Jim
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 Apr 15 comment Determine if $g$ is a ring homomorphism Write down the formula that must hold for $g$ to commute with multiplication and then look for a counterexample. Apr 15 answered Listing all the ideals of a quotient ring Apr 14 answered Jordan Canonical form 3x3 Apr 14 comment Jordan Canonical form 3x3 The characteristic polynomial of a 3x3 matrix should have degree 3, you've written down something that has degree 4. Feb 28 awarded Enlightened Jan 10 awarded Yearling Dec 14 awarded Nice Answer Nov 22 comment Triangulation of the Klein Bottle I disagree, but we may be talking about two different things. When he says edge 12 is shared by 4 triangles I think that means he's identifying all four edges of the square. I'm only identifying the top/bottom edges with themselves and the left/right edges with themselves. I see now this isn't explicit in the OP's picture, but it makes the answer correct and it's what I assume he meant. Sep 24 answered If $G$ is a group with $|G|=2m$ and $m$ odd, then $G$ has exactly one element of order two Sep 8 revised Semidirect product structure of Dihedral group added 83 characters in body Sep 8 revised Semidirect product structure of Dihedral group added 83 characters in body Sep 8 answered Semidirect product structure of Dihedral group Sep 8 comment Semidirect product structure of Dihedral group What is $p$? Is it $2$? Sep 8 comment Equal on an open subset implies equal on the whole space? @darijgrinberg: That should be an answer. Sep 4 revised About group actions added 17 characters in body Sep 4 comment About group actions Yea, I wrote the second paragraph before they posted that link, I agree that order is probably not what they're talking about. Sep 4 answered About group actions Sep 4 answered How did they derive the image from kernel? Sep 4 comment Is this basic fact about prime pairs obvious? @lulu: The question is about the relationship between the sets $A_p$ and $A_q$ when $p, q$ is a pair of prime numbers. That's what the "prime pair" in the title refers to. Sep 4 answered Is this basic fact about prime pairs obvious?