# Wikipedia's fixed point

(by Bob West, May 26, 2011)

The other day my friend Peter pointed me towards this xkcd comic: http://xkcd.com/903/

The interesting part is actually hidden in the rollover (the text that appears when you point your mouse cursor over the image). It says,

"Wikipedia trivia: if you take any article, click on the first link in the article text not in parentheses or italics, and then repeat, you will eventually end up at 'Philosophy'."

Peter mused, "Now is that intentionally engineered into the system, or does it have to do with philosophy being a conceptual attractor to everything?"

This is where Wikipedia-based procrastination got me again. I spent a day (a day I should normally have spent working) thinking about and experimenting with this. So I thought I might as well share the results.

Here is a picture that captures the scenario:

(I made a little mistake drawing the picture: I included the article "Vertebrate" twice; "Boa" has to link directly to "Mammal" in the inner cycle.)

In this picture, F0 is the set of all Wikipedia articles. Each article has exactly one "first-link successor", marked by an arrow from the article to its successor. F1 is the subset of all Wikipedia articles (i.e., of F0) consisting of all articles that are first-link successors of any Wikipedia article (i.e., of any element of F0). F2 is the set of all first-link successors of the articles in F1, F3 is the set of all first-link successors of F2, and so forth, up to a point FN where all successors of FN are themselves in FN (in other words, FN+1 = FN), such that further applying the successor function does not shrink the set of articles any more. This irreducible core FN necessarily consists of cycles only.

The article about philosophy is in one of these cycles. Whatever article you start from, you will in a few hops traverse the layers shown in the picture. You'll probably not hit each single one of them, but you'll always gravitate from the outside towards the center of the picture, finally ending up in one of the cycles of the irreducible core. Now, when you continue clicking, you'll hit the same articles over and over again, in the same order. That means that, if the cycle you hit is the one of which "Philosophy" is a member, you'll eventually end up at "Philosophy".

As a concrete example of manageable size, let's look at a small version of Wikipedia (the one also used in Wikispeedia), with which you can play here. These are the numbers: There are 4,604 articles in total, and there are 19 distinct layers F0 to F18 (cf. the picture), i.e., after at most 18 clicks, you'll hit a cycle. There are 38 cycles containing a total of only 88 articles (out of all the 4,604 articles!). The biggest cycle contains 11 articles:

[Culture, Anthropology, Human, Mammal, Vertebrate, Cambrian_explosion, Fossil, Mineral, Geology, Science, Society],

the next biggest one has 5 members:

[Economics, Education, Family, Sociology, Globalization],

and all remaining 36 cycles have only two members, each member having the other as its first-link successor, e.g. [Cotton, Textile]. So after at most 18 clicks, you are in one of the 88 articles of the irreducible core, and there's a big chance the cycle you're in is the large one with 11 elements. If that's the case, by clicking at most 10 more times you'll hit a fixed "magic" article, such as "Anthropology". Note that in this small version of Wikipedia (as opposed to "real" Wikipedia), you probably shouldn't pick "Philosophy" as your magic article, since it's not in the big cycle but in a tiny two-element cycle [Philosophy, Logic].

I pasted the data resulting from my experiment at the bottom of this page. (With these data you could in principle complete the above picture for the concrete case of the small Wikipedia version.)

By the way, it turns out there is a card trick that works exactly the same way. It's called the "Kruskal Count", and you can find a nice demo of it here.

So let's wrap up by returning to Peter's question (you realize how this post is itself a cycle from Peter back to Peter...) whether the phenomenon from the xkcd comic is (1) "intentionally engineered into the system" or (2) caused by "philosophy being a conceptual attractor to everything". The answer is that both play a role: (1) It only works because "Philosophy" is part of one of the core cycles, so to an extent the effect is engineered into the structure of Wikipedia's hyperlink network (mostly not intentionally, although some people have tinkered with articles in order to make or break the xkcd effect). (2) The first paragraph of Wikipedia articles typically contains a definition, and as my friend Ashton put it, by following the first link over and over again, you act like a little child that keeps asking "But why?". So you're gravitating towards the "Philosophy" cycle most of time (and not to one of the other existing cycles), since the ultimate explanation of things is what philosophers are dealing with.

"But why?"

