How can I do matrix multiplication based on MinkowskiEngine?

[xing-yuu]

I have a matrix A with shape 1,1,3,5, and another matrix B with shape [1,1,5,4].
Now, using function MinkowskiEngine.MinkowskiOps.to_sparse, I want to convert them into sparse matrices and multiply the two matrices to obtain a matrix with shape [1,1,3,4].

How can I do？