minCoarsenWS -- Coarsens a given Whitney stratification to the unique minimal one.

• Usage:

  minCoarsenWS(WS)

• Inputs:
  • WS, a mutable hash table, a MutableHashTable storing a Whitney stratification (produced by either whitneyStatify or whitneyStatifyPol).
• Optional inputs:
  • Algorithm (missing documentation) => ..., default value "saturate",
  • Print (missing documentation) => ..., default value false,
• Outputs:
  • minWS, a MutableHashTable storing the unique minimal Whitney stratification obtained by coarsening the given one.

i1 : R=QQ[x..z]

o1 = R

o1 : PolynomialRing

i2 : I=ideal(y^2*z-x^2)

            2     2
o2 = ideal(y z - x )

o2 : Ideal of R

i3 : WS= whitneyStratifyPol I

o3 = MutableHashTable{...3...}

o3 : MutableHashTable

i4 : peek WS

o4 = MutableHashTable{0 => {ideal (z, y, x), ideal (1747430111571076z - 258644393880625, y, x)}}
                      1 => {ideal (y, x)}
                                   2     2
                      2 => {ideal(y z - x )}

i5 : mWS=minCoarsenWS WS

o5 = MutableHashTable{...3...}

o5 : MutableHashTable

i6 : peek mWS

o6 = MutableHashTable{0 => {ideal (z, y, x)}}
                      1 => {ideal (y, x)}
                                   2     2
                      2 => {ideal(y z - x )}