2. For pairwise interactions, there's a single coupling, Kuramoto's: sin(−θj+θk). But for higher-order ones, there's many more, e.g. sin(−2θj+θk+θl) and sin(−θj+2θk− θl) for 3- bodies, and their dynamics differ!
So, which couplings should we choose?
And what physical models do they represent?
