Re: Solve or Reduce on a monstrosity of an expresssion (and a prize!)
- To: mathgroup at smc.vnet.net
- Subject: [mg57388] Re: Solve or Reduce on a monstrosity of an expresssion (and a prize!)
- From: Daniel Reeves <dreeves at umich.edu>
- Date: Thu, 26 May 2005 04:31:35 -0400 (EDT)
- References: <200505230620.CAA04045@smc.vnet.net> <EEA0FBBD-9C31-419A-8D0B-7C73AE4DA32E@akikoz.net> <Pine.LNX.4.58.0505231817420.9452@boston.eecs.umich.edu> <458D701E-37FA-425F-89C4-52A5628E22CF@akikoz.net> <Pine.LNX.4.58.0505241736010.24188@boston.eecs.umich.edu> <1D91709F-1E4D-4B98-95F5-695F7BD65577@akikoz.net> <Pine.LNX.4.58.0505242049410.3527@boston.eecs.umich.edu> <F016112F-BF6B-4D4E-8A3C-1F38AB3DDC5F@akikoz.net>
- Sender: owner-wri-mathgroup at wolfram.com
yikes. ok, let's assume that all works. So it remains to show that both of the following expressions of n are zero for all n >= 2. Strangely, FullSimplify can do this for all specific n up to 113 but 114 seems to stump it. here are the expressions: ((-12*(-Sqrt[3] + 2*Sqrt[3]*n + 18*Sqrt[3]*n^2 + 34*Sqrt[3]*n^3 + 19*Sqrt[3]*n^4 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2] + 6*n^2*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2] - 3^(1/3)*(-1 + n)*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2]* (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (1/3))*(-3^(2/3) + 3^(2/3)*n^2 - 3*n^(4/3)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/ n)^(1/3) - 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))* (3^(2/3) - 2*3^(2/3)*n + 2*3^(2/3)*n^3 - 3^(2/3)*n^4 - 3*(-1 + n)*n^(7/3)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)* Sqrt[-3 + 21*n])/n)^(1/3) + 3*(-1 + n)* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (1/3) + 3^(1/3)*(-1 + n)^2* (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))^2)/((-1 + n)^4*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3)*(3^(1/3) - 3^(1/3)*n^2 + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))^3) + (6*(-Sqrt[3] + 19*Sqrt[3]*n^3 + 3*n*(Sqrt[3] + 2*Sqrt[-1 + 6*n + 7*n^2]) + 3*n^2*(5*Sqrt[3] + 4*Sqrt[-1 + 6*n + 7*n^2]))* (-3^(2/3) + 3^(2/3)*n^2 - 3*n^(4/3)* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^ (1/3) - 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))* (3^(2/3) - 3^(2/3)*n - 3^(2/3)*n^2 + 3^(2/3)*n^3 + 3*n^(7/3)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/ n)^(1/3) - 3*(n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)* Sqrt[-3 + 21*n])/n))^(1/3) + 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3) - 3^(1/3)*n*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))^2)/ ((-1 + n)^2*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (1/3)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n)* (3^(1/3) - 3^(1/3)*n^2 + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))^2) + ((3*3^(1/3) - 6*3^(1/3)*n^2 + 3*3^(1/3)*n^4 + 3*3^(2/3)*n^(7/3)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)* Sqrt[-3 + 21*n])/n)^(1/3) - 9*n^(5/3)* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^ (2/3) - 9*n^(8/3)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)* Sqrt[-3 + 21*n])/n)^(2/3) - 3*3^(2/3)* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (1/3) - 6*n^(8/3)*((1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3) + 6*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3) + 3^(2/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(4/3) - 3*3^(1/3)*(1 + n)*(9*n^2 + Sqrt[3]*Sqrt[-1 + 6*n + 7*n^2] + n*(9 + 2*Sqrt[3]*Sqrt[-1 + 6*n + 7*n^2])))* (9 + (3^(1/3)*((Sqrt[3]*(-1 + n)^3*(1 + n)^(3/2))/ (n*(1 + 2*n)*Sqrt[-1 + 7*n]) + 2*(9*(1 + n)^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))* (-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3)))/(n^(1/3)*(1 + n)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(4/3)) - (3*n^(2/3)*((-2*3^(2/3)*(-1 + n)^2*(1 + n))/n + (2*3^(1/3)*(-1 + n^2)^2*(-Sqrt[3] + 3*Sqrt[3]*n + 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]))/ ((-1 + n)*n^(4/3)*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* ((1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (1/3))))/((-1 + n^2)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(1/3))))/ (-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))^2 + (3*n^(4/3)*(1 + n)* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(2/3)* (3*n^(1/3) + (-3^(2/3) + 3^(2/3)*n^2 - 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))/ ((1 + n)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/ n)^(1/3)))*(9 - (6*3^(1/3)*(-1 + n)*(-Sqrt[3] + 2*Sqrt[3]*n + 18*Sqrt[3]*n^2 + 34*Sqrt[3]*n^3 + 19*Sqrt[3]*n^4 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2] + 6*n^2*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2] - 3^(1/3)*(-1 + n)*(1 + 2*n)* Sqrt[-1 + 6*n + 7*n^2]*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(1/3)))/ (n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3)) + (3*3^(1/3)*(-Sqrt[3] + 2*Sqrt[3]*n + 18*Sqrt[3]*n^2 + 34*Sqrt[3]*n^3 + 19*Sqrt[3]*n^4 + 6*n*(1 + n)^(3/2)*(1 + 2*n)* Sqrt[-1 + 7*n])*(-3^(1/3) + 3^(1/3)*n^2 - (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3)))/((1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (4/3)) - (2*3^(2/3)*(-1 + n)*(-Sqrt[3] + 2*Sqrt[3]*n + 18*Sqrt[3]*n^2 + 34*Sqrt[3]*n^3 + 19*Sqrt[3]*n^4 + 6*n*(1 + n)^(3/2)*(1 + 2*n)*Sqrt[-1 + 7*n])* (3^(1/3) - 3^(1/3)*n^2 + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))^2)/ (n^(8/3)*(1 + n)^(3/2)*(1 + 2*n)*Sqrt[-1 + 7*n]* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^ (5/3)) + (3^(1/3)*(-1 + n)^2*((Sqrt[3]*(-1 + n)^3*(1 + n)^(3/2))/ (n*(1 + 2*n)*Sqrt[-1 + 7*n]) + 2*(9*(1 + n)^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))* (-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3)))/((-1 + n^2)*(n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^(4/3)) + (3*(-1 + n)*(-3^(2/3) + 3^(2/3)*n^2 - 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3)))/(n^(4/3)*(1 + n)* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^ (1/3)) + (3*n^(2/3)*((-2*3^(2/3)*(-1 + n)^2*(1 + n))/n + (2*3^(1/3)*(-1 + n^2)^2*(-Sqrt[3] + 3*Sqrt[3]*n + 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]))/ ((-1 + n)*n^(4/3)*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* ((1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (1/3))))/((-1 + n^2)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(1/3)) + (2*3^(1/3)*(-1 + n)^2*(-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))*((-2*3^(2/3)*(-1 + n)^2*(1 + n))/n + (2*3^(1/3)*(-1 + n^2)^2*(-Sqrt[3] + 3*Sqrt[3]*n + 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]))/ ((-1 + n)*n^(4/3)*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* ((1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (1/3))))/((-1 + n^2)^2* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (2/3)) + (3^(1/3)*n^(2/3)*((-1 + n)/n - ((-1 + n)*(-3^(2/3) + 3^(2/3)*n^2 - 3^(1/3)* (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/ n))^(2/3)))/(3*n^(4/3)*(1 + n)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(1/3)))* (-(((Sqrt[3]*(-1 + n)^3*(1 + n)^(3/2))/(n*(1 + 2*n)*Sqrt[-1 + 7*n]) + 2*(9*(1 + n)^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))* (-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3))) + 2*(-1 + n^2)*(9*(1 + n)^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/ n)*(-3*3^(1/3) + (3*(1 + n)^(2/3)*(-Sqrt[3] + 3*Sqrt[3]*n + 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]))/((-1 + n)*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (1/3)))))/((1 + n)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(4/3)) + 3*n*(-1 - ((-1 + n)*(-3^(2/3) + 3^(2/3)*n^2 - 3^(1/3)*(n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^(2/3)))/(3*n^(4/3)*(1 + n)* (9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^ (1/3)))*(3 + (3^(1/3)*(-Sqrt[3] + 2*Sqrt[3]*n + 18*Sqrt[3]*n^2 + 34*Sqrt[3]*n^3 + 19*Sqrt[3]*n^4 + 6*n*(1 + n)^(3/2)*(1 + 2*n)* Sqrt[-1 + 7*n])*(-3^(1/3) + 3^(1/3)*n^2 - (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/ n))^(2/3)))/((1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* (n*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n))^ (4/3)) + (n^(2/3)*((-2*3^(2/3)*(-1 + n)^2*(1 + n))/n + (2*3^(1/3)*(-1 + n^2)^2*(-Sqrt[3] + 3*Sqrt[3]*n + 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 + 6*n*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]))/ ((-1 + n)*n^(4/3)*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2]* ((1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/ n))^(1/3))))/((-1 + n^2)*(9 + 18*n + 9*n^2 + ((1 + n)^(3/2)*(1 + 2*n)*Sqrt[-3 + 21*n])/n)^(1/3)))))/ ((-1 + n)*(-(3^(1/3)*(-1 + n)*(1 + n)) + (n*(1 + n)*(9 + 9*n + (Sqrt[3]*(1 + 2*n)*Sqrt[-1 + 6*n + 7*n^2])/n))^ (2/3))^2))/(18*3^(2/3)) and: (-2*(1 + n)* (((1 + n)^4*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))/((-1 + n)*n^2))^(2/3)* ((3*3^(1/3)*(1 + n)^3)/n - (3*(1 + n)^(7/3)*(Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)* Sqrt[1 + 7*n]*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n)^(1/3)))*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*((-9*(1 + n)^2)/((-1 + n)*n) + (n^(4/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(2/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*( -1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2)/ (1 + n)^(14/3) + (3*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/(1 + n)^(7/3) + (3*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ ((-1 + n)^(2/3)*(n*(1 + n)*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^ (1/3)) + 9*n*(-1 + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3* (27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))))/ (3^(2/3)*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^3) - ((1 + n)^(5/3)* ((-1 + n)/(n*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])))^(1/3)* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*((-9*(1 + n)^2)/((-1 + n)*n) + (n^(4/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(2/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*( -1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2)/ (1 + n)^(14/3) + (3*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/(1 + n)^(7/3) + (3*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ ((-1 + n)^(2/3)*(n*(1 + n)*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^ (1/3)) + 9*n*(-1 + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3* (27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))))/ (3*((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2) + ((1 + n)*(((1 + n)^4*(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))/ ((-1 + n)*n^2))^(2/3)* (9 - (3*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* ((2*3^(2/3)*(1 + n)^3)/n - (2*3^(1/3)*(1 + n)^(7/3)* (Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/ ((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)*Sqrt[1 + 7*n]* (9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*(-1 + n + 2*n^2))/n)^ (1/3))))/(1 + n)^(7/3) - (n^(5/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(4/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])))/(1 + n)^(13/3))* ((-9*(1 + n)^2)/((-1 + n)*n) + (n^(4/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(2/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*( -1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2)/ (1 + n)^(14/3) + (3*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/(1 + n)^(7/3) + (3*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ ((-1 + n)^(2/3)*(n*(1 + n)*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^ (1/3)) + 9*n*(-1 + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3* (27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))))/ (18*((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2) + ((1 + n)*(((1 + n)^4*(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))/ ((-1 + n)*n^2))^(2/3)*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* ((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))* (27 + (9*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^ (1/3)*((2*3^(2/3)*(1 + n)^3)/n - (2*3^(1/3)*(1 + n)^(7/3)* (Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/ ((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)*Sqrt[1 + 7*n]* (9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*(-1 + n + 2*n^2))/n)^ (1/3))))/(1 + n)^(7/3) + (9*((2*3^(2/3)*(1 + n)^3)/n - (2*3^(1/3)*(1 + n)^(7/3)* (Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/ ((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)*Sqrt[1 + 7*n]* (9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*(-1 + n + 2*n^2))/n)^ (1/3))))/((-1 + n)^(2/3)* (n*(1 + n)*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)) - (9*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/(1 + n)^(7/3) + (6*n^(4/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(2/3)* ((2*3^(2/3)*(1 + n)^3)/n - (2*3^(1/3)*(1 + n)^(7/3)* (Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/ ((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)*Sqrt[1 + 7*n]* (9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*(-1 + n + 2*n^2))/n)^ (1/3)))*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/(1 + n)^(14/3) + (2*((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*( -1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])))/ (n*(((1 + n)^4*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))/((-1 + n)*n^2))^(5/3)) + (3*n^(5/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(4/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])))/(1 + n)^(13/3) + (3*(-1 + n)^(1/3)*n^(2/3)*(-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])))/((1 + n)^(7/3)* (9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])^(4/3)) + 3*n*(-1 + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))* (9 + (3*n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]* Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* ((2*3^(2/3)*(1 + n)^3)/n - (2*3^(1/3)*(1 + n)^(7/3)* (Sqrt[3] + 3*Sqrt[3]*n - 15*Sqrt[3]*n^2 + 19*Sqrt[3]*n^3 - 6*n*Sqrt[(-1 + n)*(1 + 7*n)] + 12*n^2*Sqrt[(-1 + n)*(1 + 7*n)]))/ ((-1 + n)^(1/6)*n^(4/3)*(-1 + 2*n)*Sqrt[1 + 7*n]* (9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]*(-1 + n + 2*n^2))/n)^ (1/3))))/(1 + n)^(7/3) + (n^(5/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3* (27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(4/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/(n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/ ((-1 + n)*n^2))])))/(1 + n)^(13/3)) - (3*(1 + n)*(-((1 + n)^2/((-1 + n)*n)) + (n^(2/3)*((-1 + n)/(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))^(1/3)* (-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3)))/ (3*(1 + n)^(7/3)))*(-((-((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2)) + 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))* ((Sqrt[3]*(1 + n)^5*Sqrt[(-1 + n)/(1 + 7*n)])/ (n*(1 - 3*n + 2*n^2)) + 2*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)* n^2))]))) - (2*3^(1/3)*(1 + n)^4*(-1 + n^2)* (9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))])*(3*3^(1/3) - ((Sqrt[3]*(1 + n)^4*Sqrt[(-1 + n)/(1 + 7*n)])/ (n*(1 - 3*n + 2*n^2)) + 2*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/ (-1 + n)]*(-1 + n + 2*n^2))/n))/ (((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(1/3)))/ ((-1 + n)^2*n^2)))/ (((1 + n)^4*(9*(1 + n)^2 + Sqrt[3]*Sqrt[(1 + n)^3*(27*(1 + n) + (1 + n)^4/((-1 + n)*n^2))]))/((-1 + n)*n^2))^(4/3)))/ (6*((3^(2/3)*(1 + n)^5)/((-1 + n)*n^2) - 3^(1/3)*(((1 + n)^5*(9 + 9*n + (Sqrt[3]*Sqrt[(1 + 7*n)/(-1 + n)]* (-1 + n + 2*n^2))/n))/((-1 + n)*n^2))^(2/3))^2) --- \/ FROM Andrzej Kozlowski AT 05.05.25 12:42 (Today) \/ --- > *This message was transferred with a trial version of CommuniGate(tm) Pro* > > On 25 May 2005, at 10:00, Daniel Reeves wrote: > > > *This message was transferred with a trial version of CommuniGate > > (tm) Pro* > > wow, this is huge progress. medium prize, at the least, is cinched :) > > > > eager to hear how you establish that the derivative has <= 2 roots... > > First, I only think I could probably prove this, but that does not > mean I actually have a rigorous proof. I have a sketch of a possible > proof that I will describe, but it may not work. What is worse, even > if it is essentially correct, it is probably the easy part of the > problem. Checking the two "simple identities" for every integer may > turn out to be awfully hard, perhaps as hard as Fermat's Last Theorem? > So I don't think that my contribution so far deserves any prize :-( > > Anyway, this is my idea for a argument proving that D[f[x,n]]==0 has > only two roots, for every n. For each complex number n, think of the > expression D[f[x,n]] as an element of the field Al of "algebraics" > over the complex numbers, that is the algebraic closure of the field C > [x] of rational functions in one variable with coefficients in the > complex numbers C. This is not just an algebraic object but also a > topological space. Each element f[x] of Al can be thought as a > function on C given by a radical expression like the one in your > problem. We know that for each f[x] there is a polynomial p[x] such > that all the roots of f[x]==0 are also roots of p[x]==0. As Daniel > Lichtblau pointed out in a recent posting the function > First[GroebnerBasis[f[x],x]] gives such a polynomial. I think one > can probably make sure that the polynomial is monic, that is, its > highest degree term is 1. So consider the mapping f[x]->First > [GroebnerBasis[f[x],x]] from the topological space Al to the space of > all polynomials in one variable. Now, here comes the point I am most > uncertain about: I think this mapping can be made continuous. In > other words, if we change our radical expression f[x] only slightly > than the corresponding polynomial will only change slightly. In > particular, it's degree will not jump. If that is so we are nearly > done. We need only to check only one more thing, which is that any > expression D[f[x,n],x] can be connected to D[f[x,m],x] by a > continuous path. Looking at the monstrous expression it seems to me > that it is so, anyway, as long as we keep n>1 . But since we can > compute the polynomial for a number of integers n and we know that it > has degree 2, it would seem to follow that it must always have degree 2. > > To really be sure the argument is correct would require very good > understanding of what the GrobenerBasis algorithm really does in such > situations and I have only a vague understanding. In particular I > have never seen anywhere the issue of continuity being discussed, but > then I have not looked for it. > But one must remember even if we could prove this we could still be > almost as far from proving the full statement as we were at the start. > > Andrzej Kozlowski > > > > > > > > > > > --- \/ FROM Andrzej Kozlowski AT 05.05.25 09:16 (Tomorrow) \/ --- > > > > > >> I am now pretty sure that I could now prove the general result > >> provided that I could establish two "simple" facts, which are that: > >> > >> > >> FullSimplify[D[f[x, n], x] /. x -> (n - 1)/n, > >> Element[n,Integers] && n > 2] > >> > >> FullSimplify[D[f[x, n], x] /. > >> x -> (-n^2 - 2*n - 1)/((n - 1)*n), > >> Element[n,Integers] && n > 2] > >> > >> are both zero. In other words, I think I can prove (there are some > >> details that I would have to check but I am pretty sure they are > >> fine) that the derivative can have no more than two roots, so if > >> the above are the roots everything is done. But unfortunately after > >> 24 hours Matheamtica has not returned any answer to the first of the > >> above. I have not even tried the second. > >> Perhaps a more specialized algebra program for this sort of thing > >> might do better? > >> > >> Andrzej Kozlowski > >> > > > > -- > > http://ai.eecs.umich.edu/people/dreeves - - google://"Daniel Reeves" > > > > "I have enough money to last me the rest of my life, unless I > > buy something." -- Jackie Mason > > > > > -- http://ai.eecs.umich.edu/people/dreeves - - google://"Daniel Reeves" "Engineers think of their equations as approximating reality. Scientists think of reality as approximating their equations. Mathematicians don't care."
- References:
- Solve or Reduce on a monstrosity of an expresssion (and a prize!)
- From: Daniel Reeves <dreeves@umich.edu>
- Solve or Reduce on a monstrosity of an expresssion (and a prize!)