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location Melbourne, Australia
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visits member for 4 years, 1 month
seen Jul 4 at 23:58

Aug
7
comment Interesting properties of ternary relations?
I'd be interested to hear some of those properties. The only one I can think of (off the top of my head) is R(x,y,z) <-> R(y,x,z).
Aug
3
comment Interesting properties of ternary relations?
I'm now sure why you put that as a comment rather than as an answer.
Aug
3
asked Interesting properties of ternary relations?
Aug
3
comment How do the Properties of Relations work?
Asymmetric does not mean "not symmetric" in the context of binary relations. The relation "x is a factor of y" is not symmetric (since 3 is a factor of 6 and not vice versa). But it is not asymmetric either by any standard definition of asymmetry.
Jul
30
accepted Characterising functions $f$ that can be written as $f = g \circ g$?
Jul
30
accepted Are there any interesting semigroups that aren't monoids?
Jul
29
awarded  Editor
Jul
29
comment Characterising functions $f$ that can be written as $f = g \circ g$?
@Qiaochu -- thanks for finding that for me. Could you put it as an answer to the question, optionally with a brief summary?
Jul
29
comment Characterising functions $f$ that can be written as $f = g \circ g$?
Thanks - fixed it.
Jul
29
revised Characterising functions $f$ that can be written as $f = g \circ g$?
fixed mistake in second example
Jul
29
asked Characterising functions $f$ that can be written as $f = g \circ g$?
Jul
29
comment Group with an endomorphism that is “almost” abelian is abelian
@Mariano, why don't you give that as the answer and then it can be accepted? Otherwise it looks as though nobody has answered the question.
Jul
29
accepted Why is the “finitely many” quantifier not definable in First Order Logic?
Jul
29
accepted How do you determine if a point sits inside a polygon?
Jul
29
accepted Why is $x^0 = 1$ except when $x = 0$?
Jul
28
accepted Why is the volume of a cone one third of the volume of a cylinder?
Jul
28
answered Optimal Strategy for Deal or No Deal
Jul
28
accepted Is $0$ a natural number?
Jul
28
comment Why is the “finitely many” quantifier not definable in First Order Logic?
Yes, I agree that the fact that I could define $P_3$ was irrelevant because of the inability to form an infinite disjunction, but I included it to give the question a bit of a context.
Jul
28
asked Why is the “finitely many” quantifier not definable in First Order Logic?