I have a question about reciprocal lattice of graphene. When we see LEED pattern, we can know that reciprocal lattice of graphene is honeycomb. But how can we know theorically that it is honeycomb? Hexagonal lattice or other bravais lattice has just lattice vectors which don`t contain baises. So it is just straight forward. In case of graphene which is not a bravais lattice, how can we get a reciprocal lattice?