I Is there an on-line table of genus of algebraic functions?

  • I
  • Thread starter Thread starter aheight
  • Start date Start date
  • Tags Tags
    Functions Table
aheight
Messages
318
Reaction score
108
Hi,

Given the algebraic function ##w(z)## defined implicitly as ##f(z,w)=a_0(z)+a_1(z)w+a_2(z)w^2+\cdots+a_n(z)w^n=0##,
is there any on-line table of genus for them? Haven't been able to find anything. I am writing some code and would like to check it against a standard source. For example,
##f(z,w)=(z^4)+(2 z^2+z^4)w+(1+z^2+z^3)w^2+(z)w^3+(1/4-z/2)w^4+(-(1/2))w^5## has genus of 1 according to my calculations. And ##f(z,w)=(2+3 z-z^2)+(z^3+9 z^4)w+(-z-7 z^4)w^2+(-3 z)w^3+(2+4 z-4 z^3)w^4+(-8+z^2-7 z^3+3 z^4)w^5## has genus of 12. Not sure my calculations are correct. I am using the formula:

## g=1/2 \sum_{p} (r-1) -n+1##

Might be useful to have an on-line table I think. What do you guys think?

Thanks,
 
Last edited:
Physics news on Phys.org
A sphere as topological manifold can be defined by gluing together the boundary of two disk. Basically one starts assigning each disk the subspace topology from ##\mathbb R^2## and then taking the quotient topology obtained by gluing their boundaries. Starting from the above definition of 2-sphere as topological manifold, shows that it is homeomorphic to the "embedded" sphere understood as subset of ##\mathbb R^3## in the subspace topology.
Back
Top