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, Alberto_Santos-Dumont, Albertosaurus, Albigensian_Crusade, Albinism, Albrecht_D%C3%BCrer, Albrecht_Rodenbach, Alchemy, Alcibiades, Aleksandr_Pushkin, Aleksandr_Vasilevsky, Aleksey_Arakcheyev, Alexander_Graham_Bell, Alexander_Hamilton, Alexander_the_Great, Alfred_Hitchcock, Alfred_Nobel, Alfred_the_Great, Algerian_Civil_War, Algiers, Algol, Algoma_Central_Railway, Alice%27s_Adventures_in_Wonderland, All_Blacks, All_You_Need_Is_Love_%28The_JAMs_song%29, All_your_base_are_belong_to_us, Allah, Allegory_in_the_Middle_Ages, Alligator, Alliterative_verse, Allosaurus, Almaty, Almond, Alpaca, Alternation_of_generations, Alternative_rock, Aluminium_chloride, Alzheimer%27s_disease, Amaranth_oil, Amarillo%2C_Texas, Amazon_Rainforest, Amazon_parrot, Amber, Amda_Seyon_I, American_English, American_Samoa, Americium, Amish, Ammolite, Ammonite, Ammosaurus, Amur, Anaconda, Analytical_Marxism, Anarchism, Anarcho-capitalism, Andorra, Andr%C3%A9s_Nocioni, Andrew_Carnegie, Andrew_Dickson_White, Andrew_Gonzalez, Andrew_Jackson, Andrew_Johnson, Andrew_Robinson, Andriyivskyy_Descent, Andromeda_Galaxy, Andy_Warhol, Angel_shark, Angelica, Angkor_Wat, Anglican_Church_of_Australia, Anglicanism, Anglo-Saxon_literature, Angola, Anguilla, Animal_rights, Ankylosaurus, Ann_Arbor%2C_Michigan, Anna_Karenina, Anne_Frank, Annibale_Bugnini, Anschluss, Antananarivo, Antarctic_Treaty_System, Antarctic_krill, Antarctosaurus, Anteater, Anthony_van_Dyck, Antimony, Antlion, Antoine_Lavoisier, Anton%C3%ADn_Dvo%C5%99%C3%A1k, Anton_Alexander_von_Werner, Antonio_Vivaldi, Apaochi, Apatosaurus, Aphid, Apollo, Apollo_8, Apple, Apricot, Arab-Israeli_conflict, Arab_League, Arable_land, Aradia%2C_or_the_Gospel_of_the_Witches, Aral_Sea, Arcadia_%28play%29, Archaeoastronomy, Archaeopteryx, Archimedes, Architecture, Architecture_of_Windows_NT, Architecture_of_the_California_missions, Arctic_Circle, Arctic_Monkeys, Arctic_Tern, Argan, Argon, Argyle_diamond_mine, Ariel_Sharon, Aristarchus_%28crater%29, Arithmetic, Armadillo, Armand_Jean_du_Plessis%2C_Cardinal_Richelieu, Armia_Krajowa, Arnold_Schwarzenegger, Arp2_3_complex, Ars_moriendi, Arsenal_F.C., Arsenic, Arthur_Ernest_Percival, Arthur_Sullivan, Arthur_Upfield, Arthur_Wellesley%2C_1st_Duke_of_Wellington, Arts_and_crafts, Aruba, Arugula, Ascariasis, Asp_%28reptile%29, Asparagus, Asperger_syndrome, Assyria, Astatine, Asthma, Astrophysics_Data_System, Asunci%C3%B3n, Ateneo_de_Manila_University, Athanasius_Kircher, Athletics_%28track_and_field%29, Atlanta%2C_Georgia, Atlantic_Coast_Line_Railroad, Atlantic_herring, Atlantis, Atonality, Attack_on_Pearl_Harbor, Attention-deficit_hyperactivity_disorder, Attila_the_Hun, Auckland, Augusta%2C_Lady_Gregory, Augustan_literature, Auguste_Rodin, Augustine_of_Hippo, Augustus, Australian_Green_Tree_Frog, Australian_Ringneck, Australian_constitutional_law, Australian_rules_football, Autobianchi_Primula, Automated_teller_machine, Automatic_number_plate_recognition, Autorack, Autostereogram, Autumn, Avacha_Volcano, Avalanche, Avatar__The_Last_Airbender, Avocado, Avro_Lancaster, Axe, Ayaan_Hirsi_Ali, Aye-aye, Aymer_de_Valence%2C_2nd_Earl_of_Pembroke, Azerbaijani_people, Aztec, BAE_Systems, BASIC, BBC_