@meso Axioms are things that are just assumed to be true, definitions are descriptions of things. I'm trying to figure out what axiom or definition makes it the case that x <= x + 1.
If we just assume that x is a natural number, we can just say that x <= y if, when treated as von Neumann ordinals, every set in x is also in y, but I don't think this is standard.
I think I'm missing some properties of real numbers. Something like, if y >= 0, then x + y >= x, and if y < 0, x + y < x.
@meso@MercurialBlack watch your fire, i specifically avoid getting laid so i can keep servers under my bed and not get stupid questions like "what's that whirring sound"
@MercurialBlack@meso I think the thing you're missing is that 1*1 = 1 and (-1)*(-1) = 1. These are field properties, though...I don't think you need any of the rest of the structure on the reals to show this.
We can get the result we want just by proving that 0<1, and I think that this is somewhat clear from the first axiom Mist's first post.
You can prove this first: "For every a !=0 in R, exactly one of the two is true: a>0 or -a>0." If both of those are true (or if both of those are false) then you can show that the number in question is equal to zero, and that also follows from the first axiom in Mist's first post. (It *may* help to first prove "if a>b and c>d, then a+c > b+d")
Then, it follows that either 1>0 or -1>0. Then you can use the second axiom Mist posted to show that -1>0 is false.
@ceo_of_monoeye_dating@meso And I mean we need to be careful since >, < and >= don't exist in this case. I think equality still does, though, since a = b iff a <= b and b <= a.
@ceo_of_monoeye_dating@meso The whole thing that sparked this was my trying to prove a>=b and c>=d, then a+c >= b+d. That is, the monotonicity of the real numbers with a preorder relation.
@MercurialBlack@meso Which is reasonable. The first axiom says "addition doesn't dick with the order too much," and the second axiom says "the order points in the positive direction." These are natural things you'd want out of the reals.
@ceo_of_monoeye_dating@meso is that allowed? Manipulating both sides of a relation means applying a function which preserves the relation, so I'd think we'd need to prove that f(x) = x - b is monotonic