICAS/ICNS	2005	DBLP DOI BibTeX RDF	Certification Authority (CA), Gateway Certification Authority (GWCA), PKI Interoperability, Public Key Infrastructure (PKI), X.509, Certification Paths
19	Albert Levi, M. Ufuk Çaglayan, Çetin Kaya Koç	Use of nested certificates for efficient, dynamic, and trust preserving public key infrastructure.	ACM Trans. Inf. Syst. Secur.	2004	DBLP DOI BibTeX RDF	nested certificates, key management, public key infrastructure, Digital certificates
19	Jens Groth	Efficient Maximal Privacy in Boardroom Voting and Anonymous Broadcast.	Financial Cryptography	2004	DBLP DOI BibTeX RDF
19	Thomas Müllner, Dominik G. Grimm	Applications and Interfaces for e-Government.	EGOV	2004	DBLP DOI BibTeX RDF
19	Lin Chen 0020, Xiaoqin Huang, Jinyuan You	Certificate-Based Authentication and Authorization Architecture in Digital Library.	ICADL	2004	DBLP DOI BibTeX RDF
19	Zoran Despotovic, Jean-Claude Usunier, Karl Aberer	Towards Peer-To-Peer Double Auctioning.	HICSS	2004	DBLP DOI BibTeX RDF
19	Srdjan Capkun, Levente Buttyán, Jean-Pierre Hubaux	Self-Organized Public-Key Management for Mobile Ad Hoc Networks.	IEEE Trans. Mob. Comput.	2003	DBLP DOI BibTeX RDF	security, Mobile ad hoc networks, self-organization, public-key cryptography, PGP, key authentication
19	Marcel Hoogwout	Super Pilots, Subsidizing or Self-Organization: Stimulating e-Government Initiatives in Dutch Local Governments.	EGOV	2003	DBLP DOI BibTeX RDF
19	Roberta Morici, Eugenio Nunziata, Gloria Sciarra	A Knowledge Management System for E-government Projects and Actors.	KMGov	2003	DBLP DOI BibTeX RDF
19	Dongwan Shin, Gail-Joon Ahn, Sangrae Cho, Seunghun Jin	On modeling system-centric information for role engineering.	SACMAT	2003	DBLP DOI BibTeX RDF	attributive permissions, role-based access control, information flow, information model, role engineering
19	David W. Chadwick, Darren P. Mundy	Policy Based Electronic Transmission of Prescriptions.	POLICY	2003	DBLP DOI BibTeX RDF
19	Jan A. M. Wiegerinck	Introduction to the risk based design of safety instrumented systems for the process industry.	ICARCV	2002	DBLP DOI BibTeX RDF
19	Cheun Ngen Chong, René van Buuren, Pieter H. Hartel, Geert Kleinhuis	Security Attributes Based Digital Rights Management.	IDMS/PROMS	2002	DBLP DOI BibTeX RDF
19	Liqun Chen 0002, Keith Harrison, Andrew Moss, David Soldera, Nigel P. Smart	Certification of Public Keys within an Identity Based System.	ISC	2002	DBLP DOI BibTeX RDF
19	Yanjiang Yang, Feng Bao 0001, Robert H. Deng	Security Analysis and Improvement of the Global Key Recovery System.	ACISP	2002	DBLP DOI BibTeX RDF
19	Olivier Baudron, Pierre-Alain Fouque, David Pointcheval, Jacques Stern, Guillaume Poupard	Practical multi-candidate election system.	PODC	2001	DBLP DOI BibTeX RDF
19	Adam L. Young, Moti Yung	Towards Signature-Only Signature Schemes.	ASIACRYPT	2000	DBLP DOI BibTeX RDF	Public Key Cryptosystems (PKCS), nested trapdoor, abuse freeness, (subliminal) leakage, design validation proofs, FIPS, digital signature, decryption, Public Key Infrastructure (PKI), NIST
19	Albert Levi, M. Ufuk Çaglayan	An Efficient, Dynamic and Trust Preserving Public Key Infrastructure.	S&P	2000	DBLP DOI BibTeX RDF	Nested Certificates, Performance Evaluation, Digital Certificates, Public Key Infrastructure (PKI), Certificate Path
19	Manolis Marazakis, Dimitris Papadakis, Christos Nikolaou, Penelope Constanta	System-Level Infrastructure Issues for Controlled Interactions among Autonomous Participants in Electronic Commerce Processes.	DEXA Workshops	1999	DBLP DOI BibTeX RDF	distributed component framework, distributed dynamic workflow, service-level management
19	Richard B. Neely	Security Architecture Development and Results for a Distributed Modeling and Simulation System .	ACSAC	1999	DBLP DOI BibTeX RDF	information security, modeling and simulation, security architecture, accreditation
19	Anas Tarah, Christian Huitema	Associating Metrics to Certification Paths.	ESORICS	1992	DBLP DOI BibTeX RDF
19	Oliver Antons, Julia C. Arlinghaus	Designing distributed decision-making authorities for smart factories - understanding the role of manufacturing network architecture.	Int. J. Prod. Res.	2024	DBLP DOI BibTeX RDF
19	Arihant Chadda, Sean McGregor, Jesse Hostetler, Andrea Brennen	AI Evaluation Authorities: A Case Study Mapping Model Audits to Persistent Standards.	AAAI	2024	DBLP DOI BibTeX RDF