television_drama, BP, BT_Tower, B_vitamins, Babe_Ruth, Baboon, Babur, Baby_Gender_Mentor, Backgammon, Baden-Powell_House, Badger, Badminton, Badugi, Bah%C3%A1%27%C3%AD_Faith, Bahamas, Bahrain, Baker_Island, Bald_Eagle, Baltimore%2C_Maryland, Bamako, Bandicoot, Bangalore, Bangkok, Banjul, Bank_of_China_%28Hong_Kong%29, Banknote, Banksy, Bantu, Barack_Obama, Barbados, Barbara_McClintock, Barbary_Lion, Barbary_Macaque, Barcelona, Barium, Barn_Owl, Barnacle, Barracuda, Baruch_Spinoza, Basel, Basil, Basil_Brush, Basilica_of_San_Francesco_d%27Assisi, Basilica_of_Santa_Maria_degli_Angeli, Basking_shark, Bass_%28fish%29, Basset_Hound, Bassoon, Bat-eared_Fox, Bath%2C_Somerset, Bath_School_disaster, Batholith, Batman, Battle_of_Alesia, Battle_of_Amiens, Battle_of_Austerlitz, Battle_of_Badr, Battle_of_Bicocca, Battle_of_Britain, Battle_of_Cannae, Battle_of_France, Battle_of_Gettysburg, Battle_of_Grunwald, Battle_of_Hastings, Battle_of_Jutland, Battle_of_Lechaeum, Battle_of_Leyte_Gulf, Battle_of_Marathon, Battle_of_Midway, Battle_of_Moscow, Battle_of_Normandy, Battle_of_Rennell_Island, Battle_of_Sitka, Battle_of_Smolensk_%281943%29, Battle_of_Stalingrad, Battle_of_Tours, Battle_of_Vaslui, Battle_of_Warsaw_%281920%29, Battle_of_the_Bulge, Battle_of_the_Eastern_Solomons, Battle_of_the_Little_Bighorn, Battle_of_the_Santa_Cruz_Islands, Battle_of_the_Somme_%281916%29, Battles_of_the_Mexican-American_War, Bay_Area_Rapid_Transit, Beach, Bear, Beatles_for_Sale, Beaver, Bedbug, Bede, Beeching_Axe, Beekeeping, Beep_%28SWBLW%29, Beer, Beet, Behavioral_finance, Behistun_Inscription, Beirut, Belize, Belton_House, Ben-Hur_%281959_film%29, Ben_Jonson, Ben_Nevis, Bench_language, Benito_Mussolini, Benjamin_Britten, Benjamin_Disraeli%2C_1st_Earl_of_Beaconsfield, Benjamin_Franklin, Benjamin_Harrison, Benjamin_Mountfort, Benjamin_of_Tudela, Berber_languages, Beriberi, Berkelium, Berlin_Wall, Bermuda, Bernard_Hinault, Bertrand_Russell, Beryllium, Betelgeuse_incident, Bette_Davis, Bhutan, Bicycle, Bicycle_Thieves, Bill_Clinton, Bill_Gates, Billie_Holiday, Binoculars, Biodiesel, Biodiversity, Biofuel, Bionicle__Mask_of_Light, Biosphere, Biotechnology, Birmingham, Birth_control, Bismuth, Bison, Bissau, Bj%C3%B6rn_Borg, Bj%C3%B8rn%C3%B8ya, Black-backed_Jackal, Black-footed_Cat, Black-winged_Stilt, Black_Death, Black_Rhinoceros, Black_Robin, Black_Seminoles, Black_hole, Black_panther, Black_widow_spider, Blackbird, Blackjack, Blackpool, Blacktip_reef_shark, Blade_Runner, Blaise_Pascal, Blitzkrieg, Blokus, Blue_Peter, Blue_Tit, Blue_Whale, Blue_Wildebeest, Blue_shark, Bluegrass_music, Bluetooth, Bob_Dylan, Bob_Marley, Bobcat, Body_mass_index, Bodyline, Boeing_747, Bog, Bogot%C3%A1, Bohemian_Rhapsody, Bohor_Reedbuck, Bohrium, Bolivia, Bologna, Boltysh_crater, Bongo_%28antelope%29, Bontebok, Booby, Book_of_Common_Prayer, Book_of_Kells, Boolean_logic, Borage, Boris_Becker, Boron, Boston%2C_Massachusetts, Boston_RFC, Boston_Terrier, Boston_and_Lowell_Railroad, Botswana, Bottlenose_Dolphin, Boudica, Boundary_Waters_Canoe_Area_Wilderness, Bourbonnais_train_accident, Bouvet_Island, Box_jellyfish, Boyle_Roche, Brabantian, Brabham, Brachiosaurus, Bran, Brandon_Routh, Bras%C3%ADlia, Bratislava, Bread, Breaker_Morant, Bretton_Woods