143 reputation
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bio website andyhayden.co.uk
location London, United Kingdom
age 29
visits member for 2 years, 4 months
seen Jul 7 at 18:47

"... there is no such word as 'impossible' in my dictionary. In fact, everything between 'herring' and 'marmalade' appears to be missing." — Svlad Cjelli

Make it a Short, Self Contained, Correct (Compilable), Example.

learning
Always learning.

github: https://github.com/hayd
careers: http://careers.stackoverflow.com/hayd


Mar
22
comment Commutator subgroup - or?
Is there a typo here, $\alpha(a^{-1})a$ is just $\alpha$...?
Oct
27
comment find $\dim X\times \mathbb{P}^{2}$
@spencer What's the definition of times?
May
12
comment Should every group be a monoid, or should no group be a monoid?
Is Definition 2 also incorrect/insufficient (for similar reasons to Definition 2'?)
Nov
14
comment Is this an open problem?
I don't see why we only consider primes? oeis.org/A069035
Nov
14
comment Is this an open problem?
@Salahuddin not really, just a subsequence of this: oeis.org/A069035
Aug
21
comment Why $\mathbb{Z}_p^*$ is a cyclic group?
Um, $\mathbb{Z}_2 \times \mathbb{Z}_3$ is abelian, but $2\nmid 3$.
Aug
21
comment Why $\mathbb{Z}_p^*$ is a cyclic group?
Please could you elaborate on the final sentence?
Aug
21
comment find $\dim X\times \mathbb{P}^{2}$
What have you tried so far? Isn't $dim(X \times Y)=dim(X)+dim(Y)$? So aren't you really only asking what is $dim(X)$?
Aug
20
comment Why isn't math on the sine of angles the same as math on the angles in degrees?
@nbubis In which case linear does not imply additive, see examples above. :)
Aug
20
comment Why isn't math on the sine of angles the same as math on the angles in degrees?
@nbubis Take care, it's not true for f(x)=1 or f(x)=x+1, as these are "affine" rather than "linear".
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
@celtschk haha, ok my bad, what I really meant to say was "how can you say that without doing some kind of calculation".
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
@celtschk I wouldn't say that is any more obvious that the difference of two squares.
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
So you're not using "then $x^3 \neq y^3$ in line 2 at all, this was the confusing bit. I now see what you are trying to say in the last part, well done.
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
@Exile.90 You are implicitly using the fact the $f(x)=x^3+x$ is increasing, this needs to be demonstrated or at least mentioned. Your argument seems to use $a \neq b$ and $c \neq d$ $\implies$ a+c $\neq$ b+d (which is not true).
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
You're saying that $x=y$ doesn't imply $x^3=y^3$, i.e. cubed isn't function over the complex numbers?? You're wrong.
Jul
18
comment Proof: For all integers $x$ and $y$, if $x^3+x = y^3+y$ then $x = y$
@Brad How would you know that: ( x^2+y^2+xy+1 =/= 0) without doing the difference of two squares calculation?
Mar
12
comment Cauchy Sequence that Does Not Converge
@Michael surely every sequence can be thought of as a series?