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		<id>https://www.explainxkcd.com/wiki/index.php?title=1417:_Seven&amp;diff=75252</id>
		<title>1417: Seven</title>
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				<updated>2014-09-05T12:28:19Z</updated>
		
		<summary type="html">&lt;p&gt;JennyS: /* Comic List */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 1417&lt;br /&gt;
| date      = September 5, 2014&lt;br /&gt;
| title     = Seven&lt;br /&gt;
| image     = seven.png&lt;br /&gt;
| titletext = The days of the week are Monday, Arctic, Wellsley, Green, Electra, Synergize, and the Seventh Seal.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
In this comic, Cueball (or perhaps Randall) says he can't distinguish between two sets if they both have exactly seven objects. This leads him to exchange the items in the sets without noticing, to the point where, when listing a set, every item truly belongs to a different set.&lt;br /&gt;
&lt;br /&gt;
The comic is a reference to the oldest {{w|Set-theoretic_definition_of_natural_numbers#Oldest_definition|set-theoretic definition of the natural numbers}} in which for each natural number, an equivalence class is defined over all sets which contain the same number of items.  As Cueball is known for mathematical thinking he could be presumed to have taken the underlying equivalence relation to heart, and (over)applying it to real life, genuinely judges sets to be identical if they both contain N objects.&lt;br /&gt;
&lt;br /&gt;
The number seven being the number for when sets become indistinguishable is possibly a reference to {{w|Miller's Law}}, however this refers to elements within the same set becoming indistinguishable, rather than indistinguishability of different sets of the same size.&lt;br /&gt;
&lt;br /&gt;
===Comic List===&lt;br /&gt;
# Disney's Dwarfs from the movie ''{{w|Snow White and the Seven Dwarfs(1937 film)|Snow White and the Seven Dwarfs}}'' (1937): '''Sneezy''', Dopey, Bashful, Sleepy, Grumpy, Happy, Doc&lt;br /&gt;
# Major {{w|taxonomic ranks}}: Kingdom, '''Phylum''', Class, Order, Family, Genus, Species&lt;br /&gt;
# Continents:  Asia, Africa, '''Europe''', North America, South America, Australia, Antarctica&lt;br /&gt;
# {{w|Seven deadly sins|Deadly sins}}: Lust, Gluttony, Greed, '''Sloth''', Wrath, Envy, Pride&lt;br /&gt;
# {{w|Seven-layer dip|Seven Layer Dip (recipe)}}: Refried beans, Cheese, Ground beef, Sour cream, '''Guacamole''', Salsa, Chopped black olives/Chopped tomatoes/Chopped green onions&lt;br /&gt;
# Layers of the {{w|OSI model|Open System Interconnection (OSI) data transmission model}}: Application, Presentation, Session, Transport, Network, '''Data link''', Physical&lt;br /&gt;
# {{w|Wonders of the World|Wonders of the Ancient World}}: Great Pyramid of Giza, Hanging Gardens of Babylon, Statue of Zeus at Olympia, Temple of Artemis at Ephesus, Mausoleum at Halicarnassus, Lighthouse of Alexandria, '''Colossus of Rhodes'''&lt;br /&gt;
&lt;br /&gt;
===Title Text List===&lt;br /&gt;
The title text extends this saying he also does the same with the set of the seven days of the week. The sets Cueball's &amp;quot;days of the week&amp;quot; come from are:&lt;br /&gt;
# Days of the week: '''Monday''', Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday&lt;br /&gt;
#{{w|Seven_Seas#Modern|The Seven Seas (modern version)}}: Pacific, Atlantic, Indian, '''Arctic''', Mediterranean, Caribbean, and the Gulf of Mexico.&lt;br /&gt;
## This could also be a reference to {{w|Climate zones}}: '''Arctic''', North Temperate, Northern Subtropical, Tropical, Southern Subtropical, South Temperate and Antarctic. &lt;br /&gt;
##There are however usually only five mentioned acording to the {{w|Köppen climate classification}}. They are: Tropical, Dry, Temperate, Continental and Polar climate.&lt;br /&gt;
# {{w|Seven Sisters (colleges)|Seven Sisters}}, historically women's colleges in U.S.: Mount Holyoke, Vassar, '''Wellesley''', Smith,  Radcliffe, Bryn Mawr and Barnard&lt;br /&gt;
# Traditional {{w|spectral color}}s: red, orange, yellow, '''green''', blue, indigo and violet (indigo stuck in to add up to seven notes in Western musical scale)&lt;br /&gt;
# {{w|Pleiades (mythology)|Pleiades}}, Seven Sisters, nymphs and daughters of Atlas and Pleone in Greek mythology: '''Electra''', Maia, Taygete, Alcyone, Celaeno, Sterope and Merope&lt;br /&gt;
# ''{{w|The Seven Habits of Highly Effective People}}'' by Dr. Stephen R. Covey:  Be proactive, Begin with the end in mind, Put first things first, Think win-win, Seek first to understand and then to be understood, '''Synergize'''' and Sharpen the saw&lt;br /&gt;
# {{w|Seven_Seals|Seals}} in the Book of Revelation in the New Testament: First seal, Second seal, Third seal, Fourth seal, Fifth seal, Sixth seal  and '''Seventh seal'''&lt;br /&gt;
&lt;br /&gt;
=Transcript=&lt;br /&gt;
: [Megan and Cueball are talking]&lt;br /&gt;
: Megan: Can you name all the dwarves from Snow White?&lt;br /&gt;
: Cueball: Sure, there's, um...&lt;br /&gt;
: Cueball's thoughts: Sneezy, phylum, Europe, sloth, guacamole, data link, Colossus of Rhodes&lt;br /&gt;
: Caption: I have this problem where all sets of seven things are indistinguishable to me.&lt;br /&gt;
{{comic discussion}}&lt;/div&gt;</summary>
		<author><name>JennyS</name></author>	</entry>

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