_system, Brian_Close, Brighton, Brisbane, British_East_India_Company, British_Indian_Ocean_Territory, British_Isles_%28terminology%29, British_Virgin_Islands, Britney_Spears, Bromine, Brothers_Grimm, Brown_trout, Bruce_Lee, Bruce_Springsteen, Brunei, Brute_force_attack, Bryce_Canyon_National_Park, Btrieve, Bucharest, Buckingham_Palace, Buckminster_Fuller, Budapest, Buddhist_art, Buenos_Aires, Bull_shark, Burkina_Faso, Burundi, Bushbuck, Bushpig, Butter, Button, Byzantine_Empire, C%2B%2B, C%C3%A6dmon, C%C3%B4te_d%27Ivoire, CPU_cache, CS_gas, Cadmium, Caesium_fluoride, Cai_Lun, Calcite, Calgary, California_Southern_Railroad, Californium, Calligraphy, Caloris_Basin, Calvin_Coolidge, Calvin_and_Hobbes, Camarasaurus, Cambodia, Camel, Cameroon, Canada_Goose, Canadian_Charter_of_Rights_and_Freedoms, Canadian_English, Canadian_House_of_Commons, Canadian_Senate, Canadian_football, Canaletto, Cane_Toad, Canola, Canterbury, Canterbury_Cathedral, Canute_the_Great, Capacitance, Cape_Canaveral, Cape_Horn, Cape_Lion, Cape_Porcupine, Cape_Town, Cape_Verde, Capitalism, Capitoline_Triad, Captain_Marvel_%28DC_Comics%29, Caracas, Caratacus, Caravaggio, Carcinus_maenas, Cardiff, Carl_Friedrich_Gauss, Carl_G._Fisher, Carl_Jung, Carl_Lewis, Carl_Sagan, Carlsbad_Caverns_National_Park, Caroline_Island, Carolingian_Gospel_Book_%28British_Library%2C_MS_Add._11848%29, Carolus_Linnaeus, Casablanca_%28film%29, Casimir_effect, Cassini-Huygens, Cassowary, Castra, Cat%27s_Eye_Nebula, Cat_Stevens, Cataract_surgery, 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, Crimson-collared_Tanager, Cristero_War, Criticism_of_the_War_on_Terrorism, Croatia, Crocodile, Crohn%27s_disease, Cross_Fell, Crossbill, Crown_Jewels_of_the_United_Kingdom, Crust_%28geology%29, Crystallographic_defects_in_diamond, Cubeb, Cubism, Cuckmere_Haven, Cultural_diversity, Cultural_identity, Culture_of_the_Democratic_Republic_of_the_Congo, Curium, Cyanocobalamin, Cyberpunk, Cyclamen, Cyclone_Percy, Cyclone_Rosita, Cyclops, Cymbopogon, Cyril_Clarke, Cyrus_K._Holliday, Cyrus_the_Great, Cystic_fibrosis, Czech_Republic, D%C3%A1l_Riata, D%C3%BCsseldorf, DNA_repair, DVD, Dad%27s_Army, Dada, Dakar, Dakota%2C_Minnesota_and_Eastern_Railroad, Daley_Thompson, Dallas%2C_Texas, Damascus, Damascus_steel, Damon_Hill, Daniel_Day-Lewis, Daniel_Ellsberg, Danny_Deever, Danske_Statsbaner, Dante_Alighieri, Danube, Darfur_conflict, Dark_Ages, Darling_River, Darmstadtium, Darth_Vader, Dartmoor, Das_Kapital, Data_Encryption_Standard, David_Attenborough, David_Beckham, David_Blanchflower, David_Cameron, David_Copperfield_%28novel%29, David_Helvarg, David_Heymann, David_Hilbert, David_Hume, David_III_of_Tao, Davis_Cup, Davy_Jones%27_Locker, Day, Dayuan, Dead_Sea, Dead_Sea_scrolls, Death_Valley_National_Park, Decade_Volcanoes, Deconstructivism, Defaka, Defense_of_Sihang_Warehouse, Definition_of_planet, Deinonychus, Deluge_%28mythology%29, Demand_Note, Democratic_Action_Party, Demosthenes, Denis_Law, Dennis_Ritchie, Denver%2C_Colorado, Derby, Desert_locust, Desmond_Tutu, Despotism, Detroit%2C_Michigan, Dewey_Square, Diamond_cut, Diamond_simulant, Dice, Dido_and_Aeneas, Diego_Garcia, Diego_Maradona, Diego_Vel%C3%A1zquez, Differential_equation, Differential_geometry_and