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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,664

A new page: Set Symbols

What do you guys think of it? Any mistakes?

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**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi MIF;

Looks pretty good. I am not following how to get the complement of A as {1,9}.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

I think you defined C and D but forgot A. Although you only use A in 1 example so you can just write D complement instead.

*Last edited by ShivamS (2014-11-17 13:34:24)*

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,664

Good point, will amend.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**ganesh****Administrator**- Registered: 2005-06-28
- Posts: 23,467

Hi MathsIsFun,

I think the symbols/notations are exhausted! Great job!

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Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,037

Hi MIF

Not sure if that's the general case, but I've seen the bolded "I" be used mostly for irrational numbers.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**MathsIsFun****Administrator**- Registered: 2005-01-21
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Has anyone else seen I used for irrationals?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,170

hi MathsIsFun,

Good page.

: is also used to mean 'such that'.

http://en.wikipedia.org/wiki/List_of_ma … al_symbols

The complement of a set only has meaning if the 'universe' is defined.

http://en.wikipedia.org/wiki/Complement_(set_theory)

so you could have: if **U**, the universe, = {1,2,3,4,5,6,7,8,9} and A = {2,3,4,5,6,7,8} then Asuperscriptc = {1,9}

There does not appear to be a regularly used symbol for the irrationals. Wolfram and Wiki do not have one. Maths Exchange has several suggestions (none of which I've ever seen used) but R−Q would seem to do the job.

Bob

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**MathsIsFun****Administrator**- Registered: 2005-01-21
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Great, will add : and define a Universal Set for the Complement example.

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**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,037

Also, A\B can be used to mean A-B.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

The knowledge of some things as a function of age is a delta function.

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

You might also want to include some symbols like the symmetric difference, relative complement and aleph-null.

MathsIsFun wrote:

Has anyone else seen I used for irrationals?

No, but neither have I seen "I" represent the "set of imaginary numbers".

bob bundy wrote:

There does not appear to be a regularly used symbol for the irrationals.

I believe the standard is R-Q. Q with a horizontal line on it, or R\Q.

*Last edited by ShivamS (2014-11-18 07:26:28)*

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,664

Thanks!

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