Layers and core cycles of the small Wikipedia version:

```F0 has size 4604; articles in F0 but not in F1: [%C3%81ed%C3%A1n_mac_Gabr%C3%A1in, %C3%85land, %C3%89douard_Manet, %C3%89ire, %C3%93engus_I_of_the_Picts, %E2%82%AC2_commemorative_coins, 13th_century, 14th_century, 15th_Marine_Expeditionary_Unit, 16_Cygni, 16_Cygni_Bb, 1755_Lisbon_earthquake, 1896_Summer_Olympics, 1928_Okeechobee_Hurricane, 1973_oil_crisis, 1980_eruption_of_Mount_St._Helens, 1997_Pacific_hurricane_season, 1_Ceres, 1st_century, 1st_century_BC, 2-8-0, 2004_Indian_Ocean_earthquake, 2005_Hertfordshire_Oil_Storage_Terminal_fire, 2005_Kashmir_earthquake, 2005_Lake_Tanganyika_earthquake, 2005_Sumatra_earthquake, 21st_century, 2nd_century, 3_Juno, 4-6-0, 47_Ursae_Majoris, 47_Ursae_Majoris_b, 47_Ursae_Majoris_c, 4_Vesta, 4th_century, 55_Cancri, 55_Cancri_b, 55_Cancri_c, 55_Cancri_d, 55_Cancri_e, 6-2-0, 90377_Sedna, A._E._J._Collins, AC_DC, AK-47, ALCO_FA, ASCII, AT%26T, ATLAS_experiment, A_Christmas_Carol, A_Tale_of_a_Tub, A_Wrinkle_in_Time, Aachen, Aardvark, Aarhus, Abac%C3%A1, Abacus, Abadan, Abbadid, Abbas_I_of_Persia, Abbasid, Abbey, Abbey_Theatre, Abel_Tasman, Aberration_of_light, Aberystwyth, Abkhazia, Able_Archer_83, Abraham_Goldfaden, Abraham_Lincoln, Absinthe, Absolute_zero, Abu_Dhabi, Abuja, Acceleration, Accountancy, Accra, Acetic_acid, Acetone, Achilles_tendon, Acid_rain, Acorn_Computers, Actinium, Acts_of_Union_1707, Actuary, Addis_Ababa, Adenosine_triphosphate, Adi_Shankara, Adriaen_van_der_Donck, Advertising, Afghan_Hound, African_American_literature, African_Black_Oystercatcher, African_Brush-tailed_Porcupine, African_Buffalo, African_Darter, African_Great_Lakes, African_Grey_Hornbill, African_Grey_Parrot, African_Jacana, African_Penguin, African_Union, African_Wild_Dog, African_clawed_frog, African_dwarf_frog, African_slave_trade, Agamemnon, Agnosticism, Airship, Ajax_%28programming%29, Akbar, Akhenaten, Akkadian_Empire, Akrotiri_and_Dhekelia, Aksumite_currency, Al_Jazeera, Alamosaurus, Alan_Turing, Albatross, 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Cathedral_of_Magdeburg, Catherine_Cranston, Catherine_II_of_Russia, Catholic_social_teaching, Cayman_Islands, Celeriac, Cell_%28biology%29, Cello, Celtic_F.C., Celtic_Park, Celtic_mythology, Central_African_Republic, Cerebellum, Ceres_%28dwarf_planet%29, Cerium, Chadian-Sudanese_conflict, Chaffinch, Charlemagne, Charles_Babbage, Charles_Etienne_Brasseur_de_Bourbourg, Charles_Sumner, Charles_V%2C_Holy_Roman_Emperor, Charlie_Chaplin, Charlotte%27s_Web, Chartism, Che_Guevara, Cheers, Cheese, Cheetah, Chelsea_F.C., Chennai, Chepstow_Bridge, Chernobyl_disaster, Chess, Chester_A._Arthur, Chestnut, Chew_Magna, Chew_Stoke, Chew_Valley_Lake, Chicago_Bears, Chicago_and_North_Western_Railway, Chicken, Children%27s_Crusade, Children%27s_rights_movement, Chinese_Rites_controversy, Chinyingi, Chives, Chola_dynasty, Cholera, Chordate, Chris_Evert, Christian_Bale, Christina_Aguilera, Christmas_Island, Christopher_Wren, Chromatic_aberration, Chromatophore, Chromium, Church_of_Ireland, Cicely, Cider, Citizen_Kane, Civil_War_token, Civil_society, Civilization_%28computer_game%29, Classic_female_blues, Claude_L%C3%A9vi-Strauss, Claude_Monet, Claudius, Cleopatra_VII, Cleopatra_VII_of_Egypt, Cleveland%2C_Ohio, Clifton_Suspension_Bridge, Clone_Wars_%28Star_Wars%29, Cloud, Coal_Tit, Cobalt, Coccinellidae, Cochineal, Cockatiel, Cocoa, Coconut_crab, Coconut_oil, Cocos_%28Keeling%29_Islands, Cod, Code_of_Hammurabi, Coffee, Colditz_Castle, Colima_%28volcano%29, Collapse_of_the_World_Trade_Center, Colley_Cibber, Cologne, Colombia, Colombo, Color_Graphics_Adapter, Color_blindness, Colossus_of_Rhodes, Columba, Columbia_River, Columbine_High_School_massacre, Columbus%2C_Ohio, Comet_Hale-Bopp, Comet_Halley, Comet_Hyakutake, Comet_Shoemaker-Levy_9, Comet_White-Ortiz-Bolelli, Comma_Johanneum, Common_Basilisk, Common_Cuckoo, Common_Eider, Common_Eland, Common_Hazel, Common_Pheasant, Common_Tern, Common_agouti, Common_cold, Common_sage, Commonwealth_Games, Community, Comoros, Company_%28law%29, Compsognathus, Computational_chemistry, Conakry, Concorde, Condoleezza_Rice, Conflict, Confucianism, Confucius, Congo_River, Consolation_of_Philosophy, Constantine_I, Constantine_II_of_Scotland, Constitution_of_May_3%2C_1791, Constructivism_%28art%29, Consumer_protection, Contact_lens, Control_car_%28rail%29, Convention_on_the_International_Trade_in_Endangered_Species_of_Wild_Flora_and_Fauna, Cook_Islands, Cookiecutter_shark, Cooperative, Coot, Copenhagen, Copenhagen_Fire_of_1728, Copper%28I%29_chloride, Corn_oil, Cornell_University, Coronation_Street, Corporate_finance, Corrosion, Corundum, Cosmic_microwave_background_radiation, Costa_Rica, Costume_design, Cotopaxi, Cotswolds, Coulomb%27s_law, Coupling_%28railway%29, Coventry, Crab_Nebula, Crash_test_dummy, Craters_of_the_Moon_National_Monument_and_Preserve, Craton, Creation-evolution_controversy, Creationism, Cretaceous-Tertiary_extinction_event, Crime_and_Punishment, Crime_in_Mexico, Crimean_Karaites, Crimean_War, 