# Hee Kwon Lee

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bio website location Yuseong-gu, Daejeon, Korea age 35 member for 2 years, 4 months seen 21 hours ago profile views 878

I am studying Algebra.

# 1,230 Actions

 Dec9 awarded Caucus Nov28 comment Prove $\sin\ (\alpha'+\beta'+\gamma')\cos\ \beta \geq \sin\ \alpha' \cos\ \gamma+ \sin\ (\beta'+ \gamma')\cos\ (\alpha+\beta )$ I see. Thank you. Nov27 comment Prove $\sin\ (\alpha'+\beta'+\gamma')\cos\ \beta \geq \sin\ \alpha' \cos\ \gamma+ \sin\ (\beta'+ \gamma')\cos\ (\alpha+\beta )$ Note that $$\cos\ \beta\geq (\sin\ \alpha'-\cos\ \alpha')\cos\ \gamma$$ Not true is not clear. Nov27 asked Prove $\sin\ (\alpha'+\beta'+\gamma')\cos\ \beta \geq \sin\ \alpha' \cos\ \gamma+ \sin\ (\beta'+ \gamma')\cos\ (\alpha+\beta )$ Nov7 revised Group Action problem - Proving an action and finding number of orbits added 53 characters in body Nov7 answered Group Action problem - Proving an action and finding number of orbits Nov7 answered positive fractions, denominator 4, difference equals quotient Oct30 accepted Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ Oct30 comment Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ I see. I editted. Oct30 revised Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ edited body; edited title Oct30 comment Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ I know : When $A$ is projective, it is trivial. But the above reference uses a different notation, though others uses the notation as you said. Anyway I want to prove Proposition 1 in 34 page. Oct30 comment Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ math.unipd.it/~frank/ALGANT/2005/chap3a.pdf Oct30 asked Equivalence classes of extensions of ${\bf Z}_m$ by ${\bf Z}$ Oct20 comment Centralizer of $A_m$ in $A_n$ You are right. I edit again Oct20 revised Centralizer of $A_m$ in $A_n$ added 192 characters in body Oct20 revised Centralizer of $A_m$ in $A_n$ deleted 110 characters in body Oct20 comment Centralizer of $A_m$ in $A_n$ Well I will edit more clearly Oct19 revised Centralizer of $A_m$ in $A_n$ deleted 627 characters in body Oct19 comment Centralizer of $A_m$ in $A_n$ I see. I fix it. Oct19 revised Centralizer of $A_m$ in $A_n$ added 328 characters in body