_topology, Diffuse_interstellar_band, Dik-dik, Dill, Dilophosaurus, Dimetrodon, Dingo, Diplodocus, Directdebit, Directive_Principles_in_India, Disneyland_Railroad, Distilled_beverage, Dixie_Mission, Djibouti, Dmitri_Mendeleev, Doctor_Who, Dodo, Doha, Domesday_Book, Domestic_AC_power_plugs_and_sockets, Domestic_goat, Domesticated_turkey, Dominican_Republic, Donald_Knuth, Donation, Doom, Double-decker_bus, Douglas_DC-4, Draughts, Driving_on_the_left_or_right, Drosera_anglica, Drosophila_melanogaster, Drum_and_bass, Du_Fu, Dualism_%28philosophy_of_mind%29, Dubai, Dubnium, Duchenne_muscular_dystrophy, Dundee, Dundee_United_F.C., Dune, Dunnock, Dunstable_Downs, Duran_Duran, Durham_Cathedral, Durian, Dwight_D._Eisenhower, Dysprosium, E.T._the_Extra-Terrestrial_%28Atari_2600%29, E._E._Cummings, E._P._Wigner, ECHELON, EMD_BL2, EMD_F7, EMD_GP30, Eagle_Scout_%28Boy_Scouts_of_America%29, Earl_of_Shaftesbury, Earless_seal, Earth%27s_atmosphere, Earwax, East-West_Schism, EastEnders, East_Flemish, East_Timor, Easter_Island, Eastern_Orthodox_Church, Eastern_Roman_Empire, Ebony, Economic_inequality, Economy_of_Africa, Economy_of_India, Economy_of_Pakistan, Economy_of_Scotland, Economy_of_the_Iroquois, Economy_of_the_Republic_of_Ireland, Ecuador, Edema, Edgar_Allan_Poe, Edible_salt, Edinburgh, 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, Extinct_birds, Eye_%28cyclone%29, 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Floris_and_Blancheflour, Floyd_Mayweather_Jr., Fluorine, Flute, Foie_gras, Football_%28soccer%29, Forensic_facial_reconstruction, Formic_acid, Forrest_Gump, Fort_de_Chartres, Forth, Forth_Bridge_%28railway%29, Forth_Road_Bridge, Fossil_record, Fr%C3%A9d%C3%A9ric_Chopin, Fractal, France_in_the_American_Revolutionary_War, Frances_Oldham_Kelsey, Francis_Bacon, Francis_Crick, Francis_Drake, Francis_Petre, Francisco_Goya, Francium, Frank_Lloyd_Wright, Frankenstein, Franklin_B._Gowen, Franklin_D._Roosevelt, Franklin_Pierce, Franz_Kafka, Franz_Schubert, Frederick_Douglass, Frederick_Hamilton-Temple-Blackwood%2C_1st_Marquess_of_Dufferin_and_Ava, Frederick_II%2C_Holy_Roman_Emperor, Frederick_II_of_Prussia, Freetown, French_Guiana, French_Open_%28tennis%29, French_Polynesia, French_Southern_and_Antarctic_Lands, Friedrich_Nietzsche, Friend_Directdebit, Fugu, Full_moon, Funchal, Fundamental_Rights_in_India, Fundamental_theorem_of_arithmetic, Fungus, Fur_language, Fusarium, Fyodor_Dostoevsky, GDRT, GNU_Linux_naming_controversy, Gaborone, Gadolinium, Gal%C3%A1pagos_Islands, Galah, Galeras, Galerina, Galileo_Galilei, Gallery_of_the_Kings_and_Queens_of_England, Gallimimus, Gallium, Galveston_Hurricane_of_1900, Ganesha, Ganges_shark, Gangtok, Garage_%28dance_music%29, Garden_Gnome_Liberation_Front, Gardening, Gas_giant, Gas_metal_arc_welding, Gas_tungsten_arc_welding, Gas_turbine-electric_locomotive, Gauss%27s_law, Gaza_Strip, Gazelle, Gender, Genealogy, General_Pershing_Zephyr, Genoa, Gentoo_penguin, Geography_of_Africa, Geography_of_India, Geography_of_Ireland, Geography_of_Texas, Geology_of_Dorset, Geology_of_the_Grand_Canyon_area, Georg_Cantor, Georg_Forster, Georg_von_Boeselager, George_Byron%2C_6th_Baron_Byron, George_Eliot, George_Fox, George_H._W._Bush, George_Herbert, George_II_of_Great_Britain, George_IV_of_the_United_Kingdom, George_I_of_Great_Britain, George_Thomas_Coker, George_VI_of_the_United_Kingdom, George_V_of_the_United_Kingdom, 