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Edmonton, Edmund_Burke, Edmund_Hillary, Education_in_the_United_States, Educational_psychology, Edward_Gibbon, Edward_II_of_England, Edward_IV_of_England, Edward_I_of_England, Edward_Jenner, Edward_Teller, Edward_VII_of_the_United_Kingdom, Edward_VI_of_England, Edward_V_of_England, Edward_the_Confessor, Edwin_of_Northumbria, Effect_of_Hurricane_Katrina_on_New_Orleans, Effects_of_global_warming, Effects_of_nuclear_explosions, Egg_%28food%29, Egyptian_pyramids, Eifel_Aqueduct, Eilmer_of_Malmesbury, Einsteinium, El_Aai%C3%BAn, El_Hatillo_Municipality%2C_Miranda, El_Lissitzky, El_Ni%C3%B1o-Southern_Oscillation, El_Salvador, Elagabalus, Eldfell, Electrical_engineering, Electron_beam_welding, Electronic_amplifier, Elementary_algebra, Elementary_arithmetic, Elementary_group_theory, Eleocharis_dulcis, Elephant_bird, Elephant_shrew, Elfin-woods_Warbler, Elias_Ashmole, Eliminative_materialism, Elizabeth_Fry, Elizabethan_Poor_Law_%281601%29, Elvis_Presley, Emacs, Emma_Roberts, Emperor_Penguin, Empires__Dawn_of_the_Modern_World, Empiricism, Emu, Enceladus_%28moon%29, Encyclop%C3%A6dia_Britannica, Endoscopic_foreign_body_retrieval, England_expects_that_every_man_will_do_his_duty, English_Reformation, English_monarchs_family_tree, English_peasants%27_revolt_of_1381, Enigma_machine, Entropy, Environmental_science, Enzyme_kinetics, Eocene, Epaminondas, Epazote, Epic_of_Gilgamesh, Episcopal_polity, Equal_Protection_Clause, Equatorial_Guinea, Erbium, Eric_Clapton, Erie_Canal, Eris_%28dwarf_planet%29, Eritrea, Ernest_Rutherford, Eruption_column, Erwin_Rommel, Eskimo, Esox, Esperanto, Ethiopian_Wolf, Euphrates, Eurasian_Bullfinch, Eurasian_Collared_Dove, Eurasian_Eagle_Owl, Eurasian_Jay, Eurasian_Oystercatcher, European_Goldfinch, European_Greenfinch, European_Kingfisher, Europium, Eurovision_Song_Contest, Euston_Manifesto, Eustreptospondylus, Eva_Per%C3%B3n, Evan_Rachel_Wood, Evanton, Evolutionarily_stable_strategy, Existentialism, Exploration_of_Mars, Explorer_I, Expressionism, 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George_W._Bush, Georgetown%2C_Guyana, Georgia_%28country%29, Gerald_Durrell, Gerald_Ford, German_Crusade%2C_1096, German_reunification, Germanium, Gettysburg_Address, Ghost_Dance, Giant%27s_Causeway, Giant_Eland, Giant_Hogweed, Giant_Panda, Giganotosaurus, Gilles_Villeneuve, Giraffe, Giuseppe_Verdi, Giza_pyramid_complex, Glacier_National_Park_%28US%29, Glaciology, Glasses, Glastonbury_Festival, GlaxoSmithKline, Gliding, Gliese_876, Gliese_876_b, Gliese_876_c, Gliese_876_d, Global, Global_city, Globe_Theatre, Globular_cluster, Glorious_Revolution, Glynn_Lunney, Gmail, Go_%28board_game%29, Goa, Gold%28III%29_chloride, Gold_standard, Goldcrest, Golden_Eagle, Golden_Gate_Highlands_National_Park, Goldfish, Goleta%2C_California, Gone_with_the_Wind_%28film%29, Google, Gordon_Brown, Gordon_Griffith, Gossypium, Gothenburg, Gottfried_Leibniz, Government_of_France, Gowanus_Canal, Grand_Canal_of_China, Grand_Canyon, Grand_Central_Station_%28Chicago%29, Grand_Central_Terminal, 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History_of_Solidarity, History_of_South_Africa, History_of_South_Africa_in_the_apartheid_era, History_of_South_Carolina, History_of_Wikipedia, History_of_computing_hardware, History_of_democracy, History_of_education, History_of_merit_badges_%28Boy_Scouts_of_America%29, History_of_nuclear_weapons, History_of_painting, History_of_post-Soviet_Russia, History_of_saffron, History_of_slavery, History_of_the_Australian_Capital_Territory, History_of_the_Grand_Canyon_area, History_of_the_Internet, History_of_the_Netherlands, History_of_the_Panama_Canal, History_of_the_Portuguese_Communist_Party, History_of_the_Royal_Australian_Navy, History_of_the_West_Indian_cricket_team, Ho_Chi_Minh, Ho_Chi_Minh_City, Holkham_Hall, Hollandic, Holmium, Homestar_Runner, Homo_floresiensis, Honey, Honey_bee, Hoover_Dam, Hopman_Cup, Horatio_Nelson%2C_1st_Viscount_Nelson, Hot_air_balloon, House_Martin, House_Sparrow, House_of_Lords, Household_income_in_the_United_States, Houston%2C_Texas, Hovercraft, Howards_End, Howland_Island, Hrafnkels_saga, Hubbard_Glacier, Hubble%27s_law, Hudson_Bay, Hugo_Wolf, Human_abdomen, Human_dignity, Humanism, Humanities, Humbert_Roque_Versace, Humour, Humpback_Whale, Humphry_Davy, Humus, Hundred_Years%27_War, Hunger, Huntington%27s_disease, Hurricane_Alex_%282004%29, Hurricane_Andrew, Hurricane_Camille, Hurricane_Charley, Hurricane_Danny_%281997%29, Hurricane_David, Hurricane_Dennis, Hurricane_Edouard_%281996%29, Hurricane_Epsilon_%282005%29, Hurricane_Felix_%281995%29, Hurricane_Floyd, Hurricane_Georges, Hurricane_Gloria, Hurricane_Ivan, Hurricane_John_%281994%29, Hurricane_John_%282006%29, Hurricane_Lenny, Hurricane_Marty_%282003%29, Hurricane_Mitch, Hurricane_Philippe_%282005%29, Hurricane_Vince_%282005%29, Husein_Grada%C5%A1%C4%8Devi%C4%87, Hutu, Hyde_Park%2C_London, Hydrogen_peroxide, Hydrology, Hyena, Hymenoptera, Hypsilophodon, IG_Farben_Building, I_Ching, I_Want_to_Hold_Your_Hand, Ibn_Battuta, Ice, Ice_hockey, Iceland_hotspot, Ichthyosaur, Idit_Harel_Caperton, Idolatry, Igor_Stravinsky, Iguanodon, Ike_Altgens, Imagism, Income_disparity, Indian_Institutes_of_Technology, Indian_Peafowl, Indian_Railways, Indian_Standard_Time, Indian_cricket_team, Indira_Gandhi, Indium, Indo-Greek_Kingdom, Indonesian_language, Indricotherium, Inductance, Indus_River, Industrial_Revolution, Infrastructure, Inner_Hebrides, Insulin, Intel_Corporation, Intelligence, InterBase, International_Court_of_Justice, International_English, International_Red_Cross_and_Red_Crescent_Movement, International_Space_Station, Interpol, Introduction_to_special_relativity, Invasion_of_Grenada, Investment_banking, Iodine, Iranian_peoples, Iraq_War, Iraq_and_weapons_of_mass_destruction, Ireland