## What symbol do you use (in proofs) for contradiction?

For the discussion of math. Duh.

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## What symbol do you use for contradiction?

20
43%
Downward zigzag or lightning bolt (\blitza)
11
23%
5
11%
Perpendicular lines (\bot or \odplus)
2
4%
Struck-out arrows (\nleftrightarrow)
1
2%
That splat thingie (\textreferencemark)
2
4%
Something Else
6
13%

szarka
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### What symbol do you use (in proofs) for contradiction?

What symbol, if any, do you use to express contradiction when writing proofs? (The Comprehensive LaTeX Symbol List shows several alternatives on p.19 and suggests that there's no consensus.)
Last edited by szarka on Sun Dec 09, 2007 5:49 am UTC, edited 1 time in total.

SimonM
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### Re: What symbol do you use (in proofs) for contradiction?

I find it easier to see whats going on when a few words are used. Hence I use the word "contradiction"
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crazyjimbo
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### Re: What symbol do you use (in proofs) for contradiction?

If I'm going symbolically I use a # like symbol ( \varhash in LaTeX ). I try to use words as much as possible though.

Torn Apart By Dingos
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### Re: What symbol do you use (in proofs) for contradiction?

I use \bot when I write stuff by hand for myself. Otherwise I just write out "Contradiction.". I've started to use \blitza a little though, because it looks cool.

szarka
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### Re: What symbol do you use (in proofs) for contradiction?

Argh! I edited the poll to add a "something else" category and it reset everything. Bug or feature? Hard to say...

Anyway, I usually just use words, but my analysis prof may have converted me to the head-butting arrow thingie...

McHell
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### Re: What symbol do you use (in proofs) for contradiction?

Any symbol usage should refer to blackboard maths (and by extension, written exam paper maths).

If you follow proper math paper writing standards (e.g. [our lord] D. Knuth's stanford CS course on math writing) for a course book or reviewed paper: you arrive to the contradiction and then finish by a sentence pointing out how this is a contradiction.

So in BB maths it's clear writing "contradiction!" or "\$\blitza\$ is equivalent, hence the second in preferable if either (a) the *whole* audience knows what it stands for or (b) you make it clear in words, while writing the squiggle, that it stands for a contradiction (so you do orally what the written math version prescribes).

3.14159265...
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### Re: What symbol do you use (in proofs) for contradiction?

Lightening bolty thingie.

Tis awsomes.

My analysis teacher, uses its. I likes.
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ICDB
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### Re: What symbol do you use (in proofs) for contradiction?

I just wrote it out, but I think I'll try some of these. They're cool!

mudge
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### Re: What symbol do you use (in proofs) for contradiction?

I actually know of someone with the \blitza tattooed on them.

I however, usually use the headbutting arrows. The blitza is cooler, but the arrows were what I learned, and seem to make the most sense to me (It's like two implications colliding!)
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You, sir, name?
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### Re: What symbol do you use (in proofs) for contradiction?

I usually go for

It may be a bit of a superfluous redundancy, but it does cover all bases.
I edit my posts a lot and sometimes the words wrong order words appear in sentences get messed up.

Ended
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### Re: What symbol do you use (in proofs) for contradiction?

I use # for contradiction. Also, unless it's really obvious, I try to write '# of linear independence of the en' or whatever. I think just writing 'contradiction kthxbye', without explaining exactly what is being contradicted, is annoying for someone reading your work (not least when you go back to read it yourself).
Generally I try to make myself do things I instinctively avoid, in case they are awesome.
-dubsola

szarka
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### Re: What symbol do you use (in proofs) for contradiction?

My analysis prof calls the head-butting arrow thingie "Bulgarian contradiction". I think that's in honor of another prof at my school who uses it, but I'm never sure. Like many truly funny people, it's sometimes difficult to know when he's joking...