Faster class group computations using norm relations
Norm relations
For H ≤ G, define the norm element
NH =
X
h∈H
h ∈ Z[G].
Wada, Bauch–Bernstein–de Valence–Lange–van Vredendaal,
Biasse–van Vredendaal : G = C2 × C2 = hσ, τi.
2 = Nhσi + Nhσi − σNhστi.
Parry, Lesavourey–Plantard–Susilo : G = C3 × C3 = hu, vi.
3 = Nhui + Nhvi + Nhuvi − (u + uv)Nhu2vi.