- #1
Kim.S.H
- 2
- 0
Hi, I'm studying multivariable analysis using Spivak's book "calculus on manifolds"
When I see this book, one strange problem arouse.
Thank you for seeing this.
Here is the problem.
c0 , c1 : [0,1] → ℝ2 - {0}
c : [0,1]2 → ℝ2 - {0}
given by
c0(s) = (cos2πs,sin2πs) : a circle of radius 1
c1(s) = (3cos4πs,3sin4πs) : a circle of radius 3 that winds twice.
c(s,t) = (1-t)*c0(s) + t*c1(s).
Then c(s,0) = c0(s) , and c(s,1) = c1(s).
Now the boundary of a 2-chain c is c0-c1.
Is this right?
If so, there is a problem.
If w = (-ydx + xdy)/(x2+y2) is a 1-form on ℝ2 - {0} , then it is closed.(i.e. dw = 0)
Then by the Stokes' theorem we get
-2π = ∫c0-c1w = ∫∂cw = ∫cdw = 0
Why this happened?
When I see this book, one strange problem arouse.
Thank you for seeing this.
Here is the problem.
c0 , c1 : [0,1] → ℝ2 - {0}
c : [0,1]2 → ℝ2 - {0}
given by
c0(s) = (cos2πs,sin2πs) : a circle of radius 1
c1(s) = (3cos4πs,3sin4πs) : a circle of radius 3 that winds twice.
c(s,t) = (1-t)*c0(s) + t*c1(s).
Then c(s,0) = c0(s) , and c(s,1) = c1(s).
Now the boundary of a 2-chain c is c0-c1.
Is this right?
If so, there is a problem.
If w = (-ydx + xdy)/(x2+y2) is a 1-form on ℝ2 - {0} , then it is closed.(i.e. dw = 0)
Then by the Stokes' theorem we get
-2π = ∫c0-c1w = ∫∂cw = ∫cdw = 0
Why this happened?