Classification of commutation relation for multi-radial SLE

Abstract: Locally commuting multiple radial Schramm-Loewner evolutions ($\mathrm{SLE}_κ$) are encoded by partition functions satisfying the radial Belavin-Polyakov-Zamolodchikov (BPZ) equations and a conformal Ward identity with spectral parameters $λ,ν\in\mathbb{R}$. For $κ>0$ and $λ\in\mathbb{R}$, we show that the solution space of the radial BPZ system has dimension $2^n$, where $n$ is the number of variables. We then determine all admissible Ward parameters $ν$ and the exact dimensions of the subspaces selected by the conformal Ward identity, covering both generic and degenerate cases. The classification reveals a parity difference: nonzero rotation-invariant solutions exist for every $λ$ when $n$ is even, but only at finitely many exceptional values when $n$ is odd. When $0<κ\leq4$, $λ>0$ for odd $n$ or $λ>-3/2$ for even $n$, we construct a basis of positive solutions using multiple SLE, providing global realizations of the locally commuting SLEs. At $κ=4$, we identify a family of explicit solutions as partition functions for level lines of a Gaussian free field with suitable boundary data and interior singularities.