// given a vectorial Booleand function in univariate form, returns its delta rank
function deltaRank(f) 
R:=Parent(f);
F:=BaseRing(R); n:=Degree(F);
Gt<[E]>:=FreeAbelianGroup(2*n);
G<[E]>:=AbelianGroup(quo<Gt|{2*e=0 : e in E}>);
A1 := GroupAlgebra(  ComplexField(), G : Rep:="Vector"); A := GroupAlgebra( GF(2), G : Rep:="Vector");
function rr1(v)
return &+[E[i]*(Integers()!v[i]): i in [1..n]];
end function;
function rr2(v)
return &+[E[i+n]*(Integers()!v[i]): i in [1..n]];
end function;
FF:=ANF(f);
Gf:=[rr1(v)+rr2([Evaluate(FF[i],[v[j]:j in [1..n]]) : i in [1..n]]) : v in VectorSpace(GF(2),n)];

Gf:=&+[A1!g : g in Gf];
Df:= Gf*Gf - elt< A1 | 2^n, 0 >;
Df:=2^(-1)*Df;

DDf:=[];
V:=VectorSpace(GF(2),2*n);
for v in V do
j:=(&+[Integers()!v[i]*E[i]:i in [1..2*n]]);
if Coefficient(Df,j) eq 1 then Append(~DDf,G!(&+[Integers()!v[i]*E[i]:i in [1..2*n]])); end if;
end for;
DDf:=&+[A!g : g in DDf];
J:=ideal<A|DDf>;

DeltaRank:=Dimension(J);
return DeltaRank; end function;