HK Lee
Reputation
7,548
95/100 score
 Apr 28 reviewed Close How many onto functions are there from a set with $5$ elements to a set with $3$ elements? Apr 22 answered How to apply the chain rule to $det A=\sum^n _{r=1} A_{ir} (cof A)_{ir}$? Apr 19 reviewed Close Solve integral of delta-function Apr 19 comment How to prove this formula involving the push-forward funtion The first part showed that vector in tangent space of $M$ is sended by $f_\ast$ into which one in tangent space of $N$, exactly. Apr 19 comment Prove that $p-$form $\omega$ on $M\times N$ is $\delta \pi(\alpha)$ iff $i(X)\omega=0$ and $L_X\omega=0$ Note that $(x,y)$ is chart for $M\times N$ so that $\omega$ is a combination of wedge products of $dx_i,\ dy_j$ But $\pi^\ast dy_i=dy_i$ so that $dx_i$ can not appear Apr 19 revised Prove that $p-$form $\omega$ on $M\times N$ is $\delta \pi(\alpha)$ iff $i(X)\omega=0$ and $L_X\omega=0$ added 48 characters in body Apr 19 comment Prove that $p-$form $\omega$ on $M\times N$ is $\delta \pi(\alpha)$ iff $i(X)\omega=0$ and $L_X\omega=0$ You are right I see I will correct it Apr 19 accepted Proof of coarea formula Apr 19 answered Prove that $p-$form $\omega$ on $M\times N$ is $\delta \pi(\alpha)$ iff $i(X)\omega=0$ and $L_X\omega=0$ Apr 19 revised How to prove this formula involving the push-forward funtion added 843 characters in body Apr 19 answered How to prove this formula involving the push-forward funtion Apr 16 reviewed Close Does every connected metric space , with more than one point , contains a path connected subset with more than one point ? Apr 16 reviewed Close Determine whether or not the following series is convergent $\sum_{n=1}^\infty \frac{1}{n^n}$ Apr 16 reviewed Close Find $\lim_{x \to -2, \ x < 2} \frac {2x+2} {x^2+x-2}$ Apr 16 reviewed Close Inverse image of a normal subgroup by a group homomorphism is a normal subgroup Apr 16 reviewed Close Proving a trigonometric identity: Apr 16 reviewed Close True or false under several conditions Apr 15 reviewed Close Is R/m a flat R-module? Apr 15 reviewed Close Proof for generators of cyclic group Apr 15 reviewed Leave Open Basic Symmetric Group Question