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, Grand_Forks%2C_North_Dakota, 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Heraclius, Heraldry, Herbert_Hoover, Herbig-Haro_object, Hermann_Maier, Hern%C3%A1n_Cort%C3%A9s, Hero_of_Ukraine, Hero_of_the_Russian_Federation, Herodotus, Heron, Herrerasaurus, Herring_Gull, Hey_Jude, Hickman%27s_potentilla, High_German_consonant_shift, Hilda_of_Whitby, Himno_Nacional_Mexicano, Hindi, Hippocrates, Hiroh_Kikai, Hirohito, History_of_Alaska, History_of_Anglo-Saxon_England, History_of_Arizona, History_of_Buddhism, History_of_Burnside, History_of_Cape_Colony_from_1806_to_1870, History_of_Cape_Colony_from_1870_to_1899, History_of_Central_Asia, History_of_Earth, History_of_Greece, History_of_Greenland, History_of_Limerick, History_of_Louisville%2C_Kentucky, History_of_Miami%2C_Florida, History_of_New_Jersey, History_of_Northwest_Territories_capital_cities, History_of_Poland_%281945%E2%80%931989%29, History_of_Portugal_%281777%E2%80%931834%29, History_of_Puerto_Rico, History_of_Russia, History_of_Singapore, 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, Magellanic_Penguin, Maghreb, Maglev_train, Magna_Carta, Magnesium, Magnet, Magnetism, Magpie, Mahabharata, Mahjong, Mahmoud_Abbas, Maiasaura, Maize, Makuria, Malaria, Malaspina_Glacier, Malawi, Malcolm_III_of_Scotland, Malcolm_X, Maldives, Malta, Malwa_%28Madhya_Pradesh%29, Mamenchisaurus, Mammoth, Mammoth_Cave_National_Park, Mancala, Manchester, Mandan, Manganese, Mango, Manifest_Destiny, Manifold, Manorialism, Manuel_I_Komnenos, Mao_Zedong, Map_projection, Maputo, Marc_Pugh, Marcel_Lefebvre, Marcel_Proust, Marco_Polo, Marcus_Allen, Margaret_Sanger, Margaret_Thatcher, Margate, Margin_of_error, Marginated_Tortoise, Marie_Curie, Mario, Marjoram, Mark_Twain_House, Mark_Webber, Markup_language, Mars_Exploration_Rover, Mars_Reconnaissance_Orbiter, Marseille, Marshall_Islands, Marshall_Plan, Martello_tower, Martin_Luther, Martin_Luther_King%2C_Jr., Martin_Van_Buren, Martina_Navratilova, Marvin_Gaye, Mary_II_of_England, Mary_I_of_England, Mary_I_of_Scotland, Mary_Kingsley, Mary_Seacole, 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, 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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, 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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, Theodore_Roosevelt, Therizinosaurus, Thermodynamic_temperature, Theta, Thiamine, Third_Servile_War, Thomas_Becket, Thomas_Cranmer, Thomas_Gainsborough, Thomas_Hobbes, Thomas_Jefferson, Thomas_Malthus, Thomas_More, Thomas_Pynchon, Thomas_Samuel_Kuhn, Thor, Thorax, Thorium, Thrasybulus, Three_Gorges_Dam, Three_Laws_of_Robotics, Three_Mile_Island_accident, Thrush_%28bird%29, Thulium, Thunderstorm, Tiananmen_Square_protests_of_1989, Tide, Tiger_Woods, Tiger_shark, Tijuana, Tiktaalik, Tim_Berners-Lee, Tim_Henman, Timbuktu, Time_zone, Timeline_of_discovery_of_solar_system_planets_and_their_natural_satellites, Timken_1111, Timur, Tin, Tin%28II%29_chloride, Tin_whistle, Tiridates_I_of_Armenia, Titanosauridae, To_Kill_a_Mockingbird, Tobacco_smoking, Tofu, Tokelau, Toluene, Tom_and_Jerry_%28MGM%29, Tone_cluster, Tonga, Tony_Blair, Tooth_development, Tooth_enamel, Topology, Toraja, Tottenham_Hotspur_F.C., Tour_de_France, Tourette_syndrome, Tourism, Tower_Bridge, Tower_of_London, Toy_Story, 