basis(ZZ,ZZ,ExtAlgebra) -- compute a basis

• Function: basis

• Usage:

  b=basis(m,n,E)

• Inputs:
  • m, an integer,
  • n, an integer,
  • E, an instance of the type ExtAlgebra,
• Optional inputs:
  • Degree => ..., default value null,
  • Limit => ..., default value infinity,
  • SourceRing => ..., default value null,
  • Strategy => ..., default value null,
  • Truncate => ..., default value false,
  • Variables => ..., default value null,
• Outputs:
  • b, a list, a basis for the part of $E$ of first degree $m$ and homological degree $n$.

i1 : L = lieAlgebra({a,b,c},Weights=>{{1,0},{2,1},{3,2}},
           Signs=>{1,1,1},LastWeightHomological=>true)

o1 = L

o1 : LieAlgebra

i2 : D= differentialLieAlgebra({0_L,a a,a b})

o2 = D

o2 : LieAlgebra

i3 : J=lieIdeal({b b + 4 a c})

o3 = J

o3 : FGLieIdeal

i4 : Q=D/J

o4 = Q

o4 : LieAlgebra

i5 : E=extAlgebra(5,Q)

o5 = E

o5 : ExtAlgebra

i6 : basis(4,4,E)

o6 = {ext_3}

o6 : List