# Comments from “is zero odd or even?”

Were getting a little too heated and filled with spam flags for my taste, so here they are. I think this is the protocol we agreed to, anyway. Original question.

0/2=0, 0mod2=0... what else do you want? – J. M. 9 hours ago
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What book says "even numbers start from two"? I want to know what to tell people to avoid... – Pete L. Clark 8 hours ago
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+1 for "thinking outside the books". – Day Late Don 8 hours ago

why −1 is an odd number? This is not a question that can have a real answer. It is matter of definition, There are two ways that definitions are made, constructive and conditional. Constructive definition for even numbers can be something like this : k=1,2,3,4,5,… then 2k are the even numbers , here without explicitly having 0 as a value for k, 0 must not be considered to be an even number. Conditional definition : e.g. a number k is even if and only if kmod2=0. then 0 can be considered even since it passes the test. – Arjang 7 hours ago

@Arjang: −1 is an odd integer because it is of the form 2n+1 for some integer n. That's my definition of odd. – TonyK 7 hours ago

@TonyK. and what that integer n might be? – Arjang 7 hours ago

@Arjang: have you tried to find it? – Mariano Suárez-Alvarez 7 hours ago

@Mariano Suárez-Alvarez : yes, this guy came to my store and asked me to give him odd number of eggs, he would accept 1,3,5 ,7,.. eggs but he just wouldn't accept -1 eggs as odd number of eggs. I am totally baffled why -1 egg is not acceptable as odd number of eggs. Do you have any idea why somebody might not accept -1 eggs as odd number of eggs? – Arjang 7 hours ago
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@Arjang: if your point is that -1 is not an integer, well, then you are wrong according to the definition used by mathematicians. What egg-buyers consider an integer is, really, irrelevant. – Mariano Suárez-Alvarez 7 hours ago
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@Arjang: This guy came to your store? And asked you to give him an odd number of eggs? Call me cynical, but I think you're lying. – TonyK 7 hours ago

@Mariano Suárez-Alvarez : yes -1 is an integer, but it is not a natural number. The even odd concept was originally defined for natural numbers not integers. Otherwise if the even/odd concept was defined over integers there wouldn't be a doubt over 0 or -1 being even or odd. Just because one way to extend the concept makes them even or odd it doesn't mean that by the original concept they are even or odd. – Arjang 7 hours ago

@TonyK, Next time you try to convince somebody that -1 eggs is an odd number of eggs, try to get them to count it just to be sure. – Arjang 6 hours ago

• I put my comment back, not realizing it had been moved here. (Shouldn't you have left a comment saying that you moved the comments?) My comment was neither heated nor spammy, but sincerely congratulatory. – Blue Dec 27 '10 at 0:35
• @Day Late Don: I guess I didn't want to make it appear to the OP that I was singling out his/her voice in the comments. It seemed cleaner to me to move the whole thing here (and I have to admit I thought you were referring to another comment). My apologies. – Qiaochu Yuan Dec 27 '10 at 0:50
• In before Arjang's comment, things were fine... :( – J. M. isn't a mathematician Dec 27 '10 at 0:51
• One thing I am slightly worried about is whether users have been flagging the answer post as SPAM/offensive with the intended target being the comments posted (e.g. some of the ones duplicated above). It is not entirely clear to me whether in situations like this (a dubious [IMHO] answer with some possibly inflammatory comments by the same user) such flagging is warranted. – Willie Wong Dec 27 '10 at 12:26
• @Willie: those comments reposted by Qiaochu were comments to the question; there were a different set of comments (e.g. "It is good to see that nonsense like this is downvoted") for Arjang's answer. In any event, the damage to Arjang has been done, as he is back to having a reputation score of 1. – J. M. isn't a mathematician Dec 27 '10 at 12:32
• Oh. I misunderstood. So those comments above were picking up the SPAM flags. Okay, sorry about the noise. – Willie Wong Dec 27 '10 at 18:06
• @J. M. : Which comment of mine screwed it up? – jimjim Dec 27 '10 at 21:23