User bo.gu - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-26T08:55:32Z http://mathoverflow.net/feeds/user/20491 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/125861/f3-f2-are-the-cube-and-quadratic-of-f-respectively-and-both-infinite-differen $f^3,f^2$ are the cube and quadratic of f respectively and both infinite differentiable on $R$,how to show so is $f$ bo.gu 2013-03-28T23:40:35Z 2013-04-17T17:53:27Z <p>Let $f$ be a real function with domain R. If $f^2$ and $f^3$ are both infinite differentiable on R, How to prove $f$ be infinite differentiable on R</p> <p>This problem which I have been thinking it for a long period,but I I can not find a accurate proof .So if somebody can help me, I will be appreciative very deeply.</p> http://mathoverflow.net/questions/124672/functional-equation-how-to-solve/124675#124675 Answer by bo.gu for functional equation, how to solve bo.gu 2013-03-16T07:35:05Z 2013-03-16T07:35:05Z <p>Maybe you can first think the case n=1</p> http://mathoverflow.net/questions/124674/solvablity-for-some-polynomial solvablity for some polynomial bo.gu 2013-03-16T07:27:28Z 2013-03-16T07:27:28Z <p>We know that if F is a field which ch(F)=0,p(x) is a polynomial with coefficient of F,then p(x)root solvablity if and only if the Galois group of p(x) is solvablity .Here I want to know if the character of F is not zero ,how to judge the root solvablity ?Is there a analogue theorem?</p> http://mathoverflow.net/questions/114227/a-problem-about-field-extension/114231#114231 Answer by bo.gu for a problem about field extension bo.gu 2012-11-23T10:03:58Z 2012-11-23T10:06:32Z <p>If K and L are F-field extensions, K/F and L/F are both finite dimensional, and the isomorphism from K to L is an F-homomorphism, then the proof is easy, but the general case seems difficult. </p> http://mathoverflow.net/questions/114227/a-problem-about-field-extension a problem about field extension bo.gu 2012-11-23T09:42:35Z 2012-11-23T10:06:32Z <p>Let K and L are fields,L is a sub field of K,and L is isomorphic to K,whether can we get K=L?If true,how to prove? Thanks.</p> http://mathoverflow.net/questions/105067/how-to-partition-a-quadrilateral-into-a-finite-number-of-equal-area-triangles How to partition a quadrilateral into a finite number of equal-area triangles bo.gu 2012-08-20T02:31:05Z 2012-08-20T03:51:25Z <ol> <li><p>A quadrilateral can be partitioned into 2 equal-area triangles if and only if one diagonal divides equally the other diagonal.</p></li> <li><p>It can be proved that most quadrilaterals cannot be partitioned into 3 equal-area triangles.</p></li> <li><p>Conjecture: For any natural number $n$, there exists a quadrilateral that cannot be partitioned into $n$ equal-area triangles.</p> <p>How can one prove this?</p></li> </ol> <p>[Original question by <a href="http://mathoverflow.net/users/20491/bo-gu" rel="nofollow">bo.gu</a> (MO user20491).]</p> http://mathoverflow.net/questions/85393/an-ordinary-differential-equation an ordinary differential equation bo.gu 2012-01-11T07:26:45Z 2012-01-11T08:13:10Z <p>Does the ordinary differential equation $$\frac{dy}{dx}=1+\frac{log(1+x)-log(x)}{log(1+x+y)-log(x+y)}$$ have a solution that can be given in closed form?</p> http://mathoverflow.net/questions/127979/a-question-from-complex-analysis/128106#128106 Comment by bo.gu bo.gu 2013-04-20T03:27:17Z 2013-04-20T03:27:17Z @Peter Mueller,How do you find the Counter-example？ http://mathoverflow.net/questions/125861/f3-f2-are-the-cube-and-quadratic-of-f-respectively-and-both-infinite-differen/127724#127724 Comment by bo.gu bo.gu 2013-04-18T08:37:42Z 2013-04-18T08:37:42Z @Terry Tao,I do not konw your article until now. http://mathoverflow.net/questions/125861/f3-f2-are-the-cube-and-quadratic-of-f-respectively-and-both-infinite-differen/127709#127709 Comment by bo.gu bo.gu 2013-04-18T08:35:07Z 2013-04-18T08:35:07Z @Katz，I am a Chinese student,maybe I cannot understand your feeling exactly。I think you should not feel bad,they just give their views about this problem. http://mathoverflow.net/questions/125861/f3-f2-are-the-cube-and-quadratic-of-f-respectively-and-both-infinite-differen/127724#127724 Comment by bo.gu bo.gu 2013-04-17T22:24:05Z 2013-04-17T22:24:05Z Thank you very much http://mathoverflow.net/questions/125861/f3-f2-are-the-cube-and-quadratic-of-f-respectively-and-both-infinite-differen Comment by bo.gu bo.gu 2013-03-29T00:27:02Z 2013-03-29T00:27:02Z @Misha，f^2 means the square of f http://mathoverflow.net/questions/114227/a-problem-about-field-extension/114231#114231 Comment by bo.gu bo.gu 2012-11-23T10:37:39Z 2012-11-23T10:37:39Z O，I am a freshman in this website.Lots of thing need to learn. http://mathoverflow.net/questions/105067/how-to-partition-a-quadrilateral-into-a-finite-number-of-equal-area-triangles/105069#105069 Comment by bo.gu bo.gu 2012-08-20T02:41:31Z 2012-08-20T02:41:31Z thank you very much http://mathoverflow.net/questions/88505/occupational-diseases-of-mathematicians Comment by bo.gu bo.gu 2012-02-15T10:38:35Z 2012-02-15T10:38:35Z Dear Asaf Karagila,I am sorry . but since lots of famous set theorist,for example Cantor,Godel,were getted this ill ,I fill set theorists should encountered this problem more probably http://mathoverflow.net/questions/85393/an-ordinary-differential-equation Comment by bo.gu bo.gu 2012-01-11T08:19:02Z 2012-01-11T08:19:02Z A friend asked me, the origin of it ,I donot know