Let f:Rd→R be a Lipschitz function. If B is a
bounded self-adjoint operator and if {Ak}k=1d are commuting bounded
self-adjoint operators such that [Ak,B]∈L1(H), then
∥[f(A1,⋯,Ad),B]∥1,∞≤c(d)∥∇(f)∥∞1≤k≤dmax∥[Ak,B]∥1, where c(d) is
a constant independent of f, M and A,B and
∥⋅∥1,∞ denotes the weak L1-norm. If {Xk}k=1d
(respectively, {Yk}k=1d) are commuting bounded self-adjoint operators
such that Xk−Yk∈L1(H), then
∥f(X1,⋯,Xd)−f(Y1,⋯,Yd)∥1,∞≤c(d)∥∇(f)∥∞1≤k≤dmax∥Xk−Yk∥1.