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

Posted: Sat Dec 08, 2007 4:43 pm UTC
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.)

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

Posted: Sat Dec 08, 2007 5:06 pm UTC
I find it easier to see whats going on when a few words are used. Hence I use the word "contradiction"

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

Posted: Sat Dec 08, 2007 6:36 pm UTC
If I'm going symbolically I use a # like symbol ( \varhash in LaTeX ). I try to use words as much as possible though.

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

Posted: Sat Dec 08, 2007 6:36 pm UTC
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.

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

Posted: Sun Dec 09, 2007 5:50 am UTC
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...

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

Posted: Tue Dec 11, 2007 2:00 pm UTC
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).

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

Posted: Tue Dec 11, 2007 8:11 pm UTC
Lightening bolty thingie.

Tis awsomes.

My analysis teacher, uses its. I likes.

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

Posted: Wed Dec 12, 2007 3:17 am UTC
I just wrote it out, but I think I'll try some of these. They're cool!

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

Posted: Thu Dec 13, 2007 11:05 am UTC
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!)

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

Posted: Sat Dec 15, 2007 1:57 pm UTC
I usually go for