POLYNOMIAL INVARIANTS OF FOUR-DIMENSIONAL ORTHOGONAL GROUPS
Huah Chu · Communications in Algebra · 2001
Let Q be a nondegenerate quadratic form over the finite field F q and O n (F q ) be the associated orthogonal group. Let O n (F q ) act linearly on the polynomial ring F q [x 1, …, x n ]. We find the invariant subring of O 4(F q ) with explicit generators.