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Petri net

Petri net
A Petri net (also known as a place/transition net or P/T net) is one of several mathematical modeling languages for the description of distributed systems. A Petri net is a directed bipartite graph, in which the nodes represent transitions (i.e. events that may occur, signified by bars) and places (i.e. conditions, signified by circles). The directed arcs describe which places are pre- and/or postconditions for which transitions (signified by arrows). Some sources[1] state that Petri nets were invented in August 1939 by Carl Adam Petri — at the age of 13 — for the purpose of describing chemical processes. Like industry standards such as UML activity diagrams, BPMN and EPCs, Petri nets offer a graphical notation for stepwise processes that include choice, iteration, and concurrent execution. (a) Petri net trajectory example Petri net basics[edit] A Petri net consists of places, transitions, and arcs. Graphically, places in a Petri net may contain a discrete number of marks called tokens.

Petri net Figure 1: Example of a production net. A Petri net is a graphical tool for the description and analysis of concurrent processes which arise in systems with many components (distributed systems). The graphics, together with the rules for their coarsening and refinement, were invented in August 1939 by the German Carl Adam Petri - at the age of 13 - for the purpose of describing chemical processes, such as Figure 1. Anatomy of a Petri net The components of these nets are called states (for substances) and transitions (for reactions). The round symbols denote states (also called places or, more abstractly, conditions); the rectangular shapes denote transitions They are interconnected by arrows which show the direction of flow. By convention, the state symbols of regularly built nets are often omitted, in order to show their abstract structure more clearly, which may result in surprising shapes ( Figure 2). Figure 2: Figure 3: Figure 4: General net theory Figure 5: Figure 6: Figure 7: Figure 8:

Actor model History[edit] Major software implementation work was done by Russ Atkinson, Giuseppe Attardi, Henry Baker, Gerry Barber, Peter Bishop, Peter de Jong, Ken Kahn, Henry Lieberman, Carl Manning, Tom Reinhardt, Richard Steiger and Dan Theriault in the Message Passing Semantics Group at Massachusetts Institute of Technology (MIT). Research groups led by Chuck Seitz at California Institute of Technology (Caltech) and Bill Dally at MIT constructed computer architectures that further developed the message passing in the model. Research on the Actor model has been carried out at California Institute of Technology, Kyoto University Tokoro Laboratory, MCC, MIT Artificial Intelligence Laboratory, SRI, Stanford University, University of Illinois at Urbana-Champaign,[6] Pierre and Marie Curie University (University of Paris 6), University of Pisa, University of Tokyo Yonezawa Laboratory and elsewhere. Fundamental concepts[edit] The Actor model adopts the philosophy that everything is an actor.

Smart Mobs: Jimbo (Wikipedia) Wales calls for Wiki Politics Think-Know Tools is an extension for the Introduction to Mind-Amplifiers course. It covers subjects like intellect augmentation, personal knowledge management, mind-amplifying devices, self-evolving collective intelligence networks, knowledge technologies. It involves new unconventional teaching and learning methods like asynchronous forums, blogs, wikis, mindmaps, social bookmarks, concept maps, Personal Brain, and synchronous audio, video, chat, and Twitter. The duration of the course is 6 weeks between October 17 and November 30, along 6 weekly modules, as follows: Module 1: Roots & Visions of AugmentationModule 2: Social Bookmarking as Collective IntelligenceModule 3: Concept MappingModule 4: Personal Knowledge ManagementModule 5: The Extended MindModule 6: Self-Organized Co-Learning Important note about participation If you’re interested in registering for this course, you should know that the course is collaborative and participative, not a passive enjoyment of online lectures.

Organization An organization (or organisation) is a social entity, such as an institution or an association, that has a collective goal and is linked to an external environment. The word is derived from the Greek word organon, itself derived from the better-known word ergon which means "organ" . Types of organization[edit] There are a variety of legal types of organizations, including corporations, governments, non-governmental organizations, international organizations, armed forces, charities, not-for-profit corporations, partnerships, cooperatives, universities, and various types of political organizations. A hybrid organization is a body that operates in both the public sector and the private sector simultaneously, fulfilling public duties and developing commercial market activities. A voluntary association is an organization consisting of volunteers. Organizational structures[edit] The study of organizations includes a focus on optimizing organizational structure. Committees or juries[edit]

Social organism In sociology, the social organism is theoretical concept in which a society or social structure is viewed as a “living organism.” From this perspective, typically, the relation of social features, e.g. law, family, crime, etc., are examined as they interact with other features of society to meet social needs. All elements of a society or social organism have a function that maintains the stability and cohesiveness of the organism. History[edit] The model or concept of society as an organism was developed in the late 19th century by Émile Durkheim, a French sociologist. According to Durkheim, the more specialized the function of an organism or society the greater its development, and vice-versa. References[edit] MacLay, George R. (1990). External links[edit]

untitled Wikipedia is a free encyclopedia, collaboratively being constructed at the web site using the Wiki metaphor. There are four main differences between Wikipedia and E2: Editing: Nobody owns a node; (almost) everything can be edited by anybody, even without logging in. History The project was started in January 2001 by Larry Sanger, a philosophy Ph.D., and Jimbo Wales, an internet entrepreneur. The most important early actions by Sanger were the formulation and enforcement of the NPOV policy, setting up the site's general link structure, and the weeding out of non-encyclopedic materials. In 2001, RMS endorsed Wikipedia as the embodiment of GNUpedia, a project of constructing a free encyclopedia and learning resource which he had envisioned earlier. Many hundred writers contribute on a regular basis. Occasionally, obnoxious users ("vandals") have to be banned from the site. As of August 2005, Wikipedia contained more than 700,000 genuine encyclopedia articles.