_King_of_Arms, Irish_poetry, Irish_theatre, Iron%28III%29_chloride, Iron_Maiden, Iron_Mike, Irrigation, Isaac, Isaac_Brock, Isan, Ishango_bone, Isis, Islamic_republic, Island_Fox, Isle_of_Wight, Isles_of_Scilly, Isospin, Issyk_Kul, Istanbul, Italo_disco, Ivan_IV_of_Russia, Ivory, Ivory-billed_Woodpecker, J%C3%B3rv%C3%ADk, J%C3%B3zef_Pi%C5%82sudski, J._J._Thomson, J._K._Rowling, J._M._W._Turner, J._S._Fry_%26_Sons, Jack_Kerouac, Jackal, Jackanory, Jackdaw, Jackie_Robinson, Jacob_Riis, Jacobite_rising, Jacques-Louis_David, Jacques_Cartier, Jake_Gyllenhaal, James_Bond, James_Buchanan, James_Callaghan, James_Cook, James_D._Watson, James_Garfield, James_I_of_England, James_Joyce, James_K._Polk, James_Lovelock, James_Monroe, James_Stewart_%28actor%29, James_T._Aubrey%2C_Jr., James_Watt, Jan_Mayen, Jane_Eyre, Jane_Fonda, Japanese_grammar, Japanese_war_crimes, Japanese_yen, Jarvis_Island, Jaws_%28film%29, Jean-Jacques_Rousseau, Jean_Charles_de_Menezes, Jehovah, Jerry_Fodor, Jersey_Zoological_Park, Jesse_Owens, Jet_Set_Willy, Jet_engine, Jewellery, Jiaogulan, Jimmy_Carter, Jimmy_Wales, Joan_of_Arc, Jocelin, Joel_Brand, Johann_Pachelbel, Johann_Sebastian_Bach, Johann_Wolfgang_Goethe, Johannes_Gutenberg, Johannes_Kepler, Johannes_Ockeghem, John_A.T._Robinson, John_Adams, John_Bull_%28locomotive%29, John_Cabot, John_Calvin, John_Constable, John_Dee, John_F._Kennedy, John_F._Kennedy_assassination, John_Flamsteed, John_Henninger_Reagan, John_Howard, John_Logie_Baird, John_Marshall, John_Maynard_Keynes, John_McEnroe, John_Millington_Synge, John_Milton, John_Pershing, John_Seigenthaler%2C_Sr., John_Sentamu, John_Tyler, John_Vanbrugh, John_W._Campbell, John_W._Johnston, John_von_Neumann, Johnny_Appleseed, Johnston_Atoll, Jomsvikings, Jonah_Lomu, Jonathan_Wild, Jordanhill_railway_station, Jorge_Luis_Borges, Joseph_Haydn, Joseph_Stalin, Joseph_and_the_Amazing_Technicolor_Dreamcoat, Josephus, Juan_Sebasti%C3%A1n_Elcano, Juice, Julius_Caesar, Julius_and_Ethel_Rosenberg, July_2006_Java_earthquake, Jump_rope, Juniper_berry, Jupiter_%28mythology%29, Juvenile_delinquency, Jyllands-Posten_Muhammad_cartoons_controversy, K%C4%ABlauea, Kaffir_lime, Kakapo, Kakariki, Kansas_City%2C_Missouri, Karachi, Kargil_War, Karikkoselk%C3%A4, Karl_Benz, Karl_Popper, Kashmir_region, Katana, Katyn_massacre, Keira_Knightley, Kerala, Kestrel, Keurusselk%C3%A4, Kevin_Spacey, Khan_Wali_Khan, Khartoum, Khazars, Khudai_Khidmatgar, Kidnapped_%28novel%29, Kigali, Kigo, King_Arthur, King_Kong_%281933_film%29, King_Kong_%282005_film%29, Kingman_Reef, Kipchaks_in_Georgia, Kiribati, Kite_%28bird%29, Kitsch, Klinefelter%27s_syndrome, Knights_of_Columbus, Kochi_%28India%29, Kofi_Annan, Kohlberg%27s_stages_of_moral_development, Kolkata, Konrad_Lorenz, Kookaburra, Korea, Koryaksky, Kosovo, Krag-J%C3%B8rgensen, Krakatoa, Krazy_Kat, Krill, Krypton, Ku_Klux_Klan, Kuala_Lumpur, Kubla_Khan, Kuiper_belt, Kurt_Cobain, Kuru_%28disease%29, Kuwait, Kuwait_City, Kylie_Minogue, Kyoto_Protocol, L._S._Lowry, LANSA_Cuzco_Crash, La_Grande_Arm%C3%A9e, La_Paz, Labor_Day_Hurricane_of_1935, Ladysmith_Black_Mambazo, Lagos, Laika, Lake_Albert, Lake_Baikal, Lake_Burley_Griffin, Lake_Chad, Lake_Edward, Lake_Kariba, Lake_Kivu, Lake_Malawi, Lake_Mead, Lake_Powell, Lake_Superior, Lake_Tahoe, Lake_Tanganyika, Lake_Titicaca, Lake_Toba, Lake_Turkana, Lake_Victoria, Lake_Vostok, Lance_Armstrong, Lancia_Flaminia, Land_%28economics%29, Lanthanum, Laozi, Las_Palmas_de_Gran_Canaria, Las_Vegas%2C_Nevada, Last_Supper, Latin_alphabet, Laurence_Olivier, Laurent_Fignon, Lavender, Lawn, Lawrencium, Laws_in_Wales_Acts_1535%E2%80%931542, Layla, Lead%28II%29_nitrate, League_of_Nations, Leaning_Tower_of_Pisa, Lebanon, Leeds, Leicester, Leif_Ericson, Lemon_balm, Lemon_myrtle, Lens_%28anatomy%29, Leo_%28constellation%29, Leo_Tolstoy, Leon_Trotsky, Leonhard_Euler, Lerwick, Lesotho, Lesothosaurus, Levee_failures_in_Greater_New_Orleans%2C_2005, Lhasa, Liberal_Democrats, Library, Library_of_Alexandria, Library_of_Congress, Libreville, Liechtenstein, Lighthouse_of_Alexandria, Lighting_designer, Lightning_rod, Lilongwe, Lincoln_%28automobile%29, Lincoln_Town_Car, Lindisfarne_Gospels, Linear_algebra, Link_%28The_Legend_of_Zelda%29, Linnet, Linus_Pauling, Linus_Torvalds, Lipid, Liquid_crystal, List_of_African_countries, List_of_Archbishops_of_Canterbury, List_of_Asian_countries, List_of_Canadian_provinces_and_territories_by_area, List_of_European_Union_member_states_by_accession, List_of_European_countries, List_of_North_American_countries, List_of_Oceanian_countries, List_of_Prime_Ministers_of_the_United_Kingdom, List_of_South_American_countries, List_of_Test_cricket_triple_centuries, List_of_U.S._states_by_date_of_statehood, List_of_animal_welfare_groups, List_of_areas_in_the_National_Park_System_of_the_United_States, List_of_circulating_currencies, List_of_countries, List_of_countries_by_system_of_government, List_of_elements_by_name, List_of_essential_oils, List_of_lakes, List_of_members_of_the_Commonwealth_of_Nations_by_date_joined, List_of_minerals, List_of_particles, List_of_popes, List_of_rivers_by_length, List_of_universities_in_the_United_Kingdom, List_of_vegetable_oils, List_of_world%27s_largest_lakes, Literacy, Lithium, Lithium_aluminium_hydride, Little_Women, Liverpool_F.C., Llandudno, Llywelyn_the_Great, Local_community, Local_government_in_the_United_Kingdom, Loch_Ness, Logba_language, Logistics, Lom%C3%A9, London_Underground, London_Zoo, London_sewerage_system, Lone_Wolf_%28gamebooks%29, Long-billed_Vulture, Long-tailed_Tit, Long_pepper, Longship, Looney_Tunes, Lope_de_Barrientos, Lord%27s_Resistance_Army, Lord_Voldemort, Los_Angeles%2C_California, Lost_%28TV_series%29, Lothal, Lottie_Dod, Louis_Armstrong, Louis_Freeh, Louis_Jordan, Louis_Pasteur, Louis_XIV_of_France, Louisville%2C_Kentucky, Lovage, Love, Lucy%2C_Lady_Duff-Gordon, Ludwig_Wittgenstein, Ludwig_van_Beethoven, Luftwaffe, Lunar_eclipse, Lung_cancer, Lusaka, Luxembourg, Luxembourg_%28city%29, Lyme_disease, Lyndon_B._Johnson, Lynton_and_Barnstaple_Railway, Lyon, M%2AA%2AS%2AH_%28TV_series%29, M-10001, M-10003-6, M25_motorway, M6_motorway, MINI_%28BMW%29, Macau, Macbeth, Macbeth_of_Scotland, Machu_Picchu, Mackenzie_River, Madama_Butterfly, Madrid, Magdalena_Abakanowicz, 