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Saint_Petersburg, San_Diego_and_Arizona_Railway, San_Francisco%252C_California, Sand, Sassanid_Empire, Scottish_Gaelic_language, Seattle%252C_Washington, Senegal, September_11%252C_2001_attacks, Sequence_alignment, Serbia, Set, Seychelles, Shanghai, Shark, Sickle-cell_disease, Siege, Silent_film, Sim%25C3%25B3n_Bol%25C3%25ADvar, Singapore, Sitting_Bull, Smallpox, Snowdonia, Sodium, Soils_retrogression_and_degradation, Solomon_Islands, South_Korea, Southern_Ocean, Soviet_Union, Space_Shuttle_Challenger, Spanish_language, Sparrow, Speed_of_light, Sphere, Spider, Star_Trek, Star_Wars, Steam_engine, Steel, Stephen_of_England, Stoicism, Stroke, Sudan, Sugarcane, Sumatra, Summer, Sundew, Sunlight, Superman, Supermarine_Spitfire, Supply_and_demand, Sydney, Symmetry, Synthesizer, Taiwan, Tamil_people, Tank, Tantalum, Tanzania, Taoism, TeX, Tea, Technology, Thailand, Thallium, The_Bahamas, The_Beatles, The_Lord_of_the_Rings, The_Supremes, Thermodynamics, Theropoda, Thomas_Aquinas, Thomas_Edison, Thucydides, Tibet, Tiger, Tigris, Titanium, Tobacco, Tokyo, Top_of_the_Pops, Tornado, Toronto, Trade_union, Train, Tree_frog, Tribe, Trinidad_and_Tobago, Trinity, Tungsten, Tunisia, Turin, Tutsi, Tycho_Brahe, Uganda, Ultraviolet, United_Arab_Emirates, United_States_Senate, University, University_of_Cambridge, Uruguay, Vegetable, Venezuela, Victoria_of_the_United_Kingdom, Vietnam, Vietnam_War, Viking, Virgil, Virus, Visual_arts, Vitamin_C, Vitus_Bering, Volcano, Vowel, War_of_the_League_of_Cambrai, Washington%252C_D.C., Water_Buffalo, Weimar_Republic, Welding, Wernher_von_Braun, Wessex, West_Bank, West_Virginia, Western_Sahara, Wikimedia_Foundation, William_III_of_England, William_IV_of_the_United_Kingdom, William_I_of_England, William_Shakespeare, Windows_Vista, Wine, Wolfgang_Amadeus_Mozart, Woodpecker, World_Heritage_Site, Writing, X_Window_System, Xenon, Yangtze_River, York, Yttrium, Z%25C3%25BCrich, ZX_Spectrum, Zambezi, Zambia, Zebra, Zhang_Qian, Zinc, Zulu] F2 has size 490; articles in F2 but not in F3: [17th_century, 18th_century, 4-4-0, 6th_century, 8th_century, 9th_century, Action_potential, Age_of_Enlightenment, Airbus, Aircraft, Alcohol, Algeria, Aluminium, Alzheimer%2527s_disease, American_Revolutionary_War, American_popular_music, Anatomy, Andes, Antarctica, Archaeology, Arctic, Arecaceae, Arthropod, Atom, Australia, Australian_English, Auto_racing, Babylonia, Bacteria, Baltic_Sea, Baroque, Bioinformatics, Bird_of_prey, Black_Sea, Blackcap, Board_game, Brain, Bridge, Bristol, British_Isles, Broadcasting, Brush, Brussels, Buddhism, Calcium, Cambridge, Canada, Cancer, Carbon, Caribbean_Sea, Carnivore, Caspian_Sea, Charles_I_of_England, Charles_V%252C_Holy_Roman_Emperor, Citrus, City, Civil_rights, Comics, Communism, Computer_programming, Cretaceous, Cryptography, Dallas%252C_Texas, Deity, Desert, Devonian, Earthquake, Electricity, Emirate, English_Channel, Ethnic_group, Euclid, European_Union, Fire, Fish, Flanders, Flower, French_Revolution, French_language, Frog, Fruit, Gal%25C3%25A1pagos_Islands, Glacier, Granite, Greek_mythology, Hebrew_language, Henry_III_of_England, Henry_II_of_England, Henry_VII_of_England, Herbivore, Himalayas, Honduras, Horse, Imperative_programming, Indian_Ocean, Indian_independence_movement, Indonesia, Industry, Insect, Invasion, Irish_Sea, Italian_Renaissance, Italy, Jerusalem, Jordan_River, Judaism, Karl_Marx, Kazakhstan, Landform, Laos, Libya, Linux, List_of_monarchs_in_the_British_Isles, Liverpool_and_Manchester_Railway, London, Manila, Market, Mechanical_work, Metal, Microsoft_Windows, Milky_Way, Mississippi_River, Mona_Lisa, Monarchy, Mongol_Empire, Montenegro, Moon, Nature, Neutron, Nintendo, Nitrogen, North_Korea, Old_English_language, Oligarchy, Oligocene, Oxygen, Pakistan, Papua_New_Guinea, Parliament_of_the_United_Kingdom, People%2527s_Republic_of_China, Peru, Piano, Plate_tectonics, Podcasting, Political_philosophy, Pope, Portugal, Psychology, Radio, Rail_transport, Republic_of_China, Republic_of_Ireland, Rhythm_and_blues, Rock_Pigeon, Roman_Catholic_Church, Romania, Royal_Navy, Russia, Russian_language, Rwanda, Sanskrit, Saurischia, Scientific_classification, Scouting, Season, Seed, Semiconductor, Sierra_Leone, Slavery, Snow, Somalia, Sony, South_Africa, South_China_Sea, Southern_Africa, Southern_United_States, Space_exploration, Spain, Speech_synthesis, Sport, Sri_Lanka, Star_Wars_Episode_IV__A_New_Hope, Sugar, Sumer, Switzerland, Syria, Television, The_Hitchhiker%2527s_Guide_to_the_Galaxy, Togo, Toy, Tropical_cyclone, Turkey, U.S._state, Ukraine, United_States_Constitution, United_States_dollar, Unix, Vatican_City, Vitamin, Wader, Wars_of_the_Roses, Weapon, Weather, Wikipedia, Wind, World_Health_Organization, World_War_II] F3 has size 283; articles in F3 but not in F4: [AT%2526T, Aesthetics, Apostolic_Succession, Applied_mathematics, Aquarium, Archbishop_of_Canterbury, Asia, Astronomy, Atlantic_Ocean, Automobile, Belgium, Bird, Botany, British_Empire, Child, China, Computer_science, DNA, Denmark, Dinosaur, Earth%2527s_atmosphere, Election, Electronics, English_language, Euro, Eye, Film, Folic_acid, France, Galaxy, Game, Ghana, Greece, Guatemala, Guinea, Heat, Hinduism, History_of_the_world, Horn_of_Africa, Hubble_Deep_Field, Hungary, Igneous_rock, India, Invertebrate, Ireland, Israel, Jakarta, Japan, Jazz, John_of_England, Jurassic, Law, Liverpool, Mesopotamia, Middle_East, Musical_instrument, Myanmar, Newspaper, North_Africa, Oceania, Open_source, Painting, Programming_language, Race, Ragtime, Renaissance, River, Robert_Baden-Powell%252C_1st_Baron_Baden-Powell, Roman_Empire, Sculpture, Silicon, Socialism, Sound, South_America, Sultan, Telecommunication, Temperate, Transport, Tropics, United_Nations, Wales, Windows_2000, World_Wide_Web] 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] F11 has size 101; articles in F11 but not in F12: [Business, England, Life, Religion] F12 has size 97; articles in F12 but not in F13: [Europe, Mythology, Organism] 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, 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