coincident-root-loci-0.3: Equivariant CSM classes of coincident root loci
Safe HaskellNone
LanguageHaskell2010

Math.RootLoci.CSM.Equivariant.PushForward

Description

Compute the pushforward maps pi_* and delta_* between the GL2-equivariant cohomology rings

Recall that:

  • Delta_nu : Q^d -> Q^n
  • pi : Q^n -> P^n

and Q^n = P^1 x P^1 x ... x P^1.

Synopsis

The function tau

tau :: ChernBase base => Int -> ZMod base Source #

tau_k := ( a^(k+1) - b^(k+1) ) / ( a - b )

tauEta :: ChernBase base => Int -> ZMod (Eta base) Source #

pushforward along the diagonal map Delta_{nu} : Q^d -> Q^n

delta_star_ :: ChernBase base => Partition -> ZMod (Omega base) -> ZMod (Eta base) Source #

delta_star :: ChernBase base => SetPartition -> ZMod (Omega base) -> ZMod (Eta base) Source #

delta_star' :: ChernBase base => [[Int]] -> ZMod (Omega base) -> ZMod (Eta base) Source #

We can give an explicit indexing scheme (set partition), instead of the linear indexing used above. This will be useful when computing the "open" part

pushforward along the order-forgetting map pi : Q^n -> P^n

pi_star_table :: Int -> Array Int (ZMod (Gam AB)) Source #

Table of pi_*( eta_1*eta_2*...*eta_k ), computed by breaking the symmetry.

compute_pi_star Source #

Arguments

:: Int

the number of points m (recall the pi : Q^m -> P^m)

-> ZMod (Eta AB) 
-> ZMod (Gam AB) 

Slow implementation of pi_star, using pi_star_table

pi_star Source #

Arguments

:: forall base. ChernBase base 
=> Int

the number of points m (recall the pi : Q^m -> P^m)

-> ZMod (Eta base) 
-> ZMod (Gam base) 

However it should faster to just use the recursion for the P_j(m) polynomials, which this function does.

Fibonacci-type recursion formula for pi_*