Inner derivation through the universal bimodule derivation
= Inner derivation through the universal bimodule derivation
Under the universal isomorphism, the inner derivation $d_m(r)=rm-mr$ corresponds to
$$
\theta_m\left(\sum_ir_i\otimes s_i\right)=\sum_ir_ims_i.
$$
Thus inner derivations correspond exactly to bimodule maps on $\Omega_R^{\mathrm{nc}}$ that extend across the inclusion $\Omega_R^{\mathrm{nc}}\subseteq R\otimes_kR$.