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Mary_Somerville, Maseru, Mass_Rapid_Transit_%28Singapore%29, Massospondylus, Mathematical_analysis, Matilda_of_Boulogne, Matrix_%28mathematics%29, Matsuo_Bash%C5%8D, Matthew_Brettingham, Mauna_Loa, Mauritania, Mausoleum_of_Maussollos, Mauthausen-Gusen_concentration_camp, Max_Planck, Max_Weber, Maxwell%27s_equations, Maya_mythology, Mayotte, Mbabane, McFly_%28band%29, Measles, Meat, Mecca, Medal_of_Honor, Medieval_commune, Medieval_literature, Medieval_music, Mega_Man_X_%28character%29, Meitnerium, Mekong, Mendelevium, Meningitis, Menstrual_cycle, Menthol, Mercantilism, Mercia, Mercury_%28element%29, Mercury_%28planet%29, Merrimack_River, Merseburg_Incantations, Mestizo, Metallurgy, Metamorphic_rock, Meteor, Meteor_shower, Meteorological_history_of_Hurricane_Katrina, Metric_expansion_of_space, Mexico_City, Miami%2C_Florida, Michael_Faraday, Michael_Jordan, Michael_Ramsey, Michael_Woodruff, Mickey_Mantle, Microraptor, Midway_Atoll, Miguel_de_Cervantes, Mikhail_Gorbachev, Milan, Miles_Davis, Milgram_experiment, Military_dictatorship, Military_history_of_Canada, Military_history_of_France, Military_history_of_Puerto_Rico, Military_history_of_the_Soviet_Union, Milk_thistle, Milkshake, Millard_Fillmore, Milton_Keynes, Ming_Dynasty, Mini, Minimum_wage, Minmi_%28dinosaur%29, Minneapolis%2C_Minnesota, Minoan_civilization, Minstrel_show, Mir, Mirabilis_%28plant%29, Miranda_Otto, Mistle_Thrush, Mitochondrial_Eve, Mitochondrion, Mixed-breed_dog, Mixtape, Modern_history, Modernist_poetry_in_English, Mohs_scale_of_mineral_hardness, Moldovans, Mole_%28animal%29, Molybdenum, Momentum, Monaco, Monaco_Grand_Prix, Monarchies_in_the_European_Union, Monarda_didyma, Mongol_invasion_of_Central_Asia, Mongoose, Monkey, Monoclonius, Monopoly_%28game%29, Monrovia, Montevideo, Montreal_Metro, Montserrat, Monty_Python, Moon_landing, Moore%27s_Law, Moorgate, Moorhen, Morecambe_Bay, Morecambe_and_Wise, Moringa_oleifera, Mormon, Mormon_Trail, Morphine, Morris_dance, Mosaic, Mosque, Mother_Teresa, Motion_%28physics%29, Mount_Baker, Mount_Everest, Mount_Kilimanjaro, Mount_Nyiragongo, Mount_Osmond%2C_South_Australia, Mount_Pinatubo, Mount_Rainier, Mount_Rushmore, Mount_St._Helens, Mount_Unzen, Mount_Vesuvius, Mountain_Gorilla, Mozambique, Mozilla_Firefox, Mu_Arae, Muhammad_Ali, Muhammad_Ali_Jinnah, Muhammad_Iqbal, Muhammad_ibn_Musa_al-Khwarizmi, Multiculturalism, Multiple_sclerosis, Multiple_sequence_alignment, Mumbai, Mummy, Munich, Murray_River, Muscat%2C_Oman, Music_of_Albania, Music_of_Antigua_and_Barbuda, Music_of_Barbados, Music_of_Dominica, Music_of_Hawaii, Music_of_Hungary, Music_of_Italy, Music_of_Martinique_and_Guadeloupe, Music_of_New_Zealand, Music_of_Spain, Music_of_Thailand, Music_of_Trinidad_and_Tobago, Music_of_the_Bahamas, Music_of_the_Lesser_Antilles, Music_of_the_United_States, Music_of_the_trecento, Muttaburrasaurus, Myco-heterotrophy, Myers-Briggs_Type_Indicator, Myocardial_infarction, Mysticism, Myxobolus_cerebralis, Nadia_Com%C4%83neci, Nagorno-Karabakh_War, Nahuatl_language, Nairobi, Naked_Mole_Rat, Names_of_God_in_Judaism, Namibia, Nanomedicine, Napster, Nash_equilibrium, Nashville%2C_Tennessee, Natalie_Portman, Nathu_La, National_Anthem_of_Russia, National_Gallery%2C_London, National_Hockey_League, National_parks_of_England_and_Wales, Natural_gas, Natural_selection, Nauru, Naval_Battle_of_Guadalcanal, Nazism, Necktie, Negros_Oriental, Neighbours, Neil_Young, Nelson_Mandela, Nematode, Neoclassicism, Neodymium, Neon, Nepenthes_rajah, Nephron, Neptune, Neptunium, Netherlands_Antilles, New_Caledonia, New_Delhi, New_England_Patriots, New_Forest, New_York_City_Subway_nomenclature, New_moon, Newark%2C_New_Jersey, Newcastle_upon_Tyne, Newmarket, Newshounds, Newsround, Niagara_Falls, Niccol%C3%B2_Machiavelli, Niccol%C3%B2_Paganini, Niccol%C3%B2_dell%27Abbate, Nicobar_Long-tailed_Macaque, Nicolaus_Copernicus, Niels_Bohr, Nigella, Niger, Nightingale, Nikola_Tesla, Nikolai_Rimsky-Korsakov, Nile, Nine_Million_Bicycles, Nineteen_Eighty-Four, Nintendo_DS, Niobium, Nirvana_%28band%29, Nitrification, Nitrogen_cycle, Nitrogen_fixation, Niue, Noam_Chomsky, Nobel_Peace_Prize, Nobelium, Nobiin_language, Norfolk_Island, Norman_Borlaug, North_Atlantic_oscillation, North_Sea_flood_of_1953, North_Sea_oil, Northern_Ireland, Northern_Mariana_Islands, Northern_Pacific_Railway, Northwest_Africa, Norwich, Nostradamus, Nottingham, Nouakchott, Novelty_%28locomotive%29, Nuclear_power, Number, Numismatics, Nurse_sharks, Nuthatch, Nutmeg, Oasis_%28band%29, Oat, Obi-Wan_Kenobi, Oceanography, Odin, Odysseus, Oenothera, Ohm, Oil_painting, Oil_refinery, Oil_reservoir, Okapi, Olaudah_Equiano, Old_Swiss_Confederacy, Oleg_of_Novgorod, Olive_oil, Oliver_Cromwell, Oliver_Twist, Ollanta_Humala, Olmec, Oman, Omega-3_fatty_acid, One_Flew_Over_the_Cuckoo%27s_Nest_%28novel%29, One_Foot_in_the_Grave, Onion_dome, OpenBSD, OpenOffice.org, Oppression, Optical_fiber, Optical_microscope, Opuntia_imbricata, Opus_Dei, Orbit_%28anatomy%29, Orca, Order_of_St._Patrick, Ordinary_differential_equation, Ordination_of_women, Oregano, Oregon, Organization, Orion_Nebula, Orkney, Ormulum, Ornithischia, Oroonoko, Osama_bin_Laden, Osiris, Oslo, Osprey, Osteomalacia, Ostrich, Oswald_of_Northumbria, Ottawa, Otter, Otto_von_Bismarck, Ouagadougou, Overseas_Railroad, Oviraptor, Oxford, Oxyrhynchus, Ozone_depletion, P%C3%B3voa_de_Varzim, PONG, PRR_GG1, PRR_M1, PSR_B1620-26c, Pablo_Picasso, Pac-Man, Pachycephalosaurus, Palace_of_Westminster, Palazzo_Pitti, Palestinian_territories, Palio_di_Siena, Palladian_architecture, Palladium, Palm_oil, Palmyra_Atoll, Pan_Am_Flight_103, Panama, Panama_Canal, Pandanus, Papal_conclave, Paprika, Paraguay, Parasaurolophus, Paricut%C3%ADn, Park, Parliament_of_Malaysia, Parliamentary_system, Parsley, Parsnip, Parthenon, Pashtun_people, Passenger_Pigeon, Pat_Cash, Patna, Paul_C%C3%A9zanne, Paul_Dirac, Paul_Kane, Paul_McCartney, Paul_of_Tarsus, Pea, Peace, Peaceful_coexistence, Peafowl, Peak_District, Peanut, Pearl, Pedagogy, Pedro_del_Valle, Pel%C3%A9, Pelagic_zone, Pellagra, Pelycosaur, Penda_of_Mercia, Pennine_Way, People%27s_Republic_of_China, Pere_Marquette_1225, Peregrine_Falcon, Perfect_number, Pericles, Periodic_table_%28large_version%29, Pernicious_anemia, Persian_literature, Perth%2C_Western_Australia, Pete_Sampras, Peter_Grimes, Peter_I_of_Russia, Peter_Paul_Rubens, Peterborough_Chronicle, Phase_%28matter%29, Pheidippides, Phenylketonuria, Philadelphia, Philately, Philip_II_of_Spain, Philosophiae_Naturalis_Principia_Mathematica, Phineas_Gage, Phishing, Phla-Pher%C3%A1_languages, Phoenix_%28spacecraft%29, Phoenix_Zoo, Phonograph_cylinder, Phosphorus_tribromide, Phosphorus_trichloride, Phosphoryl_chloride, Photography, Photon, Photosynthetic_reaction_centre, Photovoltaic_array, Physical_paradox, Pi, Piccadilly_Circus, Picts, Pied_Avocet, Pig, Pigeon, Pigment, Pikachu, Pink_Pigeon, Pinworm, Pitcairn_Islands, Plains_Zebra, Planetary_habitability, Plant_cell, Plasma_%28physics%29, Plateosaurus, Plato, Platypus, Playing_card, Pleiades_%28star_cluster%29, Plesiosaur, Pliocene, Plum, Pluto, Plutonium, Plymouth, Pochard, Poetry_of_the_United_States, Poison_gas_in_World_War_I, Pok%C3%A9mon_Trading_Card_Game, Polar_coordinate_system, Polar_ice_cap, Police_state, Polish%E2%80%93Muscovite_War_%281605%E2%80%931618%29, Polish-Muscovite_War_%281605%E2%80%931618%29, Political_integration_of_India, Politics_of_the_United_Kingdom, Pollinator_decline, Polonium, Polymerase_chain_reaction, Pompeii, Pond, Pontiac%27s_Rebellion, Pony, Poor_Law, Pop_Idol, Pope_Benedict_XVI, Pope_John_Paul_II, Pope_Pius_XII, Popular_culture_studies, Population_history_of_American_indigenous_peoples, Porgy_and_Bess, Port_Louis, Porto-Novo, Portuguese_Communist_Party, Post-glacial_rebound, Postman_Pat, Potassium, Potassium_iodide, Potassium_nitrate, Potato, Pottery, Poverty, Praia, Praseodymium, Pre-Raphaelite_Brotherhood, Precambrian, Prehistoric_man, Pretoria, Pride_and_Prejudice, Primula, Princeton_University, Printmaking, Prion, Private_Peaceful, Pro_Milone, Probability_theory, Project_MKULTRA, Project_Vanguard, Promethium, Propaganda, Prospecting, Prostate_cancer, Protactinium, Protoceratops, Proton, Proxima_Centauri, Psittacosaurus, Pterosaur, Ptolemy, Publishing, Puffin, Pumpkin, Punctuated_equilibrium, Pupil, Pygmy_Hippopotamus, Pyongyang, Pyotr_Ilyich_Tchaikovsky, Pyramid, Pyrite, Pythagoras, Pythagorean_theorem, Python_%28programming_language%29, Qin_Dynasty, Qin_Shi_Huang, Qing_Dynasty, Quantum_chemistry, Quantum_computer, Quark, Quartz, Quatermass_and_the_Pit, Queen_%28band%29, Quetzalcoatl, Quito, Qur%27an, R%C3%A9union, RER, RMS_Titanic, ROT13, RSS_%28file_format%29, Rabat, Rabies, Rabindranath_Tagore, Radhanite, Radio_telescope, Radish, Radium, Radon, Rail_transport_in_India, Railway_post_office, Rainbow, Rainforest, Raising_the_Flag_on_Iwo_Jima, Ralph_Nader, Rama, Ramesses_II, Ramsgate, Ran_%28film%29, Raney_nickel, Raphael, Rapping, Raven, Ray_of_Light, Rebecca_Helferich_Clarke, Recycling, Red_Kite, Red_Panda, Red_Sea, Red_giant, Red_rain_in_Kerala, Redwing, Redwood_National_and_State_Parks, Reed_Bunting, Reed_Warbler, Refining, Refrigerator_car, Regent%27s_Park, Reggae, Reggaeton, Ren%C3%A9_Descartes, Renaissance_music, Renminbi, Renormalization, Republic_of_Macedonia, Republic_of_the_Congo, Restoration_literature, Retina, Retinol, Retreat_of_glaciers_since_1850, Revised_Standard_Version, Revolution, Reza_Shah, Rhine, Rhode_Island, Rhodium%28III%29_chloride, Rhubarb, Rice, Richard_Feynman, Richard_Francis_Burton, Richard_III_%28play%29, Richard_II_of_England, Richard_Nixon, Richard_O%27Connor, Richard_Wagner, Richmond%2C_Virginia, Riesling, Right_whale, Ringed_Plover, Rio_Tinto_Group, Rio_de_Janeiro, River_Thames, Riyadh, Roald_Amundsen, Roan_Antelope, Robert_Baden-Powell%2C_1st_Baron_Baden-Powell, Robert_Boyle, Robert_Gascoyne-Cecil%2C_3rd_Marquess_of_Salisbury, Robert_Oppenheimer, Robert_Owen, Robert_Peel, Robert_Schumann, Robert_Stephenson, Robinson_Crusoe, Roche_limit, Rock_Bunting, Rock_of_Gibraltar, Rockall