Reputation
363
Top tag
Next privilege 500 Rep.
Access review queues
Badges
1 9
Newest
 Commentator
Impact
~3k people reached

  • 0 posts edited
  • 0 helpful flags
  • 15 votes cast
Mar
10
awarded  Commentator
Mar
10
comment Spotting that $\,x^8 + x^7 + 1\,$ is reducible.
(I recognize that this answer is essentially equivalent to the earlier answer phrased in terms of complex roots of unity; though therefore redundant, I am nonetheless cross-posting here in continuation of the discussion which originated at quora.com/… and was then directed here)
Mar
10
revised Spotting that $\,x^8 + x^7 + 1\,$ is reducible.
added 6 characters in body
Mar
10
revised Spotting that $\,x^8 + x^7 + 1\,$ is reducible.
added 6 characters in body
Mar
10
answered Spotting that $\,x^8 + x^7 + 1\,$ is reducible.
Dec
9
awarded  Caucus
Dec
3
comment Are all finite groups cyclic?
The error is that for Mobius inversion to work as you invoked it, it must be that $\sum_{d \mid m} \psi(d) = m$ for ALL $m$, but you've only shown it to hold for one particular $m$ (the order of the group).
Nov
13
awarded  Autobiographer
Aug
6
comment ind-completion and functors which are full with respect to isomorphisms
"My interpretation is that you are looking for a condition that says that there are no more L-isomorphisms between direct limits of K-structures than what you would get by taking formal direct limits.". Is this not the question of whether the canonical map from ind-$C_K$ into $C_L$ is iso-full?
May
12
revised Commuting limits in relating the harmonic series to coprimality densities
edited body
May
11
asked Commuting limits in relating the harmonic series to coprimality densities
Feb
25
comment Product of all elements in an odd finite abelian group is 1
This is essentially the classical proof of the general Lagrange's theorem (rather than the alternative proof, already invoked, which establishes Lagrange's theorem only for cyclic subgroups of a finite abelian group), specialized to this case. You are divvying G into its orbits under the action of the subgroup generated by j, noting that these orbits all have cardinality equal to the order of (the subgroup generated by) j, and thus concluding that the order of j divides the order of G.
Jan
12
awarded  Yearling
Aug
31
awarded  Scholar
Aug
31
accepted Derivatives as defined by a two variable difference quotient limit
Aug
30
comment Calculate $\pi$ to an accuracy of 5 decimal places?
What do you mean when you say "I know... how to choose how 'far' I should calculate"? Because that's precisely the question you are asking.
Aug
30
revised Derivatives as defined by a two variable difference quotient limit
added 10 characters in body
Aug
30
asked Derivatives as defined by a two variable difference quotient limit
Aug
30
comment Why use the derivative and not the symmetric derivative?
What happens if we remove the restriction that r > 0 and s > 0 (and just ask that they not sum to zero)? What extra properties must a function differentiable at x satisfy for the two-variable difference quotient limit (in r and s) to exist? [E.g., I believe it suffices for the function to be continuously differentiable. How tight a restriction is this?]
Jan
14
revised Gödel's incompleteness theorem can't be proven?
added 62 characters in body