"Source: Text/Commut/RngInvar.text";
"Line: 1627";
"Date: Thu Sep 25 14:47:46 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Commut/RngInvar.text, line: 1627
// Example: H120E14 ()
print "Example: H120E14";
ei := GetEchoInput();
SetEchoInput(true);
K:=GF(3);
F4:=MatrixGroup<4,K |
  [-1,0,0,0, 1,1,0,0, 0,0,1,0, 0,0,0,1], 
  [1,1,0,0, 0,-1,0,0, 0,1,1,0, 0,0,0,1],
  [1,0,0,0, 0,1,-1,0, 0,0,-1,0, 0,0,1,1],
  [1,0,0,0, 0,1,0,0, 0,0,1,1, 0,0,0,-1] >;
R := InvariantRing(F4);
f2 := InvariantsOfDegree(R, 2)[1];
f4 := SteenrodOperation(f2, 1);
f10 := SteenrodOperation(f4, 3);
f4;
f10;
f4 in R;
assert $1;
f10 in R;
assert $1;
SetEchoInput(ei);