, Rococo, Roentgenium, Roman_Britain, Roman_Greece, Roman_Vishniac, Roman_law, Roman_road, Roman_villa, Romeo_and_Juliet, Romulus_Augustus, Ronald_Reagan, Rondane_National_Park, Rook_%28bird%29, Rosa_Parks, Rose-ringed_Parakeet, Rosemary, Rotterdam, Rowan_Williams, Royal_Air_Force, Royal_Dutch_Shell, Royal_Geographical_Society, Royal_Grammar_School_Worcester, Royal_Marines, Royal_National_Theatre, Rubidium, Rubik%27s_Cube, Rudolf_Vrba, Rudyard_Kipling, Rugby_World_Cup, Rule_of_St_Benedict, Rupee, Russian_Revolution_of_1917, Russian_constitutional_crisis_of_1993, Ruthenium, Rutherford_B._Hayes, Rutherfordium, Rwandan_Genocide, S%C3%A3o_Paulo, S%C3%A3o_Tom%C3%A9, S%C3%A3o_Tom%C3%A9_and_Pr%C3%ADncipe, S%C3%B8ren_Kierkegaard, S-mine, S._A._Andr%C3%A9e%27s_Arctic_balloon_expedition_of_1897, SD26, SR-71_Blackbird, Safflower, Saint-Pierre_and_Miquelon, Saint_Helena, Saint_Joan_%28play%29, Saint_Kitts_and_Nevis, Saint_Lawrence_Seaway, Saint_Lucia, Saint_Vincent_and_the_Grenadines, Sakurajima, Saladin, Salford, Salsa_music, Salt, Salt_Lake_City%2C_Utah, Saltasaurus, Salvador_Dal%C3%AD, Samantha_Smith, Samarium, Samoa, Samuel_Beckett, Samuel_Taylor_Coleridge, San_Diegan, San_Diego_Electric_Railway, San_Francisco%2C_California, San_Francisco_garter_snake, San_Jose%2C_California, San_Marino, Sand_art_and_play, Sand_shark, Sandringham_House, Sandur, Sandy_Koufax, Sanssouci, Santa_Claus, Santamar%C3%ADa_%28volcano%29, Santiago%2C_Chile, Santorini, Sarajevo, Sardar_Vallabhbhai_Patel, Sasha_%28DJ%29, Saturn, Saturn_V, Saudi_Arabia, Sauropodomorpha, Sauroposeidon, Sauropsid, Saxicola, Saxophone, Scandium, Scanian_%28linguistics%29, Scattered_disc, Scelidosaurus, Scent_of_a_Woman, Schatzki_ring, Scheme_programming_language, Schizophrenia, Schr%C3%B6dinger_equation, Schuttern_Gospels, Scooby-Doo, Scotch_College%2C_Perth, Scotland_in_the_High_Middle_Ages, Scots_language, Scott_Special, Scottish_Episcopal_Church, Scottish_Highlands, Scottish_mythology, Scramble_for_Africa, Scrooge_McDuck, Scurvy, Sea_level_rise, Sea_of_Galilee, Seaborgium, Sean_Connery, Sears_Catalog_Home, Seattle%2C_Washington, Second_Boer_War, Second_Congo_War, Second_Crusade, Seinfeld, Selena, Selenium, Semiconductor_device, Senate_of_Canada, Senufo_languages, Seoul, Separation_of_powers_under_the_United_States_Constitution, September_11%2C_2001_attacks, Sequoia, Serbia_and_Montenegro, Serenity_%28film%29, Sermon_on_the_Mount, Sesame, Sesame_Street, Severn_crossing, Sgt._Pepper%27s_Lonely_Hearts_Club_Band, Shabo_language, Shackleton_%28crater%29, Shaka, Sharon_Tate, Sheffield, Sheikh_Mujibur_Rahman, Shelduck, Shenzhou_6, Shenzhou_spacecraft, Shetland, Shielded_metal_arc_welding, Shigin, Shining_Path, Shinto, Shoe_polish, Short-beaked_Echidna, Shoshone_National_Forest, Shrimp_farm, Shrine_of_Remembrance, Shroud_of_Turin, Sichuan_Pepper, Sicilian_Baroque, Siege_of_Antioch, Sigmund_Freud, Sikhism, Sikkim, Silurian, Silver, Sim%C3%B3n_Bol%C3%ADvar, SimCity, Simca_Vedette, Sinclair_Research_Ltd, Sino-German_cooperation_%281911-1941%29, Sino-Roman_relations, Sirius, Sistine_Chapel_ceiling, Six-party_talks_concerning_North_Korea%27s_nuclear_program, Sk%C3%A5neland, Ska, Skiing, Skylark, Slavic_mythology, Sleep, Slovakia, Slovenia, Smog, Snaefell_Mountain_Railway, Snake_charming, Snow_Goose, Snowball_Earth, Snowdonia_National_Park, Snowy_Owl, Social_anxiety, Social_capital, Social_contract_%28Malaysia%29, Society_of_Merchant_Venturers, Sociocultural_evolution, Socrates, Soddo_language, Sodium_hydroxide, Sodium_sulfate, Soil_moisture, Soil_pH, Soil_salination, Soil_science, Soil_structure, Solar_eclipse, Song_Thrush, Sonic_the_Hedgehog_%28character%29, Sorghum, Sorrel, Soukous, Soup, South_Georgia_and_the_South_Sandwich_Islands, South_Ossetia, Southampton, Southern_Pacific_4449, Southern_Rockhopper_Penguin, Soybean, Space_Invaders, Space_Race, Space_Shuttle_Challenger_disaster, Space_Shuttle_Endeavour, Space_Shuttle_program, Space_station, Space_suit, Spacecraft_propulsion, Spanish_Armada, Spanish_Inquisition, Spanish_conquest_of_the_Inca_Empire, Sparrowhawk, Speaker_of_the_British_House_of_Commons, Speaker_of_the_United_States_House_of_Representatives, Special_relativity, Sperm_Whale, Spherical_aberration, Spinosaurus, Spirit_of_the_American_Doughboy, Spix%27s_Macaw, Split_infinitive, Sponsorship_Directdebit, Spotted_Flycatcher, Spring_%28season%29, Spring_Heeled_Jack, Sputnik_1, Sputnik_2, Sputnik_program, Spyware, Squash_%28sport%29, Sri_Lankan_Civil_War, St_Buryan, St_Michael%27s_Mount, St_Paul%27s_Cathedral, Stag_beetle, Stage_%28theatre%29, Stained_glass, Stanis%C5%82aw_Koniecpolski, Stanis%C5%82aw_Lem, Stanley%2C_Falkland_Islands, Stanley_Baldwin, StarCraft, Star_Fox__Assault, Star_Trek__Deep_Space_Nine, Star_Trek__The_Original_Series, Star_anise, Stargate_SG-1, Starling, Starship_Troopers, Statistics, Statue_of_Zeus_at_Olympia, Stefan_Edberg, Stegosaurus, Stem_cell, Stephen_Harper, Stephen_Hawking, Stephen_Jay_Gould, Stephen_Trigg, Steve_Davis, Stickleback, Still_Game, Stingray, Stock, Stock_car_%28rail%29, Stockholm, Stone_Age, Stonehenge, Storm_of_October_1804, Stornoway, Stourbridge_Lion, Strait_of_Malacca, Stratford-upon-Avon, String_theory, Strontium, Struthiomimus, Stuttering, Stuttgart, Styracosaurus, Sub-Saharan_Africa, Suburbs_of_Johannesburg, Sucre, Sudanic_languages, Sudoku, Suez_Canal, Suffrage, Sugar_beet, Suikinkutsu, Suleiman_the_Magnificent, Sulfur, Sulfuric_acid, Sumac, Summer_Hill