Who Runs Wikipedia? (Aaron Swartz's Raw Thought) During Wikimania, I gave a short talk proposing some new features for Wikipedia. The audience, which consisted mostly of programmers and other high-level Wikipedians, immediately begun suggesting problems with the idea. “Won’t bad thing X happen?” At the time, I was just happy this quieted them down. It wasn’t because its programmers were so far-sighted that the software solved all the problems. No, the reason Wikipedia works is because of the community, a group of people that took the project as their own and threw themselves into making it succeed. People are constantly trying to vandalize Wikipedia, replacing articles with random text. Why does anyone do such a thing? It’s hard to imagine anyone feeling this way about Britannica. Everybody knows Wikipedia as the site anyone can edit. But what’s less well-known is that it’s also the site that anyone can run. This is so unusual, we don’t even have a word for it. But Wikipedia’s openness isn’t a mistake; it’s the source of its success.

Problem solving Problem solving consists of using generic or ad hoc methods, in an orderly manner, for finding solutions to problems. Some of the problem-solving techniques developed and used in artificial intelligence, computer science, engineering, mathematics, medicine, etc. are related to mental problem-solving techniques studied in psychology. Definition[edit] The term problem-solving is used in many disciplines, sometimes with different perspectives, and often with different terminologies. For instance, it is a mental process in psychology and a computerized process in computer science. Problems can also be classified into two different types (ill-defined and well-defined) from which appropriate solutions are to be made. Psychology[edit] While problem solving accompanies the very beginning of human evolution and especially the history of mathematics,[4] the nature of human problem solving processes and methods has been studied by psychologists over the past hundred years. Clinical psychology[edit]

Ross Mayfields Weblog: Heavy Lifting One interesting Wikimania session by Seth Anthony presented some research on contribution patterns. My notes: Only 10% of edits are high content edits. 30% of those are anonymous, none are by admins, 52% are by someone with a userpage, none have a barnstar. The people who are creating content are relatively new, not versed in style guides and bureaucracy. Their use of Wikipedia speeds up a little bit through use, but not much. In other words, the core community within the Power Law of Participation, the 500 people that do 50% of the edits, or 0.5% of the registered population -- does the heavy lifting for subject experts. I should highlight, as with most things, Wikipedia is an exception for wiki communities.

Leet One way to write the word "Wikipedia" in Leet Leet (or "1337"), also known as eleet or leetspeak, is an alternative alphabet for the English language that is used primarily on the Internet. It uses various combinations of ASCII characters to replace Latinate letters. For example, leet spellings of the word leet include 1337 and l33t; eleet may be spelled 31337 or 3l33t. History Leet symbols, especially the number 1337, are Internet memes that have spilled over into popular culture. Orthography One of the hallmarks of leet is its unique approach to orthography, using substitutions of other characters, letters or otherwise, to represent a letter or letters in a word.[4][5] For more casual use of leet, the primary strategy is to use homoglyphs, symbols that closely resemble (to varying degrees) the letters for which they stand. Morphology Text rendered in leet is often characterized by distinctive, recurring forms. The -xor suffix The -age suffix The -ness suffix Words ending in -ed Grammar n00b Pr0n

Database download Wikipedia offers free copies of all available content to interested users. These databases can be used for mirroring, personal use, informal backups, offline use or database queries (such as for Wikipedia:Maintenance). All text content is multi-licensed under the Creative Commons Attribution-ShareAlike 3.0 License (CC-BY-SA) and the GNU Free Documentation License (GFDL). Images and other files are available under different terms, as detailed on their description pages. For our advice about complying with these licenses, see Wikipedia:Copyrights. Where do I get... English-language Wikipedia[edit] Dumps from any Wikimedia Foundation project: Wikipedia dumps in SQL and XML: – Current revisions only, no talk or user pages. Other languages[edit] In the directory you will find the latest SQL and XML dumps for the projects, not just English. Dealing with compressed files[edit]

Jimmy Wales Wikipedia, the free encycloped Free multilingual online encyclopedia Wikipedia has received praise for its enablement of the democratization of knowledge, extent of coverage, unique structure, culture, and reduced degree of commercial bias; but criticism for exhibiting systemic bias, particularly gender bias against women and alleged ideological bias.[13][14] Its reliability was frequently criticized in the 2000s but has improved over time, as Wikipedia has been generally praised in the late 2010s and early 2020s.[3][13][15] The website's coverage of controversial topics such as American politics and major events like the COVID-19 pandemic has received substantial media attention. It has been censored by world governments, ranging from specific pages to the entire site. Nevertheless, Wikipedia has become an element of popular culture, with references in books, films, and academic studies. History Nupedia Wikipedia originally developed from another encyclopedia project called Nupedia. Launch and growth Milestones Openness