%2C_New_South_Wales, Sumo, Sun_Tzu, Sun_Yat-sen, Sunflower, Sunol_Water_Temple, Sunset_Boulevard_%281950_film%29, Super_14, Super_Bowl_XL, Super_Chief, Super_Mario_64, Super_Mario_Bros., Superconductivity, Supply_chain_management, Supreme_Court_of_the_United_States, Suriname, Surtsey, Sustainable_forestry, Sutton_Hoo, Svalbard, Svart%C3%A1lfar, Swallow, Swan, Swastika, Swaziland, Swedish_allotment_system, Swift, Swiss_Federal_Council, Swissair_Flight_111, Sydney_Newman, Sydney_Riot_of_1879, Sylvanus_Morley, T-34, T._D._Judah, T._S._Eliot, TGV, Tacitean_studies, Tagoi_language, Taipei, Taj_Mahal, Tajikistan, Talc, Tamarind, Tamil_language, Tansy, Tao_Te_Ching, Tarragon, Tashkent, Tasmanian_Devil, Tawny_Owl, Tay-Sachs_disease, Tay_Rail_Bridge, Technetium, Tehran, Tel_Aviv, Telephone, Telephone_exchange, Tellurium, Temple_of_Artemis, Templon, Tennis_Masters_Cup, Tenzin_Gyatso%2C_14th_Dalai_Lama, Tenzing_Norgay, Terbium, Terik, Terrorism, Thalassemia, The_Absent-Minded_Beggar, The_Adventures_of_Tintin, The_Anarchy, The_Ashes, The_Beano, The_Beatles_discography, The_Blitz, The_Broads, The_Brothers_Karamazov, The_Canadian, The_Cantos, The_Cat_in_the_Hat, The_Catcher_in_the_Rye, The_Catlins, The_Championships%2C_Wimbledon, The_Children%27s_Machine, The_Count_of_Monte_Cristo, The_Country_Wife, The_Curious_Incident_of_the_Dog_in_the_Night-time, The_Dandy, The_Fairy-Queen, The_Famous_Five_%28characters%29, The_Fens, The_Frogs, The_Gambia, The_Godfather, The_Great_Exhibition, The_Hague, The_Hitchhiker%27s_Guide_to_the_Galaxy, The_Hobbit, The_Holocaust, The_Illuminatus%21_Trilogy, The_Importance_of_Being_Earnest, The_Iron_Bridge, The_King%27s_Regiment_%28Liverpool%29, The_Last_Supper_%28Leonardo%29, The_Legend_of_Zelda_series, The_Lion%2C_the_Witch_and_the_Wardrobe, The_Lorax, The_Lord_of_the_Rings_film_trilogy, The_Magic_Flute, The_Marriage_of_Figaro, The_Merchant_of_Venice, The_Mismeasure_of_Man, The_Old_Man_and_the_Sea, The_Origin_of_Species, The_Oz_books, The_Picture_of_Dorian_Gray, The_Pilgrim%27s_Progress, The_Quatermass_Experiment, The_Relapse, The_Rime_of_the_Ancient_Mariner, The_Rite_of_Spring, The_Rolling_Stones, The_Seagull, The_Shawshank_Redemption, The_Simpsons, The_Smiths, The_Temptations, The_Wall_Street_Journal, The_Waste_Land, The_West_Wing_%28TV_series%29, The_X-Files, Theatre_Royal%2C_Drury_Lane, Theatre_in_the_round, 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F4 has size 200; articles in F4 but not in F5: [15th_century, Animal, Animation, Austria, Bulgaria, C%25C3%25B4te_d%2527Ivoire, Chemical_element, Church_of_England, Citizenship, City_status_in_the_United_Kingdom, Civilization, Color, Convention_on_the_Rights_of_the_Child, Crystal, Currency, East_Africa, Evolution, Genetics, Geography, Gravitation, Great_Britain, Guinea-Bissau, History, Hubble_Space_Telescope, International_law, Internet, Iraq, Islam, Language, Latin, Liberal_democracy, Light, Mathematics, Matter, Microsoft, Middle_Ages, Music, Netherlands, North_America, Pacific_Ocean, Plant, Richard_I_of_England, Triassic]
F5 has size 157; articles in F5 but not in F6: [5th_century, Africa, Art, British_monarchy, Chemistry, Computer, Cyprus, Electromagnetic_radiation, Germany, International_human_rights_instruments, Money, Permian, Physics, Property, Quantity, Rome, The_Lion_King, Treaty_of_Versailles]
F6 has size 139; articles in F6 but not in F7: [19th_century, Adam_Smith, Anno_Domini, Barley, Capital, Continent, Human_rights, Mediterranean_Sea, United_States, Watch, Wave, World_War_I]
F7 has size 127; articles in F7 but not in F8: [Cereal, Clock, Country, Energy, Jesus, Nationality, Ottoman_Empire, Politics, Scotland, Sea, War]
F8 has size 116; articles in F8 but not in F9: [16th_century, Agriculture, Aristotle, Government, Ocean, United_Kingdom]
F9 has size 110; articles in F9 but not in F10: [Ancient_Greece, Corporation, Food, Seawater, Time]
F10 has size 105; articles in F10 but not in F11: [Christianity, Employment, Isaac_Newton, Water]
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F13 has size 94; articles in F13 but not in F14: [Biology, Earth]
F14 has size 92; articles in F14 but not in F15: [Planet]
F15 has size 91; articles in F15 but not in F16: [Solar_System]
F16 has size 90; articles in F16 but not in F17: [Sun]
F17 has size 89; articles in F17 but not in F18: [Star]
F18 has size 88; articles in F18 but not in F19: []

The 38 cycles:
[Culture, Anthropology, Human, Mammal, Vertebrate, Cambrian_explosion, Fossil, Mineral, Geology, Science, Society]
[Economics, Education, Family, Sociology, Globalization]
[Iran, Persian_Empire]
[United_States_House_of_Representatives, United_States_Congress]
[Cotton, Textile]
[Mustard_plant, Mustard_seed]
[Communication, Information]
[Homer, Odyssey]
[Boat, Ship]
[Universe, Cosmic_inflation]
[Soil, Soil_profile]
[Screw, Wrench]
[Actor, Drama]
[ITunes, IPod]
[Abhidhamma_Pitaka, Pali_Canon]
[Philosophy, Logic]
[Latvia, Estonia]
[Protein, Genetic_code]
[Space_Shuttle_Columbia_disaster, Space_Shuttle_Columbia]
[Whale, Dolphin]
[Tuatara, Reptile]
[Wood, Tree]
[Gull, Tern]
[Optical_telescope, Telescope]
[GNU_Project, Richard_Stallman]
[Mind, Emotion]
[Fiction, Novel]
[Black_Wildebeest, Wildebeest]
[Chimpanzee, Bonobo]
[Fossil_fuel, Coal]
[Kangaroo, Wallaby]
[Sweden, Norway]
[Meander, Oxbow_lake]
[Electric_charge, Electron]
[Cambrian, Ordovician]
[ABO_blood_group_system, Blood_type]
[Opera, Theatre]
[Real_tennis, Tennis]
```